[PATCH RFC tip/core/rcu 0/30] RCU commits queued for 2.6.36/7

[PATCH RFC tip/core/rcu 0/30] RCU commits queued for 2.6.36/7

[Paul E. McKenney]

Hello!

This patchset shows the patches queued for 2.6.36/7.  These are not
yet ready to move upstream due to dependencies on commits moving up other
trees.  The patches are as follows:

1-19.	These are the remaining patches implementing Arnd's sparse-checking
	work.  #1 needs to go up the networking tree, but
	will cause regressions until f5155b33277 ("rcu: add an
	rcu_dereference_index_check()") reaches mainline.  #2 depends
	on #1, and many of the later patches (#3-#30) depend on #2.
	Many of #3-#19 will go up non-tip trees.
20.	Update Documentation/RCU to remove the now-deprecated rcu_head
	initialization macros.
21.	Fix long-standing DocBook example showing long-dead three-argument
	variant of call_rcu().
22.	Make the CPU stall warning timeout configurable at build time
	with new RCU_CPU_STALL_TIMEOUT config parameter.
23.	Remove the now-deprecated rcu_head initialization macros.
	This depends on a couple of patches removing their use that
	are making their way up other maintainer trees.
24.	Document the new debug assists from Arnd, Mathieu, and myself.
25.	Add random preemption to rcutorture testing of preemptible
	RCU, courtesy of Lai Jiangshan.
26.	Remove TREE_RCU's ->rda[] array in favor of the new __percpu
	facility, also courtesy of Lai Jiangshan.
27.	Fixlet to #26 for RCU tracing.
28.	Rename __do_rcu_dereference_check() to rcu_lockdep_assert(),
	given that Tetsuo Handa has found outside-of-RCU use for this
	function.
29.	Add a boot parameter to suppress RCU CPU stall warnings.
30.	Update kerneldoc or rcu_read_lock(), call_rcu(), and
	synchronize_rcu().

For a testing-only git-tree version of this patchset, see:

git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu.git rcu/testing

By "testing-only" I mean that any of the commits in the rcu/testing branch
might be folded, spindled, or otherwise mutilated at any time.  ;-)

							Thanx, Paul

 Documentation/DocBook/kernel-locking.tmpl   |    6 
 b/Documentation/DocBook/kernel-locking.tmpl |    8 
 b/Documentation/RCU/checklist.txt           |   23 +
 b/arch/x86/include/asm/kvm_host.h           |    2 
 b/drivers/input/evdev.c                     |    2 
 b/drivers/net/bnx2.h                        |    2 
 b/drivers/net/bnx2x.h                       |    2 
 b/drivers/net/cnic.h                        |    2 
 b/drivers/net/macvtap.c                     |    2 
 b/drivers/vhost/net.c                       |   15 -
 b/drivers/vhost/vhost.c                     |   29 +-
 b/drivers/vhost/vhost.h                     |   11 
 b/include/linux/cgroup.h                    |    4 
 b/include/linux/compiler.h                  |    4 
 b/include/linux/cred.h                      |    2 
 b/include/linux/fdtable.h                   |    6 
 b/include/linux/fs.h                        |    2 
 b/include/linux/genhd.h                     |    6 
 b/include/linux/idr.h                       |    4 
 b/include/linux/if_macvlan.h                |    2 
 b/include/linux/igmp.h                      |    4 
 b/include/linux/init_task.h                 |    4 
 b/include/linux/input.h                     |    2 
 b/include/linux/iocontext.h                 |    2 
 b/include/linux/key.h                       |    3 
 b/include/linux/kvm_host.h                  |    2 
 b/include/linux/mm_types.h                  |    2 
 b/include/linux/netdevice.h                 |   12 
 b/include/linux/nfs_fs.h                    |    2 
 b/include/linux/notifier.h                  |   10 
 b/include/linux/perf_event.h                |    6 
 b/include/linux/radix-tree.h                |    4 
 b/include/linux/rculist.h                   |   53 ++--
 b/include/linux/rculist_nulls.h             |   16 -
 b/include/linux/rcupdate.h                  |  352 ++++++++++++++++------------
 b/include/linux/sched.h                     |    2 
 b/include/linux/srcu.h                      |   27 +-
 b/include/linux/sunrpc/auth_gss.h           |    4 
 b/include/net/cls_cgroup.h                  |    3 
 b/include/net/dst.h                         |    2 
 b/include/net/fib_rules.h                   |    2 
 b/include/net/garp.h                        |    2 
 b/include/net/inet_sock.h                   |    2 
 b/include/net/ip6_tunnel.h                  |    2 
 b/include/net/ipip.h                        |    6 
 b/include/net/net_namespace.h               |    2 
 b/include/net/netfilter/nf_conntrack.h      |    2 
 b/include/net/netns/xfrm.h                  |    2 
 b/include/net/sock.h                        |    4 
 b/kernel/cgroup.c                           |    2 
 b/kernel/pid.c                              |    2 
 b/kernel/rcupdate.c                         |    6 
 b/kernel/rcutorture.c                       |    6 
 b/kernel/rcutree.c                          |   42 +--
 b/kernel/rcutree.h                          |    5 
 b/kernel/rcutree_plugin.h                   |    4 
 b/kernel/rcutree_trace.c                    |    2 
 b/kernel/sched.c                            |    2 
 b/lib/Kconfig.debug                         |   13 +
 b/lib/radix-tree.c                          |    2 
 b/net/802/stp.c                             |    4 
 b/net/ipv4/ip_gre.c                         |    2 
 b/net/ipv4/ipip.c                           |   10 
 b/net/ipv4/netfilter/nf_nat_core.c          |    2 
 b/net/ipv4/protocol.c                       |    2 
 b/net/ipv4/route.c                          |    2 
 b/net/ipv4/tcp.c                            |    4 
 b/net/ipv6/ip6_tunnel.c                     |    6 
 b/net/ipv6/protocol.c                       |    2 
 b/net/ipv6/sit.c                            |   10 
 b/net/mac80211/ieee80211_i.h                |   15 -
 b/net/mac80211/sta_info.h                   |    4 
 b/net/netfilter/core.c                      |    2 
 b/net/netfilter/nf_conntrack_ecache.c       |    4 
 b/net/netfilter/nf_conntrack_extend.c       |    2 
 b/net/netfilter/nf_conntrack_proto.c        |    4 
 b/net/netfilter/nf_log.c                    |    2 
 b/net/netfilter/nf_queue.c                  |    2 
 b/net/netlabel/netlabel_domainhash.c        |    4 
 b/net/netlabel/netlabel_unlabeled.c         |    4 
 b/net/netlink/af_netlink.c                  |    2 
 b/net/phonet/af_phonet.c                    |    2 
 b/net/phonet/pn_dev.c                       |    2 
 b/net/socket.c                              |    2 
 include/linux/kvm_host.h                    |    4 
 include/linux/rcupdate.h                    |   36 +-
 include/linux/sched.h                       |    6 
 kernel/rcutree.c                            |   11 
 kernel/rcutree.h                            |    2 
 kernel/rcutree_plugin.h                     |    8 
 lib/Kconfig.debug                           |   11 
 91 files changed, 563 insertions(+), 366 deletions(-)

[PATCH RFC tip/core/rcu 01/30] net: convert to rcu_dereference_index_check()

[Paul E. McKenney]

The task_cls_classid() function applies rcu_dereference() to integers,
which does not work with the shiny new sparse-based checking in
rcu_dereference().  This commit therefore moves to the new RCU API
rcu_dereference_index_check().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/net/cls_cgroup.h |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/include/net/cls_cgroup.h b/include/net/cls_cgroup.h
index 726cc35..dd1fdb8 100644
--- a/include/net/cls_cgroup.h
+++ b/include/net/cls_cgroup.h
@@ -45,7 +45,8 @@ static inline u32 task_cls_classid(struct task_struct *p)
 		return 0;
 
 	rcu_read_lock();
-	id = rcu_dereference(net_cls_subsys_id);
+	id = rcu_dereference_index_check(net_cls_subsys_id,
+					 rcu_read_lock_held());
 	if (id >= 0)
 		classid = container_of(task_subsys_state(p, id),
 				       struct cgroup_cls_state, css)->classid;
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 02/30] rcu: define __rcu address space modifier for sparse

[Paul E. McKenney]

This commit provides definitions for the __rcu annotation defined earlier.
This annotation permits sparse to check for correct use of RCU-protected
pointers.  If a pointer that is annotated with __rcu is accessed
directly (as opposed to via rcu_dereference(), rcu_assign_pointer(),
or one of their variants), sparse can be made to complain.  To enable
such complaints, use the new default-disabled CONFIG_SPARSE_RCU_POINTER
kernel configuration option.  Please note that these sparse complaints are
intended to be a debugging aid, -not- a code-style-enforcement mechanism.

There are special rcu_dereference_protected() and rcu_access_pointer()
accessors for use when RCU read-side protection is not required, for
example, when no other CPU has access to the data structure in question
or while the current CPU hold the update-side lock.

This patch also updates a number of docbook comments that were showing
their age.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Christopher Li <sparse@chrisli.org>
Cc: Josh Triplett <josh@joshtriplett.org>
---
 include/linux/compiler.h |    4 +
 include/linux/rcupdate.h |  352 ++++++++++++++++++++++++++++------------------
 include/linux/srcu.h     |   27 +++-
 kernel/rcupdate.c        |    6 +-
 lib/Kconfig.debug        |   13 ++
 5 files changed, 257 insertions(+), 145 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index c1a62c5..320d6c9 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -16,7 +16,11 @@
 # define __release(x)	__context__(x,-1)
 # define __cond_lock(x,c)	((c) ? ({ __acquire(x); 1; }) : 0)
 # define __percpu	__attribute__((noderef, address_space(3)))
+#ifdef CONFIG_SPARSE_RCU_POINTER
+# define __rcu		__attribute__((noderef, address_space(4)))
+#else
 # define __rcu
+#endif
 extern void __chk_user_ptr(const volatile void __user *);
 extern void __chk_io_ptr(const volatile void __iomem *);
 #else
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 9fbc54a..b973dea 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -41,6 +41,7 @@
 #include <linux/lockdep.h>
 #include <linux/completion.h>
 #include <linux/debugobjects.h>
+#include <linux/compiler.h>
 
 #ifdef CONFIG_RCU_TORTURE_TEST
 extern int rcutorture_runnable; /* for sysctl */
@@ -120,14 +121,15 @@ extern struct lockdep_map rcu_sched_lock_map;
 extern int debug_lockdep_rcu_enabled(void);
 
 /**
- * rcu_read_lock_held - might we be in RCU read-side critical section?
+ * rcu_read_lock_held() - might we be in RCU read-side critical section?
  *
  * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an RCU
  * read-side critical section.  In absence of CONFIG_DEBUG_LOCK_ALLOC,
  * this assumes we are in an RCU read-side critical section unless it can
- * prove otherwise.
+ * prove otherwise.  This is useful for debug checks in functions that
+ * require that they be called within an RCU read-side critical section.
  *
- * Check debug_lockdep_rcu_enabled() to prevent false positives during boot
+ * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
  * and while lockdep is disabled.
  */
 static inline int rcu_read_lock_held(void)
@@ -144,14 +146,16 @@ static inline int rcu_read_lock_held(void)
 extern int rcu_read_lock_bh_held(void);
 
 /**
- * rcu_read_lock_sched_held - might we be in RCU-sched read-side critical section?
+ * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section?
  *
  * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an
  * RCU-sched read-side critical section.  In absence of
  * CONFIG_DEBUG_LOCK_ALLOC, this assumes we are in an RCU-sched read-side
  * critical section unless it can prove otherwise.  Note that disabling
  * of preemption (including disabling irqs) counts as an RCU-sched
- * read-side critical section.
+ * read-side critical section.  This is useful for debug checks in functions
+ * that required that they be called within an RCU-sched read-side
+ * critical section.
  *
  * Check debug_lockdep_rcu_enabled() to prevent false positives during boot
  * and while lockdep is disabled.
@@ -220,41 +224,155 @@ extern int rcu_my_thread_group_empty(void);
 		}							\
 	} while (0)
 
+#else /* #ifdef CONFIG_PROVE_RCU */
+
+#define __do_rcu_dereference_check(c) do { } while (0)
+
+#endif /* #else #ifdef CONFIG_PROVE_RCU */
+
+/*
+ * Helper functions for rcu_dereference_check(), rcu_dereference_protected()
+ * and rcu_assign_pointer().  Some of these could be folded into their
+ * callers, but they are left separate in order to ease introduction of
+ * multiple flavors of pointers to match the multiple flavors of RCU
+ * (e.g., __rcu_bh, * __rcu_sched, and __srcu), should this make sense in
+ * the future.
+ */
+#define __rcu_access_pointer(p, space) \
+	({ \
+		typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
+		(void) (((typeof (*p) space *)p) == p); \
+		((typeof(*p) __force __kernel *)(_________p1)); \
+	})
+#define __rcu_dereference_check(p, c, space) \
+	({ \
+		typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
+		__do_rcu_dereference_check(c); \
+		(void) (((typeof (*p) space *)p) == p); \
+		smp_read_barrier_depends(); \
+		((typeof(*p) __force __kernel *)(_________p1)); \
+	})
+#define __rcu_dereference_protected(p, c, space) \
+	({ \
+		__do_rcu_dereference_check(c); \
+		(void) (((typeof (*p) space *)p) == p); \
+		((typeof(*p) __force __kernel *)(p)); \
+	})
+
+#define __rcu_dereference_index_check(p, c) \
+	({ \
+		typeof(p) _________p1 = ACCESS_ONCE(p); \
+		__do_rcu_dereference_check(c); \
+		smp_read_barrier_depends(); \
+		(_________p1); \
+	})
+#define __rcu_assign_pointer(p, v, space) \
+	({ \
+		if (!__builtin_constant_p(v) || \
+		    ((v) != NULL)) \
+			smp_wmb(); \
+		(p) = (typeof(*v) __force space *)(v); \
+	})
+
+
+/**
+ * rcu_access_pointer() - fetch RCU pointer with no dereferencing
+ * @p: The pointer to read
+ *
+ * Return the value of the specified RCU-protected pointer, but omit the
+ * smp_read_barrier_depends() and keep the ACCESS_ONCE().  This is useful
+ * when the value of this pointer is accessed, but the pointer is not
+ * dereferenced, for example, when testing an RCU-protected pointer against
+ * NULL.  Although rcu_access_pointer() may also be used in cases where
+ * update-side locks prevent the value of the pointer from changing, you
+ * should instead use rcu_dereference_protected() for this use case.
+ */
+#define rcu_access_pointer(p) __rcu_access_pointer((p), __rcu)
+
 /**
- * rcu_dereference_check - rcu_dereference with debug checking
+ * rcu_dereference_check() - rcu_dereference with debug checking
  * @p: The pointer to read, prior to dereferencing
  * @c: The conditions under which the dereference will take place
  *
  * Do an rcu_dereference(), but check that the conditions under which the
- * dereference will take place are correct.  Typically the conditions indicate
- * the various locking conditions that should be held at that point.  The check
- * should return true if the conditions are satisfied.
+ * dereference will take place are correct.  Typically the conditions
+ * indicate the various locking conditions that should be held at that
+ * point.  The check should return true if the conditions are satisfied.
+ * An implicit check for being in an RCU read-side critical section
+ * (rcu_read_lock()) is included.
  *
  * For example:
  *
- *	bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
- *					      lockdep_is_held(&foo->lock));
+ *	bar = rcu_dereference_check(foo->bar, lockdep_is_held(&foo->lock));
  *
  * could be used to indicate to lockdep that foo->bar may only be dereferenced
- * if either the RCU read lock is held, or that the lock required to replace
+ * if either rcu_read_lock() is held, or that the lock required to replace
  * the bar struct at foo->bar is held.
  *
  * Note that the list of conditions may also include indications of when a lock
  * need not be held, for example during initialisation or destruction of the
  * target struct:
  *
- *	bar = rcu_dereference_check(foo->bar, rcu_read_lock_held() ||
- *					      lockdep_is_held(&foo->lock) ||
+ *	bar = rcu_dereference_check(foo->bar, lockdep_is_held(&foo->lock) ||
  *					      atomic_read(&foo->usage) == 0);
+ *
+ * Inserts memory barriers on architectures that require them
+ * (currently only the Alpha), prevents the compiler from refetching
+ * (and from merging fetches), and, more importantly, documents exactly
+ * which pointers are protected by RCU and checks that the pointer is
+ * annotated as __rcu.
  */
 #define rcu_dereference_check(p, c) \
-	({ \
-		__do_rcu_dereference_check(c); \
-		rcu_dereference_raw(p); \
-	})
+	__rcu_dereference_check((p), rcu_read_lock_held() || (c), __rcu)
+
+/**
+ * rcu_dereference_bh_check() - rcu_dereference_bh with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * This is the RCU-bh counterpart to rcu_dereference_check().
+ */
+#define rcu_dereference_bh_check(p, c) \
+	__rcu_dereference_check((p), rcu_read_lock_bh_held() || (c), __rcu)
 
 /**
- * rcu_dereference_protected - fetch RCU pointer when updates prevented
+ * rcu_dereference_sched_check() - rcu_dereference_sched with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * This is the RCU-sched counterpart to rcu_dereference_check().
+ */
+#define rcu_dereference_sched_check(p, c) \
+	__rcu_dereference_check((p), rcu_read_lock_sched_held() || (c), \
+				__rcu)
+
+#define rcu_dereference_raw(p) rcu_dereference_check(p, 1) /*@@@ needed? @@@*/
+
+/**
+ * rcu_dereference_index_check() - rcu_dereference for indices with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * Similar to rcu_dereference_check(), but omits the sparse checking.
+ * This allows rcu_dereference_index_check() to be used on integers,
+ * which can then be used as array indices.  Attempting to use
+ * rcu_dereference_check() on an integer will give compiler warnings
+ * because the sparse address-space mechanism relies on dereferencing
+ * the RCU-protected pointer.  Dereferencing integers is not something
+ * that even gcc will put up with.
+ *
+ * Note that this function does not implicitly check for RCU read-side
+ * critical sections.  If this function gains lots of uses, it might
+ * make sense to provide versions for each flavor of RCU, but it does
+ * not make sense as of early 2010.
+ */
+#define rcu_dereference_index_check(p, c) \
+	__rcu_dereference_index_check((p), (c))
+
+/**
+ * rcu_dereference_protected() - fetch RCU pointer when updates prevented
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
  *
  * Return the value of the specified RCU-protected pointer, but omit
  * both the smp_read_barrier_depends() and the ACCESS_ONCE().  This
@@ -263,35 +381,61 @@ extern int rcu_my_thread_group_empty(void);
  * prevent the compiler from repeating this reference or combining it
  * with other references, so it should not be used without protection
  * of appropriate locks.
+ *
+ * This function is only for update-side use.  Using this function
+ * when protected only by rcu_read_lock() will result in infrequent
+ * but very ugly failures.
  */
 #define rcu_dereference_protected(p, c) \
-	({ \
-		__do_rcu_dereference_check(c); \
-		(p); \
-	})
+	__rcu_dereference_protected((p), (c), __rcu)
 
-#else /* #ifdef CONFIG_PROVE_RCU */
+/**
+ * rcu_dereference_bh_protected() - fetch RCU-bh pointer when updates prevented
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * This is the RCU-bh counterpart to rcu_dereference_protected().
+ */
+#define rcu_dereference_bh_protected(p, c) \
+	__rcu_dereference_protected((p), (c), __rcu)
 
-#define rcu_dereference_check(p, c)	rcu_dereference_raw(p)
-#define rcu_dereference_protected(p, c) (p)
+/**
+ * rcu_dereference_sched_protected() - fetch RCU-sched pointer when updates prevented
+ * @p: The pointer to read, prior to dereferencing
+ * @c: The conditions under which the dereference will take place
+ *
+ * This is the RCU-sched counterpart to rcu_dereference_protected().
+ */
+#define rcu_dereference_sched_protected(p, c) \
+	__rcu_dereference_protected((p), (c), __rcu)
 
-#endif /* #else #ifdef CONFIG_PROVE_RCU */
 
 /**
- * rcu_access_pointer - fetch RCU pointer with no dereferencing
+ * rcu_dereference() - fetch RCU-protected pointer for dereferencing
+ * @p: The pointer to read, prior to dereferencing
  *
- * Return the value of the specified RCU-protected pointer, but omit the
- * smp_read_barrier_depends() and keep the ACCESS_ONCE().  This is useful
- * when the value of this pointer is accessed, but the pointer is not
- * dereferenced, for example, when testing an RCU-protected pointer against
- * NULL.  This may also be used in cases where update-side locks prevent
- * the value of the pointer from changing, but rcu_dereference_protected()
- * is a lighter-weight primitive for this use case.
+ * This is a simple wrapper around rcu_dereference_check().
  */
-#define rcu_access_pointer(p)	ACCESS_ONCE(p)
+#define rcu_dereference(p) rcu_dereference_check(p, 0)
 
 /**
- * rcu_read_lock - mark the beginning of an RCU read-side critical section.
+ * rcu_dereference_bh() - fetch an RCU-bh-protected pointer for dereferencing
+ * @p: The pointer to read, prior to dereferencing
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference_bh(p) rcu_dereference_bh_check(p, 0)
+
+/**
+ * rcu_dereference_sched() - fetch RCU-sched-protected pointer for dereferencing
+ * @p: The pointer to read, prior to dereferencing
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define rcu_dereference_sched(p) rcu_dereference_sched_check(p, 0)
+
+/**
+ * rcu_read_lock() - mark the beginning of an RCU read-side critical section
  *
  * When synchronize_rcu() is invoked on one CPU while other CPUs
  * are within RCU read-side critical sections, then the
@@ -337,7 +481,7 @@ static inline void rcu_read_lock(void)
  */
 
 /**
- * rcu_read_unlock - marks the end of an RCU read-side critical section.
+ * rcu_read_unlock() - marks the end of an RCU read-side critical section.
  *
  * See rcu_read_lock() for more information.
  */
@@ -349,15 +493,16 @@ static inline void rcu_read_unlock(void)
 }
 
 /**
- * rcu_read_lock_bh - mark the beginning of a softirq-only RCU critical section
+ * rcu_read_lock_bh() - mark the beginning of an RCU-bh critical section
  *
  * This is equivalent of rcu_read_lock(), but to be used when updates
- * are being done using call_rcu_bh(). Since call_rcu_bh() callbacks
- * consider completion of a softirq handler to be a quiescent state,
- * a process in RCU read-side critical section must be protected by
- * disabling softirqs. Read-side critical sections in interrupt context
- * can use just rcu_read_lock().
- *
+ * are being done using call_rcu_bh() or synchronize_rcu_bh(). Since
+ * both call_rcu_bh() and synchronize_rcu_bh() consider completion of a
+ * softirq handler to be a quiescent state, a process in RCU read-side
+ * critical section must be protected by disabling softirqs. Read-side
+ * critical sections in interrupt context can use just rcu_read_lock(),
+ * though this should at least be commented to avoid confusing people
+ * reading the code.
  */
 static inline void rcu_read_lock_bh(void)
 {
@@ -379,13 +524,12 @@ static inline void rcu_read_unlock_bh(void)
 }
 
 /**
- * rcu_read_lock_sched - mark the beginning of a RCU-classic critical section
+ * rcu_read_lock_sched() - mark the beginning of a RCU-sched critical section
  *
- * Should be used with either
- * - synchronize_sched()
- * or
- * - call_rcu_sched() and rcu_barrier_sched()
- * on the write-side to insure proper synchronization.
+ * This is equivalent of rcu_read_lock(), but to be used when updates
+ * are being done using call_rcu_sched() or synchronize_rcu_sched().
+ * Read-side critical sections can also be introduced by anything that
+ * disables preemption, including local_irq_disable() and friends.
  */
 static inline void rcu_read_lock_sched(void)
 {
@@ -420,54 +564,14 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
 	preempt_enable_notrace();
 }
 
-
 /**
- * rcu_dereference_raw - fetch an RCU-protected pointer
+ * rcu_assign_pointer() - assign to RCU-protected pointer
+ * @p: pointer to assign to
+ * @v: value to assign (publish)
  *
- * The caller must be within some flavor of RCU read-side critical
- * section, or must be otherwise preventing the pointer from changing,
- * for example, by holding an appropriate lock.  This pointer may later
- * be safely dereferenced.  It is the caller's responsibility to have
- * done the right thing, as this primitive does no checking of any kind.
- *
- * Inserts memory barriers on architectures that require them
- * (currently only the Alpha), and, more importantly, documents
- * exactly which pointers are protected by RCU.
- */
-#define rcu_dereference_raw(p)	({ \
-				typeof(p) _________p1 = ACCESS_ONCE(p); \
-				smp_read_barrier_depends(); \
-				(_________p1); \
-				})
-
-/**
- * rcu_dereference - fetch an RCU-protected pointer, checking for RCU
- *
- * Makes rcu_dereference_check() do the dirty work.
- */
-#define rcu_dereference(p) \
-	rcu_dereference_check(p, rcu_read_lock_held())
-
-/**
- * rcu_dereference_bh - fetch an RCU-protected pointer, checking for RCU-bh
- *
- * Makes rcu_dereference_check() do the dirty work.
- */
-#define rcu_dereference_bh(p) \
-		rcu_dereference_check(p, rcu_read_lock_bh_held())
-
-/**
- * rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched
- *
- * Makes rcu_dereference_check() do the dirty work.
- */
-#define rcu_dereference_sched(p) \
-		rcu_dereference_check(p, rcu_read_lock_sched_held())
-
-/**
- * rcu_assign_pointer - assign (publicize) a pointer to a newly
- * initialized structure that will be dereferenced by RCU read-side
- * critical sections.  Returns the value assigned.
+ * Assigns the specified value to the specified RCU-protected
+ * pointer, ensuring that any concurrent RCU readers will see
+ * any prior initialization.  Returns the value assigned.
  *
  * Inserts memory barriers on architectures that require them
  * (pretty much all of them other than x86), and also prevents
@@ -476,14 +580,17 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
  * call documents which pointers will be dereferenced by RCU read-side
  * code.
  */
-
 #define rcu_assign_pointer(p, v) \
-	({ \
-		if (!__builtin_constant_p(v) || \
-		    ((v) != NULL)) \
-			smp_wmb(); \
-		(p) = (v); \
-	})
+	__rcu_assign_pointer((p), (v), __rcu)
+
+/**
+ * RCU_INIT_POINTER() - initialize an RCU protected pointer
+ *
+ * Initialize an RCU-protected pointer in such a way to avoid RCU-lockdep
+ * splats.
+ */
+#define RCU_INIT_POINTER(p, v) \
+		p = (typeof(*v) __force __rcu *)(v)
 
 /* Infrastructure to implement the synchronize_() primitives. */
 
@@ -495,7 +602,7 @@ struct rcu_synchronize {
 extern void wakeme_after_rcu(struct rcu_head  *head);
 
 /**
- * call_rcu - Queue an RCU callback for invocation after a grace period.
+ * call_rcu() - Queue an RCU callback for invocation after a grace period.
  * @head: structure to be used for queueing the RCU updates.
  * @func: actual update function to be invoked after the grace period
  *
@@ -509,7 +616,7 @@ extern void call_rcu(struct rcu_head *head,
 			      void (*func)(struct rcu_head *head));
 
 /**
- * call_rcu_bh - Queue an RCU for invocation after a quicker grace period.
+ * call_rcu_bh() - Queue an RCU for invocation after a quicker grace period.
  * @head: structure to be used for queueing the RCU updates.
  * @func: actual update function to be invoked after the grace period
  *
@@ -566,37 +673,4 @@ static inline void debug_rcu_head_unqueue(struct rcu_head *head)
 }
 #endif	/* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 
-#ifndef CONFIG_PROVE_RCU
-#define __do_rcu_dereference_check(c) do { } while (0)
-#endif /* #ifdef CONFIG_PROVE_RCU */
-
-#define __rcu_dereference_index_check(p, c) \
-	({ \
-		typeof(p) _________p1 = ACCESS_ONCE(p); \
-		__do_rcu_dereference_check(c); \
-		smp_read_barrier_depends(); \
-		(_________p1); \
-	})
-
-/**
- * rcu_dereference_index_check() - rcu_dereference for indices with debug checking
- * @p: The pointer to read, prior to dereferencing
- * @c: The conditions under which the dereference will take place
- *
- * Similar to rcu_dereference_check(), but omits the sparse checking.
- * This allows rcu_dereference_index_check() to be used on integers,
- * which can then be used as array indices.  Attempting to use
- * rcu_dereference_check() on an integer will give compiler warnings
- * because the sparse address-space mechanism relies on dereferencing
- * the RCU-protected pointer.  Dereferencing integers is not something
- * that even gcc will put up with.
- *
- * Note that this function does not implicitly check for RCU read-side
- * critical sections.  If this function gains lots of uses, it might
- * make sense to provide versions for each flavor of RCU, but it does
- * not make sense as of early 2010.
- */
-#define rcu_dereference_index_check(p, c) \
-	__rcu_dereference_index_check((p), (c))
-
 #endif /* __LINUX_RCUPDATE_H */
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 4d5d2f5..6f456a7 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -108,12 +108,31 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp)
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
 /**
- * srcu_dereference - fetch SRCU-protected pointer with checking
+ * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
+ * @p: the pointer to fetch and protect for later dereferencing
+ * @sp: pointer to the srcu_struct, which is used to check that we
+ *	really are in an SRCU read-side critical section.
+ * @c: condition to check for update-side use
  *
- * Makes rcu_dereference_check() do the dirty work.
+ * If PROVE_RCU is enabled, invoking this outside of an RCU read-side
+ * critical section will result in an RCU-lockdep splat, unless @c evaluates
+ * to 1.  The @c argument will normally be a logical expression containing
+ * lockdep_is_held() calls.
  */
-#define srcu_dereference(p, sp) \
-		rcu_dereference_check(p, srcu_read_lock_held(sp))
+#define srcu_dereference_check(p, sp, c) \
+	__rcu_dereference_check((p), srcu_read_lock_held(sp) || (c), __rcu)
+
+/**
+ * srcu_dereference - fetch SRCU-protected pointer for later dereferencing
+ * @p: the pointer to fetch and protect for later dereferencing
+ * @sp: pointer to the srcu_struct, which is used to check that we
+ *	really are in an SRCU read-side critical section.
+ *
+ * Makes rcu_dereference_check() do the dirty work.  If PROVE_RCU
+ * is enabled, invoking this outside of an RCU read-side critical
+ * section will result in an RCU-lockdep splat.
+ */
+#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
 
 /**
  * srcu_read_lock - register a new reader for an SRCU-protected structure.
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 4d16983..6c79e85 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -73,12 +73,14 @@ int debug_lockdep_rcu_enabled(void)
 EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
 
 /**
- * rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
+ * rcu_read_lock_bh_held() - might we be in RCU-bh read-side critical section?
  *
  * Check for bottom half being disabled, which covers both the
  * CONFIG_PROVE_RCU and not cases.  Note that if someone uses
  * rcu_read_lock_bh(), but then later enables BH, lockdep (if enabled)
- * will show the situation.
+ * will show the situation.  This is useful for debug checks in functions
+ * that require that they be called within an RCU read-side critical
+ * section.
  *
  * Check debug_lockdep_rcu_enabled() to prevent false positives during boot.
  */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 142faa2..a8a272a 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -528,6 +528,19 @@ config PROVE_RCU_REPEATEDLY
 	 disabling, allowing multiple RCU-lockdep warnings to be printed
 	 on a single reboot.
 
+config SPARSE_RCU_POINTER
+	bool "RCU debugging: sparse-based checks for pointer usage"
+	default n
+	help
+	 This feature enables the __rcu sparse annotation for
+	 RCU-protected pointers.  This annotation will cause sparse
+	 to flag any non-RCU used of annotated pointers.  This can be
+	 helpful when debugging RCU usage.  Please note that this feature
+	 is not intended to enforce code cleanliness; it is instead merely
+	 a debugging aid.
+
+	 Say Y to make sparse flag questionable use of RCU-protected pointers
+
 	 Say N if you are unsure.
 
 config LOCKDEP
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 03/30] rculist: avoid __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

This avoids warnings from missing __rcu annotations
in the rculist implementation, making it possible to
use the same lists in both RCU and non-RCU cases.

We can add rculist annotations later, together with
lockdep support for rculist, which is missing as well,
but that may involve changing all the users.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
---
 include/linux/rculist.h       |   53 ++++++++++++++++++++++++++--------------
 include/linux/rculist_nulls.h |   16 ++++++++----
 kernel/pid.c                  |    2 +-
 3 files changed, 46 insertions(+), 25 deletions(-)

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 4ec3b38..c10b105 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -10,6 +10,12 @@
 #include <linux/rcupdate.h>
 
 /*
+ * return the ->next pointer of a list_head in an rcu safe
+ * way, we must not access it directly
+ */
+#define list_next_rcu(list)	(*((struct list_head __rcu **)(&(list)->next)))
+
+/*
  * Insert a new entry between two known consecutive entries.
  *
  * This is only for internal list manipulation where we know
@@ -20,7 +26,7 @@ static inline void __list_add_rcu(struct list_head *new,
 {
 	new->next = next;
 	new->prev = prev;
-	rcu_assign_pointer(prev->next, new);
+	rcu_assign_pointer(list_next_rcu(prev), new);
 	next->prev = new;
 }
 
@@ -138,7 +144,7 @@ static inline void list_replace_rcu(struct list_head *old,
 {
 	new->next = old->next;
 	new->prev = old->prev;
-	rcu_assign_pointer(new->prev->next, new);
+	rcu_assign_pointer(list_next_rcu(new->prev), new);
 	new->next->prev = new;
 	old->prev = LIST_POISON2;
 }
@@ -193,7 +199,7 @@ static inline void list_splice_init_rcu(struct list_head *list,
 	 */
 
 	last->next = at;
-	rcu_assign_pointer(head->next, first);
+	rcu_assign_pointer(list_next_rcu(head), first);
 	first->prev = head;
 	at->prev = last;
 }
@@ -208,7 +214,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock().
  */
 #define list_entry_rcu(ptr, type, member) \
-	container_of(rcu_dereference_raw(ptr), type, member)
+	({typeof (*ptr) __rcu *__ptr = (typeof (*ptr) __rcu __force *)ptr; \
+	 container_of((typeof(ptr))rcu_dereference_raw(__ptr), type, member); \
+	})
 
 /**
  * list_first_entry_rcu - get the first element from a list
@@ -225,9 +233,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
 	list_entry_rcu((ptr)->next, type, member)
 
 #define __list_for_each_rcu(pos, head) \
-	for (pos = rcu_dereference_raw((head)->next); \
+	for (pos = rcu_dereference_raw(list_next_rcu(head)); \
 		pos != (head); \
-		pos = rcu_dereference_raw(pos->next))
+		pos = rcu_dereference_raw(list_next_rcu((pos)))
 
 /**
  * list_for_each_entry_rcu	-	iterate over rcu list of given type
@@ -257,9 +265,9 @@ static inline void list_splice_init_rcu(struct list_head *list,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define list_for_each_continue_rcu(pos, head) \
-	for ((pos) = rcu_dereference_raw((pos)->next); \
+	for ((pos) = rcu_dereference_raw(list_next_rcu(pos)); \
 		prefetch((pos)->next), (pos) != (head); \
-		(pos) = rcu_dereference_raw((pos)->next))
+		(pos) = rcu_dereference_raw(list_next_rcu(pos)))
 
 /**
  * list_for_each_entry_continue_rcu - continue iteration over list of given type
@@ -314,12 +322,19 @@ static inline void hlist_replace_rcu(struct hlist_node *old,
 
 	new->next = next;
 	new->pprev = old->pprev;
-	rcu_assign_pointer(*new->pprev, new);
+	rcu_assign_pointer(*(struct hlist_node __rcu **)new->pprev, new);
 	if (next)
 		new->next->pprev = &new->next;
 	old->pprev = LIST_POISON2;
 }
 
+/*
+ * return the first or the next element in an RCU protected hlist
+ */
+#define hlist_first_rcu(head)	(*((struct hlist_node __rcu **)(&(head)->first)))
+#define hlist_next_rcu(node)	(*((struct hlist_node __rcu **)(&(node)->next)))
+#define hlist_pprev_rcu(node)	(*((struct hlist_node __rcu **)((node)->pprev)))
+
 /**
  * hlist_add_head_rcu
  * @n: the element to add to the hash list.
@@ -346,7 +361,7 @@ static inline void hlist_add_head_rcu(struct hlist_node *n,
 
 	n->next = first;
 	n->pprev = &h->first;
-	rcu_assign_pointer(h->first, n);
+	rcu_assign_pointer(hlist_first_rcu(h), n);
 	if (first)
 		first->pprev = &n->next;
 }
@@ -374,7 +389,7 @@ static inline void hlist_add_before_rcu(struct hlist_node *n,
 {
 	n->pprev = next->pprev;
 	n->next = next;
-	rcu_assign_pointer(*(n->pprev), n);
+	rcu_assign_pointer(hlist_pprev_rcu(n), n);
 	next->pprev = &n->next;
 }
 
@@ -401,15 +416,15 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
 {
 	n->next = prev->next;
 	n->pprev = &prev->next;
-	rcu_assign_pointer(prev->next, n);
+	rcu_assign_pointer(hlist_next_rcu(prev), n);
 	if (n->next)
 		n->next->pprev = &n->next;
 }
 
-#define __hlist_for_each_rcu(pos, head)			\
-	for (pos = rcu_dereference((head)->first);	\
-	     pos && ({ prefetch(pos->next); 1; });	\
-	     pos = rcu_dereference(pos->next))
+#define __hlist_for_each_rcu(pos, head)				\
+	for (pos = rcu_dereference(hlist_first_rcu(head));	\
+	     pos && ({ prefetch(pos->next); 1; });		\
+	     pos = rcu_dereference(hlist_next_rcu(pos)))
 
 /**
  * hlist_for_each_entry_rcu - iterate over rcu list of given type
@@ -422,11 +437,11 @@ static inline void hlist_add_after_rcu(struct hlist_node *prev,
  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
  * as long as the traversal is guarded by rcu_read_lock().
  */
-#define hlist_for_each_entry_rcu(tpos, pos, head, member)		 \
-	for (pos = rcu_dereference_raw((head)->first);			 \
+#define hlist_for_each_entry_rcu(tpos, pos, head, member)		\
+	for (pos = rcu_dereference_raw(hlist_first_rcu(head));		\
 		pos && ({ prefetch(pos->next); 1; }) &&			 \
 		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1; }); \
-		pos = rcu_dereference_raw(pos->next))
+		pos = rcu_dereference_raw(hlist_next_rcu(pos)))
 
 /**
  * hlist_for_each_entry_rcu_bh - iterate over rcu list of given type
diff --git a/include/linux/rculist_nulls.h b/include/linux/rculist_nulls.h
index b70ffe5..2ae1371 100644
--- a/include/linux/rculist_nulls.h
+++ b/include/linux/rculist_nulls.h
@@ -37,6 +37,12 @@ static inline void hlist_nulls_del_init_rcu(struct hlist_nulls_node *n)
 	}
 }
 
+#define hlist_nulls_first_rcu(head) \
+	(*((struct hlist_nulls_node __rcu __force **)&(head)->first))
+
+#define hlist_nulls_next_rcu(node) \
+	(*((struct hlist_nulls_node __rcu __force **)&(node)->next))
+
 /**
  * hlist_nulls_del_rcu - deletes entry from hash list without re-initialization
  * @n: the element to delete from the hash list.
@@ -88,7 +94,7 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
 
 	n->next = first;
 	n->pprev = &h->first;
-	rcu_assign_pointer(h->first, n);
+	rcu_assign_pointer(hlist_nulls_first_rcu(h), n);
 	if (!is_a_nulls(first))
 		first->pprev = &n->next;
 }
@@ -100,11 +106,11 @@ static inline void hlist_nulls_add_head_rcu(struct hlist_nulls_node *n,
  * @member:	the name of the hlist_nulls_node within the struct.
  *
  */
-#define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member) \
-	for (pos = rcu_dereference_raw((head)->first);			 \
-		(!is_a_nulls(pos)) &&			\
+#define hlist_nulls_for_each_entry_rcu(tpos, pos, head, member)			\
+	for (pos = rcu_dereference_raw(hlist_nulls_first_rcu(head));		\
+		(!is_a_nulls(pos)) &&						\
 		({ tpos = hlist_nulls_entry(pos, typeof(*tpos), member); 1; }); \
-		pos = rcu_dereference_raw(pos->next))
+		pos = rcu_dereference_raw(hlist_nulls_next_rcu(pos)))
 
 #endif
 #endif
diff --git a/kernel/pid.c b/kernel/pid.c
index e9fd8c1..28e8ce4 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -367,7 +367,7 @@ struct task_struct *pid_task(struct pid *pid, enum pid_type type)
 	struct task_struct *result = NULL;
 	if (pid) {
 		struct hlist_node *first;
-		first = rcu_dereference_check(pid->tasks[type].first,
+		first = rcu_dereference_check(hlist_first_rcu(&pid->tasks[type]),
 					      rcu_read_lock_held() ||
 					      lockdep_tasklist_lock_is_held());
 		if (first)
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 04/30] cgroups: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
---
 include/linux/cgroup.h |    4 ++--
 include/linux/sched.h  |    2 +-
 kernel/cgroup.c        |    2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index e3d00fd..1e7ce60 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -75,7 +75,7 @@ struct cgroup_subsys_state {
 
 	unsigned long flags;
 	/* ID for this css, if possible */
-	struct css_id *id;
+	struct css_id __rcu *id;
 };
 
 /* bits in struct cgroup_subsys_state flags field */
@@ -205,7 +205,7 @@ struct cgroup {
 	struct list_head children;	/* my children */
 
 	struct cgroup *parent;		/* my parent */
-	struct dentry *dentry;	  	/* cgroup fs entry, RCU protected */
+	struct dentry __rcu *dentry;	/* cgroup fs entry, RCU protected */
 
 	/* Private pointers for each registered subsystem */
 	struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f118809..97fc7ee 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1427,7 +1427,7 @@ struct task_struct {
 #endif
 #ifdef CONFIG_CGROUPS
 	/* Control Group info protected by css_set_lock */
-	struct css_set *cgroups;
+	struct css_set __rcu *cgroups;
 	/* cg_list protected by css_set_lock and tsk->alloc_lock */
 	struct list_head cg_list;
 #endif
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3ac6f5b..30c459b 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -138,7 +138,7 @@ struct css_id {
 	 * is called after synchronize_rcu(). But for safe use, css_is_removed()
 	 * css_tryget() should be used for avoiding race.
 	 */
-	struct cgroup_subsys_state *css;
+	struct cgroup_subsys_state __rcu *css;
 	/*
 	 * ID of this css.
 	 */
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 05/30] credentials: rcu annotation

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
---
 include/linux/sched.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 97fc7ee..9a2d9a0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1297,9 +1297,9 @@ struct task_struct {
 	struct list_head cpu_timers[3];
 
 /* process credentials */
-	const struct cred *real_cred;	/* objective and real subjective task
+	const struct cred __rcu *real_cred; /* objective and real subjective task
 					 * credentials (COW) */
-	const struct cred *cred;	/* effective (overridable) subjective task
+	const struct cred __rcu *cred;	/* effective (overridable) subjective task
 					 * credentials (COW) */
 	struct mutex cred_guard_mutex;	/* guard against foreign influences on
 					 * credential calculations
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 06/30] keys: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: David Howells <dhowells@redhat.com>
---
 include/linux/cred.h |    2 +-
 include/linux/key.h  |    3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/cred.h b/include/linux/cred.h
index 75c0fa8..94d2301 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -84,7 +84,7 @@ struct thread_group_cred {
 	atomic_t	usage;
 	pid_t		tgid;			/* thread group process ID */
 	spinlock_t	lock;
-	struct key	*session_keyring;	/* keyring inherited over fork */
+	struct key __rcu *session_keyring;	/* keyring inherited over fork */
 	struct key	*process_keyring;	/* keyring private to this process */
 	struct rcu_head	rcu;			/* RCU deletion hook */
 };
diff --git a/include/linux/key.h b/include/linux/key.h
index cd50dfa..3db0adc 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -178,8 +178,9 @@ struct key {
 	 */
 	union {
 		unsigned long		value;
+		void __rcu		*rcudata;
 		void			*data;
-		struct keyring_list	*subscriptions;
+		struct keyring_list __rcu *subscriptions;
 	} payload;
 };
 
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 07/30] nfs: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
---
 include/linux/nfs_fs.h          |    2 +-
 include/linux/sunrpc/auth_gss.h |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 77c2ae5..a619070 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -178,7 +178,7 @@ struct nfs_inode {
 	struct nfs4_cached_acl	*nfs4_acl;
         /* NFSv4 state */
 	struct list_head	open_states;
-	struct nfs_delegation	*delegation;
+	struct nfs_delegation __rcu *delegation;
 	fmode_t			 delegation_state;
 	struct rw_semaphore	rwsem;
 #endif /* CONFIG_NFS_V4*/
diff --git a/include/linux/sunrpc/auth_gss.h b/include/linux/sunrpc/auth_gss.h
index 671538d..8eee9db 100644
--- a/include/linux/sunrpc/auth_gss.h
+++ b/include/linux/sunrpc/auth_gss.h
@@ -69,7 +69,7 @@ struct gss_cl_ctx {
 	enum rpc_gss_proc	gc_proc;
 	u32			gc_seq;
 	spinlock_t		gc_seq_lock;
-	struct gss_ctx		*gc_gss_ctx;
+	struct gss_ctx __rcu	*gc_gss_ctx;
 	struct xdr_netobj	gc_wire_ctx;
 	u32			gc_win;
 	unsigned long		gc_expiry;
@@ -80,7 +80,7 @@ struct gss_upcall_msg;
 struct gss_cred {
 	struct rpc_cred		gc_base;
 	enum rpc_gss_svc	gc_service;
-	struct gss_cl_ctx	*gc_ctx;
+	struct gss_cl_ctx __rcu	*gc_ctx;
 	struct gss_upcall_msg	*gc_upcall;
 	unsigned long		gc_upcall_timestamp;
 	unsigned char		gc_machine_cred : 1;
-- 
1.7.0.6

Re: [PATCH RFC tip/core/rcu 07/30] nfs: __rcu annotations

[Trond Myklebust]

On Wed, 2010-07-14 at 13:09 -0700, Paul E. McKenney wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Trond Myklebust <Trond.Myklebust@netapp.com>

Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>

> ---
>  include/linux/nfs_fs.h          |    2 +-
>  include/linux/sunrpc/auth_gss.h |    4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 77c2ae5..a619070 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -178,7 +178,7 @@ struct nfs_inode {
>  	struct nfs4_cached_acl	*nfs4_acl;
>          /* NFSv4 state */
>  	struct list_head	open_states;
> -	struct nfs_delegation	*delegation;
> +	struct nfs_delegation __rcu *delegation;
>  	fmode_t			 delegation_state;
>  	struct rw_semaphore	rwsem;
>  #endif /* CONFIG_NFS_V4*/
> diff --git a/include/linux/sunrpc/auth_gss.h b/include/linux/sunrpc/auth_gss.h
> index 671538d..8eee9db 100644
> --- a/include/linux/sunrpc/auth_gss.h
> +++ b/include/linux/sunrpc/auth_gss.h
> @@ -69,7 +69,7 @@ struct gss_cl_ctx {
>  	enum rpc_gss_proc	gc_proc;
>  	u32			gc_seq;
>  	spinlock_t		gc_seq_lock;
> -	struct gss_ctx		*gc_gss_ctx;
> +	struct gss_ctx __rcu	*gc_gss_ctx;
>  	struct xdr_netobj	gc_wire_ctx;
>  	u32			gc_win;
>  	unsigned long		gc_expiry;
> @@ -80,7 +80,7 @@ struct gss_upcall_msg;
>  struct gss_cred {
>  	struct rpc_cred		gc_base;
>  	enum rpc_gss_svc	gc_service;
> -	struct gss_cl_ctx	*gc_ctx;
> +	struct gss_cl_ctx __rcu	*gc_ctx;
>  	struct gss_upcall_msg	*gc_upcall;
>  	unsigned long		gc_upcall_timestamp;
>  	unsigned char		gc_machine_cred : 1;

[PATCH RFC tip/core/rcu 08/30] net: __rcu annotations for drivers

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
---
 drivers/net/bnx2.h         |    2 +-
 drivers/net/bnx2x.h        |    2 +-
 drivers/net/cnic.h         |    2 +-
 drivers/net/macvtap.c      |    2 +-
 include/linux/if_macvlan.h |    2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/bnx2.h b/drivers/net/bnx2.h
index ddaa3fc..ec0db55 100644
--- a/drivers/net/bnx2.h
+++ b/drivers/net/bnx2.h
@@ -6749,7 +6749,7 @@ struct bnx2 {
 	u32		tx_wake_thresh;
 
 #ifdef BCM_CNIC
-	struct cnic_ops		*cnic_ops;
+	struct cnic_ops	__rcu	*cnic_ops;
 	void			*cnic_data;
 #endif
 
diff --git a/drivers/net/bnx2x.h b/drivers/net/bnx2x.h
index 8bd2368..b83ebd4 100644
--- a/drivers/net/bnx2x.h
+++ b/drivers/net/bnx2x.h
@@ -1036,7 +1036,7 @@ struct bnx2x {
 	dma_addr_t		timers_mapping;
 	void			*qm;
 	dma_addr_t		qm_mapping;
-	struct cnic_ops		*cnic_ops;
+	struct cnic_ops __rcu	*cnic_ops;
 	void			*cnic_data;
 	u32			cnic_tag;
 	struct cnic_eth_dev	cnic_eth_dev;
diff --git a/drivers/net/cnic.h b/drivers/net/cnic.h
index 08b1235..038da24 100644
--- a/drivers/net/cnic.h
+++ b/drivers/net/cnic.h
@@ -177,7 +177,7 @@ struct cnic_local {
 #define ULP_F_INIT	0
 #define ULP_F_START	1
 #define ULP_F_CALL_PENDING	2
-	struct cnic_ulp_ops *ulp_ops[MAX_CNIC_ULP_TYPE];
+	struct cnic_ulp_ops __rcu *ulp_ops[MAX_CNIC_ULP_TYPE];
 
 	unsigned long cnic_local_flags;
 #define	CNIC_LCL_FL_KWQ_INIT		0x0
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index a8a94e2..aa0e0c8 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -39,7 +39,7 @@ struct macvtap_queue {
 	struct socket sock;
 	struct socket_wq wq;
 	int vnet_hdr_sz;
-	struct macvlan_dev *vlan;
+	struct macvlan_dev __rcu *vlan;
 	struct file *file;
 	unsigned int flags;
 };
diff --git a/include/linux/if_macvlan.h b/include/linux/if_macvlan.h
index 9ea047a..7d768bc 100644
--- a/include/linux/if_macvlan.h
+++ b/include/linux/if_macvlan.h
@@ -47,7 +47,7 @@ struct macvlan_dev {
 	enum macvlan_mode	mode;
 	int (*receive)(struct sk_buff *skb);
 	int (*forward)(struct net_device *dev, struct sk_buff *skb);
-	struct macvtap_queue	*tap;
+	struct macvtap_queue __rcu *tap;
 };
 
 static inline void macvlan_count_rx(const struct macvlan_dev *vlan,
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 09/30] perf_event: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 include/linux/perf_event.h |    6 +++---
 include/linux/sched.h      |    2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 5d0266d..b30ee92 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -645,7 +645,7 @@ struct perf_event {
 	struct hlist_node		hlist_entry;
 	int				nr_siblings;
 	int				group_flags;
-	struct perf_event		*group_leader;
+	struct perf_event __rcu		*group_leader;
 	const struct pmu		*pmu;
 
 	enum perf_event_active_state	state;
@@ -709,7 +709,7 @@ struct perf_event {
 	atomic_t			mmap_count;
 	int				mmap_locked;
 	struct user_struct		*mmap_user;
-	struct perf_mmap_data		*data;
+	struct perf_mmap_data __rcu	*data;
 
 	/* poll related */
 	wait_queue_head_t		waitq;
@@ -777,7 +777,7 @@ struct perf_event_context {
 	 * These fields let us detect when two contexts have both
 	 * been cloned (inherited) from a common ancestor.
 	 */
-	struct perf_event_context	*parent_ctx;
+	struct perf_event_context __rcu *parent_ctx;
 	u64				parent_gen;
 	u64				generation;
 	int				pin_count;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9a2d9a0..26b85fe 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1440,7 +1440,7 @@ struct task_struct {
 	struct futex_pi_state *pi_state_cache;
 #endif
 #ifdef CONFIG_PERF_EVENTS
-	struct perf_event_context *perf_event_ctxp;
+	struct perf_event_context __rcu *perf_event_ctxp;
 	struct mutex perf_event_mutex;
 	struct list_head perf_event_list;
 #endif
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 10/30] notifiers: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
---
 include/linux/notifier.h |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index 540703b..ebf7210 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -49,28 +49,28 @@
 
 struct notifier_block {
 	int (*notifier_call)(struct notifier_block *, unsigned long, void *);
-	struct notifier_block *next;
+	struct notifier_block __rcu *next;
 	int priority;
 };
 
 struct atomic_notifier_head {
 	spinlock_t lock;
-	struct notifier_block *head;
+	struct notifier_block __rcu *head;
 };
 
 struct blocking_notifier_head {
 	struct rw_semaphore rwsem;
-	struct notifier_block *head;
+	struct notifier_block __rcu *head;
 };
 
 struct raw_notifier_head {
-	struct notifier_block *head;
+	struct notifier_block __rcu *head;
 };
 
 struct srcu_notifier_head {
 	struct mutex mutex;
 	struct srcu_struct srcu;
-	struct notifier_block *head;
+	struct notifier_block __rcu *head;
 };
 
 #define ATOMIC_INIT_NOTIFIER_HEAD(name) do {	\
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 11/30] radix-tree: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Nick Piggin <npiggin@suse.de>
---
 include/linux/radix-tree.h |    4 +++-
 lib/radix-tree.c           |    2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 55ca73c..d801044 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -47,6 +47,8 @@ static inline void *radix_tree_indirect_to_ptr(void *ptr)
 {
 	return (void *)((unsigned long)ptr & ~RADIX_TREE_INDIRECT_PTR);
 }
+#define radix_tree_indirect_to_ptr(ptr) \
+	radix_tree_indirect_to_ptr((void __force *)(ptr))
 
 static inline int radix_tree_is_indirect_ptr(void *ptr)
 {
@@ -61,7 +63,7 @@ static inline int radix_tree_is_indirect_ptr(void *ptr)
 struct radix_tree_root {
 	unsigned int		height;
 	gfp_t			gfp_mask;
-	struct radix_tree_node	*rnode;
+	struct radix_tree_node	__rcu *rnode;
 };
 
 #define RADIX_TREE_INIT(mask)	{					\
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 05da38b..8bd7ae3 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -49,7 +49,7 @@ struct radix_tree_node {
 	unsigned int	height;		/* Height from the bottom */
 	unsigned int	count;
 	struct rcu_head	rcu_head;
-	void		*slots[RADIX_TREE_MAP_SIZE];
+	void __rcu	*slots[RADIX_TREE_MAP_SIZE];
 	unsigned long	tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
 };
 
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 12/30] idr: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
---
 include/linux/idr.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index e968db7..cdb715e 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -50,14 +50,14 @@
 
 struct idr_layer {
 	unsigned long		 bitmap; /* A zero bit means "space here" */
-	struct idr_layer	*ary[1<<IDR_BITS];
+	struct idr_layer __rcu	*ary[1<<IDR_BITS];
 	int			 count;	 /* When zero, we can release it */
 	int			 layer;	 /* distance from leaf */
 	struct rcu_head		 rcu_head;
 };
 
 struct idr {
-	struct idr_layer *top;
+	struct idr_layer __rcu *top;
 	struct idr_layer *id_free;
 	int		  layers; /* only valid without concurrent changes */
 	int		  id_free_cnt;
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 13/30] input: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
---
 drivers/input/evdev.c |    2 +-
 include/linux/input.h |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index 2ee6c7a..73b1208 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -28,7 +28,7 @@ struct evdev {
 	int minor;
 	struct input_handle handle;
 	wait_queue_head_t wait;
-	struct evdev_client *grab;
+	struct evdev_client __rcu *grab;
 	struct list_head client_list;
 	spinlock_t client_lock; /* protects client_list */
 	struct mutex mutex;
diff --git a/include/linux/input.h b/include/linux/input.h
index 6fcc910..4d2d239 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -1174,7 +1174,7 @@ struct input_dev {
 	int (*flush)(struct input_dev *dev, struct file *file);
 	int (*event)(struct input_dev *dev, unsigned int type, unsigned int code, int value);
 
-	struct input_handle *grab;
+	struct input_handle __rcu *grab;
 
 	spinlock_t event_lock;
 	struct mutex mutex;
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 14/30] net/netfilter: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@relay.de.ibm.com>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
---
 include/net/netfilter/nf_conntrack.h |    2 +-
 net/ipv4/netfilter/nf_nat_core.c     |    2 +-
 net/netfilter/core.c                 |    2 +-
 net/netfilter/nf_conntrack_ecache.c  |    4 ++--
 net/netfilter/nf_conntrack_extend.c  |    2 +-
 net/netfilter/nf_conntrack_proto.c   |    4 ++--
 net/netfilter/nf_log.c               |    2 +-
 net/netfilter/nf_queue.c             |    2 +-
 8 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index bde095f..92229d1 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -75,7 +75,7 @@ struct nf_conntrack_helper;
 /* nf_conn feature for connections that have a helper */
 struct nf_conn_help {
 	/* Helper. if any */
-	struct nf_conntrack_helper *helper;
+	struct nf_conntrack_helper __rcu *helper;
 
 	union nf_conntrack_help help;
 
diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index 4f8bddb..1263f2a 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -38,7 +38,7 @@ static DEFINE_SPINLOCK(nf_nat_lock);
 static struct nf_conntrack_l3proto *l3proto __read_mostly;
 
 #define MAX_IP_NAT_PROTO 256
-static const struct nf_nat_protocol *nf_nat_protos[MAX_IP_NAT_PROTO]
+static const struct nf_nat_protocol __rcu *nf_nat_protos[MAX_IP_NAT_PROTO]
 						__read_mostly;
 
 static inline const struct nf_nat_protocol *
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
index 78b505d..fdaec7d 100644
--- a/net/netfilter/core.c
+++ b/net/netfilter/core.c
@@ -27,7 +27,7 @@
 
 static DEFINE_MUTEX(afinfo_mutex);
 
-const struct nf_afinfo *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
+const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO] __read_mostly;
 EXPORT_SYMBOL(nf_afinfo);
 
 int nf_register_afinfo(const struct nf_afinfo *afinfo)
diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c
index cdcc764..5702de3 100644
--- a/net/netfilter/nf_conntrack_ecache.c
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -26,10 +26,10 @@
 
 static DEFINE_MUTEX(nf_ct_ecache_mutex);
 
-struct nf_ct_event_notifier *nf_conntrack_event_cb __read_mostly;
+struct nf_ct_event_notifier __rcu *nf_conntrack_event_cb __read_mostly;
 EXPORT_SYMBOL_GPL(nf_conntrack_event_cb);
 
-struct nf_exp_event_notifier *nf_expect_event_cb __read_mostly;
+struct nf_exp_event_notifier __rcu *nf_expect_event_cb __read_mostly;
 EXPORT_SYMBOL_GPL(nf_expect_event_cb);
 
 /* deliver cached events and clear cache entry - must be called with locally
diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c
index fdc8fb4..9a0f75f 100644
--- a/net/netfilter/nf_conntrack_extend.c
+++ b/net/netfilter/nf_conntrack_extend.c
@@ -16,7 +16,7 @@
 #include <linux/skbuff.h>
 #include <net/netfilter/nf_conntrack_extend.h>
 
-static struct nf_ct_ext_type *nf_ct_ext_types[NF_CT_EXT_NUM];
+static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM];
 static DEFINE_MUTEX(nf_ct_ext_type_mutex);
 
 void __nf_ct_ext_destroy(struct nf_conn *ct)
diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
index 5886ba1..ed6d929 100644
--- a/net/netfilter/nf_conntrack_proto.c
+++ b/net/netfilter/nf_conntrack_proto.c
@@ -28,8 +28,8 @@
 #include <net/netfilter/nf_conntrack_l4proto.h>
 #include <net/netfilter/nf_conntrack_core.h>
 
-static struct nf_conntrack_l4proto **nf_ct_protos[PF_MAX] __read_mostly;
-struct nf_conntrack_l3proto *nf_ct_l3protos[AF_MAX] __read_mostly;
+static struct nf_conntrack_l4proto __rcu **nf_ct_protos[PF_MAX] __read_mostly;
+struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[AF_MAX] __read_mostly;
 EXPORT_SYMBOL_GPL(nf_ct_l3protos);
 
 static DEFINE_MUTEX(nf_ct_proto_mutex);
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 7df37fd..b07393e 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -16,7 +16,7 @@
 #define NF_LOG_PREFIXLEN		128
 #define NFLOGGER_NAME_LEN		64
 
-static const struct nf_logger *nf_loggers[NFPROTO_NUMPROTO] __read_mostly;
+static const struct nf_logger __rcu *nf_loggers[NFPROTO_NUMPROTO] __read_mostly;
 static struct list_head nf_loggers_l[NFPROTO_NUMPROTO] __read_mostly;
 static DEFINE_MUTEX(nf_log_mutex);
 
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index 78b3cf9..74aebed 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -18,7 +18,7 @@
  * long term mutex.  The handler must provide an an outfn() to accept packets
  * for queueing and must reinject all packets it receives, no matter what.
  */
-static const struct nf_queue_handler *queue_handler[NFPROTO_NUMPROTO] __read_mostly;
+static const struct nf_queue_handler __rcu *queue_handler[NFPROTO_NUMPROTO] __read_mostly;
 
 static DEFINE_MUTEX(queue_handler_mutex);
 
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 15/30] kvm: add __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
---
 include/linux/kvm_host.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 7cb116a..b34b1b4 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -203,7 +203,7 @@ struct kvm {
 
 	struct mutex irq_lock;
 #ifdef CONFIG_HAVE_KVM_IRQCHIP
-	struct kvm_irq_routing_table *irq_routing;
+	struct kvm_irq_routing_table __rcu *irq_routing;
 	struct hlist_head mask_notifier_list;
 	struct hlist_head irq_ack_notifier_list;
 #endif
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 16/30] kernel: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@arndb.de>

This adds annotations for RCU operations in core kernel components

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/fdtable.h   |    6 +++---
 include/linux/fs.h        |    2 +-
 include/linux/genhd.h     |    6 +++---
 include/linux/init_task.h |    4 ++--
 include/linux/iocontext.h |    2 +-
 include/linux/mm_types.h  |    2 +-
 6 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 551671e..3e4c4f4 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -31,7 +31,7 @@ struct embedded_fd_set {
 
 struct fdtable {
 	unsigned int max_fds;
-	struct file ** fd;      /* current fd array */
+	struct file __rcu **fd;      /* current fd array */
 	fd_set *close_on_exec;
 	fd_set *open_fds;
 	struct rcu_head rcu;
@@ -46,7 +46,7 @@ struct files_struct {
    * read mostly part
    */
 	atomic_t count;
-	struct fdtable *fdt;
+	struct fdtable __rcu *fdt;
 	struct fdtable fdtab;
   /*
    * written part on a separate cache line in SMP
@@ -55,7 +55,7 @@ struct files_struct {
 	int next_fd;
 	struct embedded_fd_set close_on_exec_init;
 	struct embedded_fd_set open_fds_init;
-	struct file * fd_array[NR_OPEN_DEFAULT];
+	struct file __rcu * fd_array[NR_OPEN_DEFAULT];
 };
 
 #define rcu_dereference_check_fdtable(files, fdtfd) \
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 471e1ff..65ed90f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1381,7 +1381,7 @@ struct super_block {
 	 * Saved mount options for lazy filesystems using
 	 * generic_show_options()
 	 */
-	char *s_options;
+	char __rcu *s_options;
 };
 
 extern struct timespec current_fs_time(struct super_block *sb);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 5f2f4c4..af3f06b 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -129,8 +129,8 @@ struct blk_scsi_cmd_filter {
 struct disk_part_tbl {
 	struct rcu_head rcu_head;
 	int len;
-	struct hd_struct *last_lookup;
-	struct hd_struct *part[];
+	struct hd_struct __rcu *last_lookup;
+	struct hd_struct __rcu *part[];
 };
 
 struct gendisk {
@@ -149,7 +149,7 @@ struct gendisk {
 	 * non-critical accesses use RCU.  Always access through
 	 * helpers.
 	 */
-	struct disk_part_tbl *part_tbl;
+	struct disk_part_tbl __rcu *part_tbl;
 	struct hd_struct part0;
 
 	const struct block_device_operations *fops;
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 1f43fa5..6460fc6 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -137,8 +137,8 @@ extern struct cred init_cred;
 	.children	= LIST_HEAD_INIT(tsk.children),			\
 	.sibling	= LIST_HEAD_INIT(tsk.sibling),			\
 	.group_leader	= &tsk,						\
-	.real_cred	= &init_cred,					\
-	.cred		= &init_cred,					\
+	RCU_INIT_POINTER(.real_cred, &init_cred),			\
+	RCU_INIT_POINTER(.cred, &init_cred),				\
 	.cred_guard_mutex =						\
 		 __MUTEX_INITIALIZER(tsk.cred_guard_mutex),		\
 	.comm		= "swapper",					\
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index 64d5291..3e70b21 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -53,7 +53,7 @@ struct io_context {
 
 	struct radix_tree_root radix_root;
 	struct hlist_head cic_list;
-	void *ioc_data;
+	void __rcu *ioc_data;
 };
 
 static inline struct io_context *ioc_task_link(struct io_context *ioc)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b8bb9a6..05537a5 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -299,7 +299,7 @@ struct mm_struct {
 	 * new_owner->mm == mm
 	 * new_owner->alloc_lock is held
 	 */
-	struct task_struct *owner;
+	struct task_struct __rcu *owner;
 #endif
 
 #ifdef CONFIG_PROC_FS
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 17/30] net: __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@relay.de.ibm.com>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
---
 include/linux/igmp.h               |    4 ++--
 include/linux/netdevice.h          |   12 ++++++------
 include/net/dst.h                  |    2 +-
 include/net/fib_rules.h            |    2 +-
 include/net/garp.h                 |    2 +-
 include/net/inet_sock.h            |    2 +-
 include/net/ip6_tunnel.h           |    2 +-
 include/net/ipip.h                 |    6 +++---
 include/net/net_namespace.h        |    2 +-
 include/net/netns/xfrm.h           |    2 +-
 include/net/sock.h                 |    4 ++--
 kernel/sched.c                     |    2 +-
 net/802/stp.c                      |    4 ++--
 net/ipv4/ip_gre.c                  |    2 +-
 net/ipv4/ipip.c                    |   10 +++++-----
 net/ipv4/protocol.c                |    2 +-
 net/ipv4/route.c                   |    2 +-
 net/ipv4/tcp.c                     |    4 ++--
 net/ipv6/ip6_tunnel.c              |    6 +++---
 net/ipv6/protocol.c                |    2 +-
 net/ipv6/sit.c                     |   10 +++++-----
 net/mac80211/ieee80211_i.h         |   15 ++++++++-------
 net/mac80211/sta_info.h            |    4 ++--
 net/netlabel/netlabel_domainhash.c |    4 ++--
 net/netlabel/netlabel_unlabeled.c  |    4 ++--
 net/netlink/af_netlink.c           |    2 +-
 net/phonet/af_phonet.c             |    2 +-
 net/phonet/pn_dev.c                |    2 +-
 net/socket.c                       |    2 +-
 29 files changed, 60 insertions(+), 59 deletions(-)

diff --git a/include/linux/igmp.h b/include/linux/igmp.h
index 93fc244..39dd315 100644
--- a/include/linux/igmp.h
+++ b/include/linux/igmp.h
@@ -167,10 +167,10 @@ struct ip_sf_socklist {
  */
 
 struct ip_mc_socklist {
-	struct ip_mc_socklist	*next;
+	struct ip_mc_socklist __rcu *next;
 	struct ip_mreqn		multi;
 	unsigned int		sfmode;		/* MCAST_{INCLUDE,EXCLUDE} */
-	struct ip_sf_socklist	*sflist;
+	struct ip_sf_socklist __rcu *sflist;
 	struct rcu_head		rcu;
 };
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 40291f3..6bc5b2b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -924,10 +924,10 @@ struct net_device {
 #ifdef CONFIG_NET_DSA
 	void			*dsa_ptr;	/* dsa specific data */
 #endif
-	void 			*atalk_ptr;	/* AppleTalk link 	*/
-	void			*ip_ptr;	/* IPv4 specific data	*/
+	void			*atalk_ptr;	/* AppleTalk link	*/
+	void __rcu		*ip_ptr;	/* IPv4 specific data	*/
 	void                    *dn_ptr;        /* DECnet specific data */
-	void                    *ip6_ptr;       /* IPv6 specific data */
+	void __rcu              *ip6_ptr;       /* IPv6 specific data */
 	void			*ec_ptr;	/* Econet specific data	*/
 	void			*ax25_ptr;	/* AX.25 specific data */
 	struct wireless_dev	*ieee80211_ptr;	/* IEEE 802.11 specific data,
@@ -1025,11 +1025,11 @@ struct net_device {
 	void			*ml_priv;
 
 	/* bridge stuff */
-	struct net_bridge_port	*br_port;
+	void __rcu		*br_port;
 	/* macvlan */
-	struct macvlan_port	*macvlan_port;
+	struct macvlan_port __rcu *macvlan_port;
 	/* GARP */
-	struct garp_port	*garp_port;
+	struct garp_port __rcu	*garp_port;
 
 	/* class/net/name entry */
 	struct device		dev;
diff --git a/include/net/dst.h b/include/net/dst.h
index 81d1413..6cffcfa 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -94,7 +94,7 @@ struct dst_entry {
 	unsigned long		lastuse;
 	union {
 		struct dst_entry *next;
-		struct rtable    *rt_next;
+		struct rtable   __rcu *rt_next;
 		struct rt6_info   *rt6_next;
 		struct dn_route  *dn_next;
 	};
diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index e8923bc..a6b3482 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -20,7 +20,7 @@ struct fib_rule {
 	u32			table;
 	u8			action;
 	u32			target;
-	struct fib_rule *	ctarget;
+	struct fib_rule __rcu  *ctarget;
 	char			iifname[IFNAMSIZ];
 	char			oifname[IFNAMSIZ];
 	struct rcu_head		rcu;
diff --git a/include/net/garp.h b/include/net/garp.h
index 825f172..15b30ba 100644
--- a/include/net/garp.h
+++ b/include/net/garp.h
@@ -107,7 +107,7 @@ struct garp_applicant {
 };
 
 struct garp_port {
-	struct garp_applicant	*applicants[GARP_APPLICATION_MAX + 1];
+	struct garp_applicant __rcu *applicants[GARP_APPLICATION_MAX + 1];
 };
 
 extern int	garp_register_application(struct garp_application *app);
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 1653de5..ac764a3 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -140,7 +140,7 @@ struct inet_sock {
 				mc_all:1;
 	int			mc_index;
 	__be32			mc_addr;
-	struct ip_mc_socklist	*mc_list;
+	struct ip_mc_socklist __rcu *mc_list;
 	struct {
 		unsigned int		flags;
 		unsigned int		fragsize;
diff --git a/include/net/ip6_tunnel.h b/include/net/ip6_tunnel.h
index fbf9d1c..94fa2cc 100644
--- a/include/net/ip6_tunnel.h
+++ b/include/net/ip6_tunnel.h
@@ -13,7 +13,7 @@
 /* IPv6 tunnel */
 
 struct ip6_tnl {
-	struct ip6_tnl *next;	/* next tunnel in list */
+	struct ip6_tnl __rcu *next;	/* next tunnel in list */
 	struct net_device *dev;	/* virtual device associated with tunnel */
 	struct ip6_tnl_parm parms;	/* tunnel configuration parameters */
 	struct flowi fl;	/* flowi template for xmit */
diff --git a/include/net/ipip.h b/include/net/ipip.h
index 11e8513..ea186ab 100644
--- a/include/net/ipip.h
+++ b/include/net/ipip.h
@@ -16,7 +16,7 @@ struct ip_tunnel_6rd_parm {
 };
 
 struct ip_tunnel {
-	struct ip_tunnel	*next;
+	struct ip_tunnel __rcu	*next;
 	struct net_device	*dev;
 
 	int			err_count;	/* Number of arrived ICMP errors */
@@ -34,12 +34,12 @@ struct ip_tunnel {
 #ifdef CONFIG_IPV6_SIT_6RD
 	struct ip_tunnel_6rd_parm	ip6rd;
 #endif
-	struct ip_tunnel_prl_entry	*prl;		/* potential router list */
+	struct ip_tunnel_prl_entry __rcu *prl;		/* potential router list */
 	unsigned int			prl_count;	/* # of entries in PRL */
 };
 
 struct ip_tunnel_prl_entry {
-	struct ip_tunnel_prl_entry	*next;
+	struct ip_tunnel_prl_entry __rcu *next;
 	__be32				addr;
 	u16				flags;
 	struct rcu_head			rcu_head;
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index bd10a79..573d100 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -90,7 +90,7 @@ struct net {
 #ifdef CONFIG_WEXT_CORE
 	struct sk_buff_head	wext_nlevents;
 #endif
-	struct net_generic	*gen;
+	struct net_generic __rcu *gen;
 };
 
 
diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index 74f119a..9e0915d 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -48,7 +48,7 @@ struct netns_xfrm {
 	struct dst_ops		xfrm6_dst_ops;
 #endif
 
-	struct sock		*nlsk;
+	struct sock __rcu	*nlsk;
 	struct sock		*nlsk_stash;
 
 	u32			sysctl_aevent_etime;
diff --git a/include/net/sock.h b/include/net/sock.h
index 731150d..fea1b27 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -148,7 +148,7 @@ struct sock_common {
 	};
 	struct proto		*skc_prot;
 #ifdef CONFIG_NET_NS
-	struct net	 	*skc_net;
+	struct net __rcu	*skc_net;
 #endif
 };
 
@@ -298,7 +298,7 @@ struct sock {
 	struct ucred		sk_peercred;
 	long			sk_rcvtimeo;
 	long			sk_sndtimeo;
-	struct sk_filter      	*sk_filter;
+	struct sk_filter __rcu	*sk_filter;
 	void			*sk_protinfo;
 	struct timer_list	sk_timer;
 	ktime_t			sk_stamp;
diff --git a/kernel/sched.c b/kernel/sched.c
index cb816e3..8168128 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -496,7 +496,7 @@ struct rq {
 
 #ifdef CONFIG_SMP
 	struct root_domain *rd;
-	struct sched_domain *sd;
+	struct sched_domain __rcu *sd;
 
 	unsigned long cpu_power;
 
diff --git a/net/802/stp.c b/net/802/stp.c
index 53c8f77..978c30b 100644
--- a/net/802/stp.c
+++ b/net/802/stp.c
@@ -21,8 +21,8 @@
 #define GARP_ADDR_MAX	0x2F
 #define GARP_ADDR_RANGE	(GARP_ADDR_MAX - GARP_ADDR_MIN)
 
-static const struct stp_proto *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
-static const struct stp_proto *stp_proto __read_mostly;
+static const struct stp_proto __rcu *garp_protos[GARP_ADDR_RANGE + 1] __read_mostly;
+static const struct stp_proto __rcu *stp_proto __read_mostly;
 
 static struct llc_sap *sap __read_mostly;
 static unsigned int sap_registered;
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 32618e1..75f5e38 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -128,7 +128,7 @@ static int ipgre_tunnel_bind_dev(struct net_device *dev);
 
 static int ipgre_net_id __read_mostly;
 struct ipgre_net {
-	struct ip_tunnel *tunnels[4][HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels[4][HASH_SIZE];
 
 	struct net_device *fb_tunnel_dev;
 };
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 7fd6367..af0bb8b 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -122,11 +122,11 @@
 
 static int ipip_net_id __read_mostly;
 struct ipip_net {
-	struct ip_tunnel *tunnels_r_l[HASH_SIZE];
-	struct ip_tunnel *tunnels_r[HASH_SIZE];
-	struct ip_tunnel *tunnels_l[HASH_SIZE];
-	struct ip_tunnel *tunnels_wc[1];
-	struct ip_tunnel **tunnels[4];
+	struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_r[HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_l[HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_wc[1];
+	struct ip_tunnel __rcu **tunnels[4];
 
 	struct net_device *fb_tunnel_dev;
 };
diff --git a/net/ipv4/protocol.c b/net/ipv4/protocol.c
index 542f22f..ac2cf39 100644
--- a/net/ipv4/protocol.c
+++ b/net/ipv4/protocol.c
@@ -28,7 +28,7 @@
 #include <linux/spinlock.h>
 #include <net/protocol.h>
 
-const struct net_protocol *inet_protos[MAX_INET_PROTOS] ____cacheline_aligned_in_smp;
+const struct net_protocol __rcu *inet_protos[MAX_INET_PROTOS] ____cacheline_aligned_in_smp;
 static DEFINE_SPINLOCK(inet_proto_lock);
 
 /*
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 560acc6..e02e946 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -199,7 +199,7 @@ const __u8 ip_tos2prio[16] = {
  */
 
 struct rt_hash_bucket {
-	struct rtable	*chain;
+	struct rtable __rcu *chain;
 };
 
 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 6596b4f..3da762b 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3072,9 +3072,9 @@ static struct tcp_cookie_secret tcp_secret_one;
 static struct tcp_cookie_secret tcp_secret_two;
 
 /* Essentially a circular list, without dynamic allocation. */
-static struct tcp_cookie_secret *tcp_secret_generating;
+static struct tcp_cookie_secret __rcu *tcp_secret_generating;
 static struct tcp_cookie_secret *tcp_secret_primary;
-static struct tcp_cookie_secret *tcp_secret_retiring;
+static struct tcp_cookie_secret __rcu *tcp_secret_retiring;
 static struct tcp_cookie_secret *tcp_secret_secondary;
 
 static DEFINE_SPINLOCK(tcp_secret_locker);
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 8f39893..f72c1f8 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -83,9 +83,9 @@ struct ip6_tnl_net {
 	/* the IPv6 tunnel fallback device */
 	struct net_device *fb_tnl_dev;
 	/* lists for storing tunnels in use */
-	struct ip6_tnl *tnls_r_l[HASH_SIZE];
-	struct ip6_tnl *tnls_wc[1];
-	struct ip6_tnl **tnls[2];
+	struct ip6_tnl __rcu *tnls_r_l[HASH_SIZE];
+	struct ip6_tnl __rcu *tnls_wc[1];
+	struct ip6_tnl __rcu **tnls[2];
 };
 
 /*
diff --git a/net/ipv6/protocol.c b/net/ipv6/protocol.c
index 1fa3468..dee7e9d 100644
--- a/net/ipv6/protocol.c
+++ b/net/ipv6/protocol.c
@@ -25,7 +25,7 @@
 #include <linux/spinlock.h>
 #include <net/protocol.h>
 
-const struct inet6_protocol *inet6_protos[MAX_INET_PROTOS];
+const struct inet6_protocol __rcu *inet6_protos[MAX_INET_PROTOS];
 static DEFINE_SPINLOCK(inet6_proto_lock);
 
 
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index e51e650..9617720 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -68,11 +68,11 @@ static void ipip6_tunnel_setup(struct net_device *dev);
 
 static int sit_net_id __read_mostly;
 struct sit_net {
-	struct ip_tunnel *tunnels_r_l[HASH_SIZE];
-	struct ip_tunnel *tunnels_r[HASH_SIZE];
-	struct ip_tunnel *tunnels_l[HASH_SIZE];
-	struct ip_tunnel *tunnels_wc[1];
-	struct ip_tunnel **tunnels[4];
+	struct ip_tunnel __rcu *tunnels_r_l[HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_r[HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_l[HASH_SIZE];
+	struct ip_tunnel __rcu *tunnels_wc[1];
+	struct ip_tunnel __rcu **tunnels[4];
 
 	struct net_device *fb_tunnel_dev;
 };
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 1a9e2da..14318dc 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -192,7 +192,7 @@ struct beacon_data {
 };
 
 struct ieee80211_if_ap {
-	struct beacon_data *beacon;
+	struct beacon_data __rcu *beacon;
 
 	struct list_head vlans;
 
@@ -214,7 +214,7 @@ struct ieee80211_if_vlan {
 	struct list_head list;
 
 	/* used for all tx if the VLAN is configured to 4-addr mode */
-	struct sta_info *sta;
+	struct sta_info __rcu *sta;
 };
 
 struct mesh_stats {
@@ -407,7 +407,8 @@ struct ieee80211_if_ibss {
 
 	unsigned long ibss_join_req;
 	/* probe response/beacon for IBSS */
-	struct sk_buff *presp, *skb;
+	struct sk_buff __rcu *presp;
+	struct sk_buff *skb;
 
 	enum {
 		IEEE80211_IBSS_MLME_SEARCH,
@@ -511,9 +512,9 @@ struct ieee80211_sub_if_data {
 
 #define NUM_DEFAULT_KEYS 4
 #define NUM_DEFAULT_MGMT_KEYS 2
-	struct ieee80211_key *keys[NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS];
-	struct ieee80211_key *default_key;
-	struct ieee80211_key *default_mgmt_key;
+	struct ieee80211_key __rcu *keys[NUM_DEFAULT_KEYS + NUM_DEFAULT_MGMT_KEYS];
+	struct ieee80211_key __rcu *default_key;
+	struct ieee80211_key __rcu *default_mgmt_key;
 
 	u16 sequence_number;
 
@@ -716,7 +717,7 @@ struct ieee80211_local {
 	spinlock_t sta_lock;
 	unsigned long num_sta;
 	struct list_head sta_list, sta_pending_list;
-	struct sta_info *sta_hash[STA_HASH_SIZE];
+	struct sta_info __rcu *sta_hash[STA_HASH_SIZE];
 	struct timer_list sta_cleanup;
 	struct work_struct sta_finish_work;
 	int sta_generation;
diff --git a/net/mac80211/sta_info.h b/net/mac80211/sta_info.h
index df9d455..451e1dc 100644
--- a/net/mac80211/sta_info.h
+++ b/net/mac80211/sta_info.h
@@ -226,10 +226,10 @@ struct sta_ampdu_mlme {
 struct sta_info {
 	/* General information, mostly static */
 	struct list_head list;
-	struct sta_info *hnext;
+	struct sta_info __rcu *hnext;
 	struct ieee80211_local *local;
 	struct ieee80211_sub_if_data *sdata;
-	struct ieee80211_key *key;
+	struct ieee80211_key __rcu *key;
 	struct rate_control_ref *rate_ctrl;
 	void *rate_ctrl_priv;
 	spinlock_t lock;
diff --git a/net/netlabel/netlabel_domainhash.c b/net/netlabel/netlabel_domainhash.c
index d37b7f8..f6803cf 100644
--- a/net/netlabel/netlabel_domainhash.c
+++ b/net/netlabel/netlabel_domainhash.c
@@ -57,8 +57,8 @@ static DEFINE_SPINLOCK(netlbl_domhsh_lock);
 #define netlbl_domhsh_rcu_deref(p) \
 	rcu_dereference_check(p, rcu_read_lock_held() || \
 				 lockdep_is_held(&netlbl_domhsh_lock))
-static struct netlbl_domhsh_tbl *netlbl_domhsh = NULL;
-static struct netlbl_dom_map *netlbl_domhsh_def = NULL;
+static struct netlbl_domhsh_tbl __rcu *netlbl_domhsh = NULL;
+static struct netlbl_dom_map __rcu *netlbl_domhsh_def = NULL;
 
 /*
  * Domain Hash Table Helper Functions
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index e2b0a68..b32078b 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -118,8 +118,8 @@ static DEFINE_SPINLOCK(netlbl_unlhsh_lock);
 #define netlbl_unlhsh_rcu_deref(p) \
 	rcu_dereference_check(p, rcu_read_lock_held() || \
 				 lockdep_is_held(&netlbl_unlhsh_lock))
-static struct netlbl_unlhsh_tbl *netlbl_unlhsh = NULL;
-static struct netlbl_unlhsh_iface *netlbl_unlhsh_def = NULL;
+static struct netlbl_unlhsh_tbl __rcu *netlbl_unlhsh = NULL;
+static struct netlbl_unlhsh_iface __rcu *netlbl_unlhsh_def = NULL;
 
 /* Accept unlabeled packets flag */
 static u8 netlabel_unlabel_acceptflg = 0;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index a2eb965..6b9606a 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -119,7 +119,7 @@ struct nl_pid_hash {
 struct netlink_table {
 	struct nl_pid_hash hash;
 	struct hlist_head mc_list;
-	unsigned long *listeners;
+	unsigned long __rcu *listeners;
 	unsigned int nl_nonroot;
 	unsigned int groups;
 	struct mutex *cb_mutex;
diff --git a/net/phonet/af_phonet.c b/net/phonet/af_phonet.c
index 73aee7f..e3baaa1 100644
--- a/net/phonet/af_phonet.c
+++ b/net/phonet/af_phonet.c
@@ -35,7 +35,7 @@
 #include <net/phonet/pn_dev.h>
 
 /* Transport protocol registration */
-static struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
+static struct phonet_protocol __rcu *proto_tab[PHONET_NPROTO] __read_mostly;
 
 static struct phonet_protocol *phonet_proto_get(int protocol)
 {
diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
index c33da65..d1dfbad 100644
--- a/net/phonet/pn_dev.c
+++ b/net/phonet/pn_dev.c
@@ -36,7 +36,7 @@
 
 struct phonet_routes {
 	struct mutex		lock;
-	struct net_device	*table[64];
+	struct net_device __rcu	*table[64];
 };
 
 struct phonet_net {
diff --git a/net/socket.c b/net/socket.c
index 367d547..55c4853 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -156,7 +156,7 @@ static const struct file_operations socket_file_ops = {
  */
 
 static DEFINE_SPINLOCK(net_family_lock);
-static const struct net_proto_family *net_families[NPROTO] __read_mostly;
+static const struct net_proto_family __rcu *net_families[NPROTO] __read_mostly;
 
 /*
  *	Statistics counters of the socket lists
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 18/30] kvm: more __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@relay.de.ibm.com>

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |    2 +-
 include/linux/kvm_host.h        |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 76f5483..66524cd 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -378,7 +378,7 @@ struct kvm_mem_aliases {
 };
 
 struct kvm_arch {
-	struct kvm_mem_aliases *aliases;
+	struct kvm_mem_aliases __rcu *aliases;
 
 	unsigned int n_free_mmu_pages;
 	unsigned int n_requested_mmu_pages;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b34b1b4..b1964a8 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -175,7 +175,7 @@ struct kvm {
 	raw_spinlock_t requests_lock;
 	struct mutex slots_lock;
 	struct mm_struct *mm; /* userspace tied to this vm */
-	struct kvm_memslots *memslots;
+	struct kvm_memslots __rcu *memslots;
 	struct srcu_struct srcu;
 #ifdef CONFIG_KVM_APIC_ARCHITECTURE
 	u32 bsp_vcpu_id;
@@ -185,7 +185,7 @@ struct kvm {
 	atomic_t online_vcpus;
 	struct list_head vm_list;
 	struct mutex lock;
-	struct kvm_io_bus *buses[KVM_NR_BUSES];
+	struct kvm_io_bus __rcu *buses[KVM_NR_BUSES];
 #ifdef CONFIG_HAVE_KVM_EVENTFD
 	struct {
 		spinlock_t        lock;
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 19/30] vhost: add __rcu annotations

[Paul E. McKenney]

From: Arnd Bergmann <arnd@relay.de.ibm.com>

Also add rcu_dreference_protected() for code paths where locks are held.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
---
 drivers/vhost/net.c   |   15 +++++++++++----
 drivers/vhost/vhost.c |   29 +++++++++++++++++++++++------
 drivers/vhost/vhost.h |   11 ++++++++---
 3 files changed, 42 insertions(+), 13 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index df5b6b9..e044dd0 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -110,7 +110,9 @@ static void handle_tx(struct vhost_net *net)
 	size_t len, total_len = 0;
 	int err, wmem;
 	size_t hdr_size;
-	struct socket *sock = rcu_dereference(vq->private_data);
+	struct socket *sock;
+
+	sock = rcu_dereference_check(vq->private_data, in_vhost_workqueue());
 	if (!sock)
 		return;
 
@@ -364,7 +366,10 @@ static void vhost_net_disable_vq(struct vhost_net *n,
 static void vhost_net_enable_vq(struct vhost_net *n,
 				struct vhost_virtqueue *vq)
 {
-	struct socket *sock = vq->private_data;
+	struct socket *sock;
+
+	sock = rcu_dereference_protected(vq->private_data,
+					 lockdep_is_held(&vq->mutex));
 	if (!sock)
 		return;
 	if (vq == n->vqs + VHOST_NET_VQ_TX) {
@@ -380,7 +385,8 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 	struct socket *sock;
 
 	mutex_lock(&vq->mutex);
-	sock = vq->private_data;
+	sock = rcu_dereference_protected(vq->private_data,
+					 lockdep_is_held(&vq->mutex));
 	vhost_net_disable_vq(n, vq);
 	rcu_assign_pointer(vq->private_data, NULL);
 	mutex_unlock(&vq->mutex);
@@ -518,7 +524,8 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 	}
 
 	/* start polling new socket */
-	oldsock = vq->private_data;
+	oldsock = rcu_dereference_protected(vq->private_data,
+					    lockdep_is_held(&vq->mutex));
 	if (sock == oldsock)
 		goto done;
 
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 3b83382..aa7603a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -39,6 +39,13 @@ enum {
 
 static struct workqueue_struct *vhost_workqueue;
 
+#ifdef CONFIG_PROVE_RCU
+int in_vhost_workqueue(void)
+{
+	return in_workqueue_context(vhost_workqueue);
+}
+#endif /* #ifdef CONFIG_PROVE_RCU */
+
 static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh,
 			    poll_table *pt)
 {
@@ -180,7 +187,7 @@ long vhost_dev_reset_owner(struct vhost_dev *dev)
 	vhost_dev_cleanup(dev);
 
 	memory->nregions = 0;
-	dev->memory = memory;
+	RCU_INIT_POINTER(dev->memory, memory);
 	return 0;
 }
 
@@ -212,8 +219,9 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
 		fput(dev->log_file);
 	dev->log_file = NULL;
 	/* No one will access memory at this point */
-	kfree(dev->memory);
-	dev->memory = NULL;
+	kfree(rcu_dereference_protected(dev->memory,
+					lockdep_is_held(&dev->mutex)));
+	RCU_INIT_POINTER(dev->memory, NULL);
 	if (dev->mm)
 		mmput(dev->mm);
 	dev->mm = NULL;
@@ -294,14 +302,22 @@ static int vq_access_ok(unsigned int num,
 /* Caller should have device mutex but not vq mutex */
 int vhost_log_access_ok(struct vhost_dev *dev)
 {
-	return memory_access_ok(dev, dev->memory, 1);
+	struct vhost_memory *mp;
+
+	mp = rcu_dereference_protected(dev->memory,
+				       lockdep_is_held(&dev->mutex));
+	return memory_access_ok(dev, mp, 1);
 }
 
 /* Verify access for write logging. */
 /* Caller should have vq mutex and device mutex */
 static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base)
 {
-	return vq_memory_access_ok(log_base, vq->dev->memory,
+	struct vhost_memory *mp;
+
+	mp = rcu_dereference_protected(vq->dev->memory,
+				       lockdep_is_held(&vq->mutex));
+	return vq_memory_access_ok(log_base, mp,
 			    vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) &&
 		(!vq->log_used || log_access_ok(log_base, vq->log_addr,
 					sizeof *vq->used +
@@ -341,7 +357,8 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
 		kfree(newmem);
 		return -EFAULT;
 	}
-	oldmem = d->memory;
+	oldmem = rcu_dereference_protected(d->memory,
+					   lockdep_is_held(&d->mutex));
 	rcu_assign_pointer(d->memory, newmem);
 	synchronize_rcu();
 	kfree(oldmem);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 44591ba..48fb0ff 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -92,7 +92,7 @@ struct vhost_virtqueue {
 	 * work item execution acts instead of rcu_read_lock() and the end of
 	 * work item execution acts instead of rcu_read_lock().
 	 * Writers use virtqueue mutex. */
-	void *private_data;
+	void __rcu *private_data;
 	/* Log write descriptors */
 	void __user *log_base;
 	struct vhost_log log[VHOST_NET_MAX_SG];
@@ -102,7 +102,7 @@ struct vhost_dev {
 	/* Readers use RCU to access memory table pointer
 	 * log base pointer and features.
 	 * Writers use mutex below.*/
-	struct vhost_memory *memory;
+	struct vhost_memory __rcu *memory;
 	struct mm_struct *mm;
 	struct mutex mutex;
 	unsigned acked_features;
@@ -112,6 +112,7 @@ struct vhost_dev {
 	struct eventfd_ctx *log_ctx;
 };
 
+int in_vhost_workqueue(void);
 long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
 long vhost_dev_check_owner(struct vhost_dev *);
 long vhost_dev_reset_owner(struct vhost_dev *);
@@ -154,7 +155,11 @@ enum {
 
 static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
 {
-	unsigned acked_features = rcu_dereference(dev->acked_features);
+	unsigned acked_features;
+
+	acked_features =
+		rcu_dereference_index_check(dev->acked_features,
+					    lockdep_is_held(&dev->mutex));
 	return acked_features & (1 << bit);
 }
 
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 20/30] Update documentation to note the passage of INIT_RCU_HEAD()

[Paul E. McKenney]

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 Documentation/DocBook/kernel-locking.tmpl |    8 --------
 1 files changed, 0 insertions(+), 8 deletions(-)

diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl
index 084f6ad..e6cc574 100644
--- a/Documentation/DocBook/kernel-locking.tmpl
+++ b/Documentation/DocBook/kernel-locking.tmpl
@@ -1725,14 +1725,6 @@ the amount of locking which needs to be done.
          if (++cache_num > MAX_CACHE_SIZE) {
                  struct object *i, *outcast = NULL;
                  list_for_each_entry(i, &amp;cache, list) {
-@@ -85,6 +94,7 @@
-         obj-&gt;popularity = 0;
-         atomic_set(&amp;obj-&gt;refcnt, 1); /* The cache holds a reference */
-         spin_lock_init(&amp;obj-&gt;lock);
-+        INIT_RCU_HEAD(&amp;obj-&gt;rcu);
-
-         spin_lock_irqsave(&amp;cache_lock, flags);
-         __cache_add(obj);
 @@ -104,12 +114,11 @@
  struct object *cache_find(int id)
  {
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 21/30] Update call_rcu() usage, add synchronize_rcu()

[Paul E. McKenney]

Reported-by: Kyle Hubert <khubert@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 Documentation/DocBook/kernel-locking.tmpl |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl
index e6cc574..ed64d22 100644
--- a/Documentation/DocBook/kernel-locking.tmpl
+++ b/Documentation/DocBook/kernel-locking.tmpl
@@ -1645,7 +1645,9 @@ the amount of locking which needs to be done.
       all the readers who were traversing the list when we deleted the
       element are finished.  We use <function>call_rcu()</function> to
       register a callback which will actually destroy the object once
-      the readers are finished.
+      all pre-existing readers are finished.  Alternatively,
+      <function>synchronize_rcu()</function> may be used to block until
+      all pre-existing are finished.
     </para>
     <para>
       But how does Read Copy Update know when the readers are
@@ -1714,7 +1716,7 @@ the amount of locking which needs to be done.
 -        object_put(obj);
 +        list_del_rcu(&amp;obj-&gt;list);
          cache_num--;
-+        call_rcu(&amp;obj-&gt;rcu, cache_delete_rcu, obj);
++        call_rcu(&amp;obj-&gt;rcu, cache_delete_rcu);
  }
 
  /* Must be holding cache_lock */
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 22/30] rcu: make CPU stall warning timeout configurable

[Paul E. McKenney]

Also set the default to 60 seconds, up from the previous hard-coded timeout
of 10 seconds.  This allows people who care to set short timeouts, while
avoiding people with unusual configurations (make randconfig!!!) from being
bothered with spurious CPU stall warnings.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcutree.h  |    5 +++--
 lib/Kconfig.debug |   11 +++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 14c040b..5d68e17 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -254,9 +254,10 @@ struct rcu_data {
 #define RCU_STALL_DELAY_DELTA	       0
 #endif
 
-#define RCU_SECONDS_TILL_STALL_CHECK   (10 * HZ + RCU_STALL_DELAY_DELTA)
+#define RCU_SECONDS_TILL_STALL_CHECK   (CONFIG_RCU_CPU_STALL_TIMEOUT * HZ + \
+					RCU_STALL_DELAY_DELTA)
 						/* for rsp->jiffies_stall */
-#define RCU_SECONDS_TILL_STALL_RECHECK (30 * HZ + RCU_STALL_DELAY_DELTA)
+#define RCU_SECONDS_TILL_STALL_RECHECK (3 * RCU_SECONDS_TILL_STALL_CHECK + 30)
 						/* for rsp->jiffies_stall */
 #define RCU_STALL_RAT_DELAY		2	/* Allow other CPUs time */
 						/*  to take at least one */
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index a8a272a..af8b9c5 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -821,6 +821,17 @@ config RCU_CPU_STALL_DETECTOR
 
 	  Say Y if you are unsure.
 
+config RCU_CPU_STALL_TIMEOUT
+	int "RCU CPU stall timeout in seconds"
+	depends on RCU_CPU_STALL_DETECTOR
+	range 3 300
+	default 60
+	help
+	  If a given RCU grace period extends more than the specified
+	  number of seconds, a CPU stall warning is printed.  If the
+	  RCU grace period persists, additional CPU stall warnings are
+	  printed at more widely spaced intervals.
+
 config RCU_CPU_STALL_VERBOSE
 	bool "Print additional per-task information for RCU_CPU_STALL_DETECTOR"
 	depends on RCU_CPU_STALL_DETECTOR && TREE_PREEMPT_RCU
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 23/30] rcu head remove init

[Paul E. McKenney]

From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

RCU heads really don't need to be initialized. Their state before call_rcu()
really does not matter.

We need to keep init/destroy_rcu_head_on_stack() though, since we want
debugobjects to be able to keep track of these objects.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: David S. Miller <davem@davemloft.net>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: akpm@linux-foundation.org
CC: mingo@elte.hu
CC: laijs@cn.fujitsu.com
CC: dipankar@in.ibm.com
CC: josh@joshtriplett.org
CC: dvhltc@us.ibm.com
CC: niv@us.ibm.com
CC: tglx@linutronix.de
CC: peterz@infradead.org
CC: rostedt@goodmis.org
CC: Valdis.Kletnieks@vt.edu
CC: dhowells@redhat.com
CC: eric.dumazet@gmail.com
CC: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/linux/rcupdate.h |    6 ------
 1 files changed, 0 insertions(+), 6 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index b973dea..0ce0f05 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -75,12 +75,6 @@ extern void rcu_init(void);
 #error "Unknown RCU implementation specified to kernel configuration"
 #endif
 
-#define RCU_HEAD_INIT	{ .next = NULL, .func = NULL }
-#define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT
-#define INIT_RCU_HEAD(ptr) do { \
-       (ptr)->next = NULL; (ptr)->func = NULL; \
-} while (0)
-
 /*
  * init_rcu_head_on_stack()/destroy_rcu_head_on_stack() are needed for dynamic
  * initialization and destruction of rcu_head on the stack. rcu_head structures
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 24/30] rcu: add shiny new debug assists to Documentation/RCU/checklist.txt

[Paul E. McKenney]

Add a section describing PROVE_RCU, DEBUG_OBJECTS_RCU_HEAD, and
the __rcu sparse checking to the RCU checklist.

Suggested-by: David Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 Documentation/RCU/checklist.txt |   23 +++++++++++++++++++++++
 1 files changed, 23 insertions(+), 0 deletions(-)

diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index 790d1a8..c7c6788 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -365,3 +365,26 @@ over a rather long period of time, but improvements are always welcome!
 	and the compiler to freely reorder code into and out of RCU
 	read-side critical sections.  It is the responsibility of the
 	RCU update-side primitives to deal with this.
+
+17.	Use CONFIG_PROVE_RCU, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and
+	the __rcu sparse checks to validate your RCU code.  These
+	can help find problems as follows:
+
+	CONFIG_PROVE_RCU: check that accesses to RCU-protected data
+		structures are carried out under the proper RCU
+		read-side critical section, while holding the right
+		combination of locks, or whatever other conditions
+		are appropriate.
+
+	CONFIG_DEBUG_OBJECTS_RCU_HEAD: check that you don't pass the
+		same object to call_rcu() (or friends) before an RCU
+		grace period has elapsed since the last time that you
+		passed that same object to call_rcu() (or friends).
+
+	__rcu sparse checks: tag the pointer to the RCU-protected data
+		structure with __rcu, and sparse will warn you if you
+		access that pointer without the services of one of the
+		variants of rcu_dereference().
+
+	These debugging aids can help you find problems that are
+	otherwise extremely difficult to spot.
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 25/30] rcutorture: add random preemption

[Paul E. McKenney]

From: Lai Jiangshan <laijs@cn.fujitsu.com>

Add random preemption to help we to torture the preemptable rcu.

srcu_read_delay() also calls rcu_read_delay() for shorter delays.

Added comment to preempt_schedule() call indicating that no quiescent
states happen if preemption is disabled.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcutorture.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c
index 6535ac8..430cb7f 100644
--- a/kernel/rcutorture.c
+++ b/kernel/rcutorture.c
@@ -304,6 +304,10 @@ static void rcu_read_delay(struct rcu_random_state *rrsp)
 		mdelay(longdelay_ms);
 	if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 		udelay(shortdelay_us);
+#ifdef CONFIG_PREEMPT
+	if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
+		preempt_schedule();  /* No QS if preempt_disable() in effect */
+#endif
 }
 
 static void rcu_torture_read_unlock(int idx) __releases(RCU)
@@ -537,6 +541,8 @@ static void srcu_read_delay(struct rcu_random_state *rrsp)
 	delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 	if (!delay)
 		schedule_timeout_interruptible(longdelay);
+	else
+		rcu_read_delay(rrsp);
 }
 
 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 26/30] rcu: simplify the usage of percpu data

[Paul E. McKenney]

From: Lai Jiangshan <laijs@cn.fujitsu.com>

&percpu_data is compatible with allocated percpu data.

And we use it and remove the "->rda[NR_CPUS]" array, saving significant
storage on systems with large numbers of CPUs.  This does add an additional
level of indirection and thus an additional cache line referenced, but
because ->rda is not used on the read side, this is OK.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcutree.c        |   42 +++++++++++++++---------------------------
 kernel/rcutree.h        |    2 +-
 kernel/rcutree_plugin.h |    4 ++--
 3 files changed, 18 insertions(+), 30 deletions(-)

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index d5bc439..5b1c3c2 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -712,7 +712,7 @@ static void
 rcu_start_gp(struct rcu_state *rsp, unsigned long flags)
 	__releases(rcu_get_root(rsp)->lock)
 {
-	struct rcu_data *rdp = rsp->rda[smp_processor_id()];
+	struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
 	struct rcu_node *rnp = rcu_get_root(rsp);
 
 	if (!cpu_needs_another_gp(rsp, rdp) || rsp->fqs_active) {
@@ -960,7 +960,7 @@ rcu_check_quiescent_state(struct rcu_state *rsp, struct rcu_data *rdp)
 static void rcu_send_cbs_to_orphanage(struct rcu_state *rsp)
 {
 	int i;
-	struct rcu_data *rdp = rsp->rda[smp_processor_id()];
+	struct rcu_data *rdp = this_cpu_ptr(rsp->rda);
 
 	if (rdp->nxtlist == NULL)
 		return;  /* irqs disabled, so comparison is stable. */
@@ -984,7 +984,7 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
 	struct rcu_data *rdp;
 
 	raw_spin_lock_irqsave(&rsp->onofflock, flags);
-	rdp = rsp->rda[smp_processor_id()];
+	rdp = this_cpu_ptr(rsp->rda);
 	if (rsp->orphan_cbs_list == NULL) {
 		raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
 		return;
@@ -1007,7 +1007,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
 	unsigned long flags;
 	unsigned long mask;
 	int need_report = 0;
-	struct rcu_data *rdp = rsp->rda[cpu];
+	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
 	struct rcu_node *rnp;
 
 	/* Exclude any attempts to start a new grace period. */
@@ -1226,7 +1226,8 @@ static void force_qs_rnp(struct rcu_state *rsp, int (*f)(struct rcu_data *))
 		cpu = rnp->grplo;
 		bit = 1;
 		for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
-			if ((rnp->qsmask & bit) != 0 && f(rsp->rda[cpu]))
+			if ((rnp->qsmask & bit) != 0 &&
+			    f(per_cpu_ptr(rsp->rda, cpu)))
 				mask |= bit;
 		}
 		if (mask != 0) {
@@ -1402,7 +1403,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
 	 * a quiescent state betweentimes.
 	 */
 	local_irq_save(flags);
-	rdp = rsp->rda[smp_processor_id()];
+	rdp = this_cpu_ptr(rsp->rda);
 	rcu_process_gp_end(rsp, rdp);
 	check_for_new_grace_period(rsp, rdp);
 
@@ -1701,7 +1702,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
 {
 	unsigned long flags;
 	int i;
-	struct rcu_data *rdp = rsp->rda[cpu];
+	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
 	struct rcu_node *rnp = rcu_get_root(rsp);
 
 	/* Set up local state, ensuring consistent view of global state. */
@@ -1729,7 +1730,7 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptable)
 {
 	unsigned long flags;
 	unsigned long mask;
-	struct rcu_data *rdp = rsp->rda[cpu];
+	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
 	struct rcu_node *rnp = rcu_get_root(rsp);
 
 	/* Set up local state, ensuring consistent view of global state. */
@@ -1865,7 +1866,8 @@ static void __init rcu_init_levelspread(struct rcu_state *rsp)
 /*
  * Helper function for rcu_init() that initializes one rcu_state structure.
  */
-static void __init rcu_init_one(struct rcu_state *rsp)
+static void __init rcu_init_one(struct rcu_state *rsp,
+		struct rcu_data __percpu *rda)
 {
 	static char *buf[] = { "rcu_node_level_0",
 			       "rcu_node_level_1",
@@ -1918,37 +1920,23 @@ static void __init rcu_init_one(struct rcu_state *rsp)
 		}
 	}
 
+	rsp->rda = rda;
 	rnp = rsp->level[NUM_RCU_LVLS - 1];
 	for_each_possible_cpu(i) {
 		while (i > rnp->grphi)
 			rnp++;
-		rsp->rda[i]->mynode = rnp;
+		per_cpu_ptr(rsp->rda, i)->mynode = rnp;
 		rcu_boot_init_percpu_data(i, rsp);
 	}
 }
 
-/*
- * Helper macro for __rcu_init() and __rcu_init_preempt().  To be used
- * nowhere else!  Assigns leaf node pointers into each CPU's rcu_data
- * structure.
- */
-#define RCU_INIT_FLAVOR(rsp, rcu_data) \
-do { \
-	int i; \
-	\
-	for_each_possible_cpu(i) { \
-		(rsp)->rda[i] = &per_cpu(rcu_data, i); \
-	} \
-	rcu_init_one(rsp); \
-} while (0)
-
 void __init rcu_init(void)
 {
 	int cpu;
 
 	rcu_bootup_announce();
-	RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data);
-	RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data);
+	rcu_init_one(&rcu_sched_state, &rcu_sched_data);
+	rcu_init_one(&rcu_bh_state, &rcu_bh_data);
 	__rcu_init_preempt();
 	open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
 
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 5d68e17..183ebf4 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -284,7 +284,7 @@ struct rcu_state {
 	struct rcu_node *level[NUM_RCU_LVLS];	/* Hierarchy levels. */
 	u32 levelcnt[MAX_RCU_LVLS + 1];		/* # nodes in each level. */
 	u8 levelspread[NUM_RCU_LVLS];		/* kids/node in each level. */
-	struct rcu_data *rda[NR_CPUS];		/* array of rdp pointers. */
+	struct rcu_data __percpu *rda;		/* pointer of percu rcu_data. */
 
 	/* The following fields are guarded by the root rcu_node's lock. */
 
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 0e4f420..9906f85 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -154,7 +154,7 @@ static void rcu_preempt_note_context_switch(int cpu)
 	    (t->rcu_read_unlock_special & RCU_READ_UNLOCK_BLOCKED) == 0) {
 
 		/* Possibly blocking in an RCU read-side critical section. */
-		rdp = rcu_preempt_state.rda[cpu];
+		rdp = per_cpu_ptr(rcu_preempt_state.rda, cpu);
 		rnp = rdp->mynode;
 		raw_spin_lock_irqsave(&rnp->lock, flags);
 		t->rcu_read_unlock_special |= RCU_READ_UNLOCK_BLOCKED;
@@ -771,7 +771,7 @@ static void rcu_preempt_send_cbs_to_orphanage(void)
  */
 static void __init __rcu_init_preempt(void)
 {
-	RCU_INIT_FLAVOR(&rcu_preempt_state, rcu_preempt_data);
+	rcu_init_one(&rcu_preempt_state, &rcu_preempt_data);
 }
 
 /*
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 27/30] rcu: apply ->rda changes to rcutree_trace.c

[Paul E. McKenney]

The print_rcu_pendings() function used the ->rda[] array, so this
commit makes it instead use per_cpu_ptr().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcutree_trace.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index 36c95b4..458e032 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -262,7 +262,7 @@ static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
 	struct rcu_data *rdp;
 
 	for_each_possible_cpu(cpu) {
-		rdp = rsp->rda[cpu];
+		rdp = per_cpu_ptr(rsp->rda, cpu);
 		if (rdp->beenonline)
 			print_one_rcu_pending(m, rdp);
 	}
-- 
1.7.0.6

Re: [PATCH RFC tip/core/rcu 27/30] rcu: apply ->rda changes to rcutree_trace.c

[Josh Triplett]

On Wed, Jul 14, 2010 at 01:10:01PM -0700, Paul E. McKenney wrote:
> The print_rcu_pendings() function used the ->rda[] array, so this
> commit makes it instead use per_cpu_ptr().
> 
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
>  kernel/rcutree_trace.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
> index 36c95b4..458e032 100644
> --- a/kernel/rcutree_trace.c
> +++ b/kernel/rcutree_trace.c
> @@ -262,7 +262,7 @@ static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
>  	struct rcu_data *rdp;
>  
>  	for_each_possible_cpu(cpu) {
> -		rdp = rsp->rda[cpu];
> +		rdp = per_cpu_ptr(rsp->rda, cpu);
>  		if (rdp->beenonline)
>  			print_one_rcu_pending(m, rdp);
>  	}

For the final version of this patchset, this should get squashed into
the previous patch, right?  Otherwise, the state after the previous
patch but before this one won't compile.

- Josh Triplett

Re: [PATCH RFC tip/core/rcu 27/30] rcu: apply ->rda changes to rcutree_trace.c

[Paul E. McKenney]

On Wed, Jul 14, 2010 at 02:12:31PM -0700, Josh Triplett wrote:
> On Wed, Jul 14, 2010 at 01:10:01PM -0700, Paul E. McKenney wrote:
> > The print_rcu_pendings() function used the ->rda[] array, so this
> > commit makes it instead use per_cpu_ptr().
> > 
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > ---
> >  kernel/rcutree_trace.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
> > index 36c95b4..458e032 100644
> > --- a/kernel/rcutree_trace.c
> > +++ b/kernel/rcutree_trace.c
> > @@ -262,7 +262,7 @@ static void print_rcu_pendings(struct seq_file *m, struct rcu_state *rsp)
> >  	struct rcu_data *rdp;
> >  
> >  	for_each_possible_cpu(cpu) {
> > -		rdp = rsp->rda[cpu];
> > +		rdp = per_cpu_ptr(rsp->rda, cpu);
> >  		if (rdp->beenonline)
> >  			print_one_rcu_pending(m, rdp);
> >  	}
> 
> For the final version of this patchset, this should get squashed into
> the previous patch, right?  Otherwise, the state after the previous
> patch but before this one won't compile.

Makes sense, given that the earlier patch has not yet gone upstream.

							Thanx, Paul

[PATCH RFC tip/core/rcu 28/30] rcu: rename __do_rcu_dereference_check() to rcu_lockdep_assert()

[Paul E. McKenney]

The __do_rcu_dereference_check() functionality needs to be exported,
so make a real name for it.  This allows RCU-lockdep assertions to
be used independent of rcu_dereference() and friends.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/linux/rcupdate.h |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 0ce0f05..508ebba 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -209,7 +209,11 @@ static inline int rcu_read_lock_sched_held(void)
 
 extern int rcu_my_thread_group_empty(void);
 
-#define __do_rcu_dereference_check(c)					\
+/**
+ * rcu_lockdep_assert - emit lockdep splat if specified condition not met
+ * @c: condition to check
+ */
+#define rcu_lockdep_assert(c)						\
 	do {								\
 		static bool __warned;					\
 		if (debug_lockdep_rcu_enabled() && !__warned && !(c)) {	\
@@ -220,7 +224,7 @@ extern int rcu_my_thread_group_empty(void);
 
 #else /* #ifdef CONFIG_PROVE_RCU */
 
-#define __do_rcu_dereference_check(c) do { } while (0)
+#define rcu_lockdep_assert(c) do { } while (0)
 
 #endif /* #else #ifdef CONFIG_PROVE_RCU */
 
@@ -241,14 +245,14 @@ extern int rcu_my_thread_group_empty(void);
 #define __rcu_dereference_check(p, c, space) \
 	({ \
 		typeof(*p) *_________p1 = (typeof(*p)*__force )ACCESS_ONCE(p); \
-		__do_rcu_dereference_check(c); \
+		rcu_lockdep_assert(c); \
 		(void) (((typeof (*p) space *)p) == p); \
 		smp_read_barrier_depends(); \
 		((typeof(*p) __force __kernel *)(_________p1)); \
 	})
 #define __rcu_dereference_protected(p, c, space) \
 	({ \
-		__do_rcu_dereference_check(c); \
+		rcu_lockdep_assert(c); \
 		(void) (((typeof (*p) space *)p) == p); \
 		((typeof(*p) __force __kernel *)(p)); \
 	})
@@ -256,7 +260,7 @@ extern int rcu_my_thread_group_empty(void);
 #define __rcu_dereference_index_check(p, c) \
 	({ \
 		typeof(p) _________p1 = ACCESS_ONCE(p); \
-		__do_rcu_dereference_check(c); \
+		rcu_lockdep_assert(c); \
 		smp_read_barrier_depends(); \
 		(_________p1); \
 	})
-- 
1.7.0.6

[PATCH RFC tip/core/rcu 29/30] rcu: add boot parameter to suppress RCU CPU stall warning messages

[Paul E. McKenney]

Although the RCU CPU stall warning messages are a very good way to alert
people to a problem, once alerted, it is sometimes helpful to shut them
off in order to avoid obscuring other messages that might be being used
to track down the problem.  Although you can rebuild the kernel with
CONFIG_RCU_CPU_STALL_DETECTOR=n, this is sometimes inconvenient.  This
commit therefore adds a boot parameter named "rcu_cpu_stall_suppress"
that shuts these messages off without requiring a rebuild (though a
reboot might be needed for those not brave enough to patch their kernel
while it is running).

This message-suppression was already in place for the panic case, so this
commit need only rename the variable and export it via module_param().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 kernel/rcutree.c |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 5b1c3c2..f3d5906 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -143,6 +143,11 @@ module_param(blimit, int, 0);
 module_param(qhimark, int, 0);
 module_param(qlowmark, int, 0);
 
+#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
+int rcu_cpu_stall_suppress __read_mostly;
+module_param(rcu_cpu_stall_suppress, int, 0);
+#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
+
 static void force_quiescent_state(struct rcu_state *rsp, int relaxed);
 static int rcu_pending(int cpu);
 
@@ -450,7 +455,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
 
 #ifdef CONFIG_RCU_CPU_STALL_DETECTOR
 
-int rcu_cpu_stall_panicking __read_mostly;
+int rcu_cpu_stall_suppress __read_mostly;
 
 static void record_gp_stall_check_time(struct rcu_state *rsp)
 {
@@ -530,7 +535,7 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 	long delta;
 	struct rcu_node *rnp;
 
-	if (rcu_cpu_stall_panicking)
+	if (rcu_cpu_stall_suppress)
 		return;
 	delta = jiffies - rsp->jiffies_stall;
 	rnp = rdp->mynode;
@@ -548,7 +553,7 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
 
 static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr)
 {
-	rcu_cpu_stall_panicking = 1;
+	rcu_cpu_stall_suppress = 1;
 	return NOTIFY_DONE;
 }
 
-- 
1.7.0.6

Re: [PATCH RFC tip/core/rcu 29/30] rcu: add boot parameter to suppress RCU CPU stall warning messages

[Josh Triplett]

On Wed, Jul 14, 2010 at 01:10:03PM -0700, Paul E. McKenney wrote:
> Although the RCU CPU stall warning messages are a very good way to alert
> people to a problem, once alerted, it is sometimes helpful to shut them
> off in order to avoid obscuring other messages that might be being used
> to track down the problem.  Although you can rebuild the kernel with
> CONFIG_RCU_CPU_STALL_DETECTOR=n, this is sometimes inconvenient.  This
> commit therefore adds a boot parameter named "rcu_cpu_stall_suppress"
> that shuts these messages off without requiring a rebuild (though a
> reboot might be needed for those not brave enough to patch their kernel
> while it is running).
> 
> This message-suppression was already in place for the panic case, so this
> commit need only rename the variable and export it via module_param().
> 
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
>  kernel/rcutree.c |   11 ++++++++---
>  1 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 5b1c3c2..f3d5906 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -143,6 +143,11 @@ module_param(blimit, int, 0);
>  module_param(qhimark, int, 0);
>  module_param(qlowmark, int, 0);
>  
> +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
> +int rcu_cpu_stall_suppress __read_mostly;
> +module_param(rcu_cpu_stall_suppress, int, 0);
> +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */

In theory, you could change the permissions on this module_param from 0
to 0644, making it appear under /sys as a writable file.  That would
allow changing it at runtime rather than just at boot time.  Looking at
the use of this variable, changing it dynamically should work.

- Josh Triplett

Re: [PATCH RFC tip/core/rcu 29/30] rcu: add boot parameter to suppress RCU CPU stall warning messages

[Paul E. McKenney]

On Wed, Jul 14, 2010 at 02:16:06PM -0700, Josh Triplett wrote:
> On Wed, Jul 14, 2010 at 01:10:03PM -0700, Paul E. McKenney wrote:
> > Although the RCU CPU stall warning messages are a very good way to alert
> > people to a problem, once alerted, it is sometimes helpful to shut them
> > off in order to avoid obscuring other messages that might be being used
> > to track down the problem.  Although you can rebuild the kernel with
> > CONFIG_RCU_CPU_STALL_DETECTOR=n, this is sometimes inconvenient.  This
> > commit therefore adds a boot parameter named "rcu_cpu_stall_suppress"
> > that shuts these messages off without requiring a rebuild (though a
> > reboot might be needed for those not brave enough to patch their kernel
> > while it is running).
> > 
> > This message-suppression was already in place for the panic case, so this
> > commit need only rename the variable and export it via module_param().
> > 
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> > ---
> >  kernel/rcutree.c |   11 ++++++++---
> >  1 files changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> > index 5b1c3c2..f3d5906 100644
> > --- a/kernel/rcutree.c
> > +++ b/kernel/rcutree.c
> > @@ -143,6 +143,11 @@ module_param(blimit, int, 0);
> >  module_param(qhimark, int, 0);
> >  module_param(qlowmark, int, 0);
> >  
> > +#ifdef CONFIG_RCU_CPU_STALL_DETECTOR
> > +int rcu_cpu_stall_suppress __read_mostly;
> > +module_param(rcu_cpu_stall_suppress, int, 0);
> > +#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
> 
> In theory, you could change the permissions on this module_param from 0
> to 0644, making it appear under /sys as a writable file.  That would
> allow changing it at runtime rather than just at boot time.  Looking at
> the use of this variable, changing it dynamically should work.

Will give it a try!

							Thanx, Paul

[PATCH RFC tip/core/rcu 30/30] rcu: improve kerneldoc for rcu_read_lock(), call_rcu(), and synchronize_rcu()

[Paul E. McKenney]

Make it explicit that new RCU read-side critical sections that start
after call_rcu() and synchronize_rcu() start might still be running
after the end of the relevant grace period.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
 include/linux/rcupdate.h |   16 +++++++++-------
 kernel/rcutree_plugin.h  |    8 +++++---
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 508ebba..27b44b3 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -444,7 +444,7 @@ extern int rcu_my_thread_group_empty(void);
  * until after the all the other CPUs exit their critical sections.
  *
  * Note, however, that RCU callbacks are permitted to run concurrently
- * with RCU read-side critical sections.  One way that this can happen
+ * with new RCU read-side critical sections.  One way that this can happen
  * is via the following sequence of events: (1) CPU 0 enters an RCU
  * read-side critical section, (2) CPU 1 invokes call_rcu() to register
  * an RCU callback, (3) CPU 0 exits the RCU read-side critical section,
@@ -602,11 +602,13 @@ extern void wakeme_after_rcu(struct rcu_head  *head);
 /**
  * call_rcu() - Queue an RCU callback for invocation after a grace period.
  * @head: structure to be used for queueing the RCU updates.
- * @func: actual update function to be invoked after the grace period
+ * @func: actual callback function to be invoked after the grace period
  *
- * The update function will be invoked some time after a full grace
- * period elapses, in other words after all currently executing RCU
- * read-side critical sections have completed.  RCU read-side critical
+ * The callback function will be invoked some time after a full grace
+ * period elapses, in other words after all pre-existing RCU read-side
+ * critical sections have completed.  However, the callback function
+ * might well execute concurrently with RCU read-side critical sections
+ * that started after call_rcu() was invoked.  RCU read-side critical
  * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
  * and may be nested.
  */
@@ -616,9 +618,9 @@ extern void call_rcu(struct rcu_head *head,
 /**
  * call_rcu_bh() - Queue an RCU for invocation after a quicker grace period.
  * @head: structure to be used for queueing the RCU updates.
- * @func: actual update function to be invoked after the grace period
+ * @func: actual callback function to be invoked after the grace period
  *
- * The update function will be invoked some time after a full grace
+ * The callback function will be invoked some time after a full grace
  * period elapses, in other words after all currently executing RCU
  * read-side critical sections have completed. call_rcu_bh() assumes
  * that the read-side critical sections end on completion of a softirq
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 9906f85..63bb771 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -546,9 +546,11 @@ EXPORT_SYMBOL_GPL(call_rcu);
  *
  * Control will return to the caller some time after a full grace
  * period has elapsed, in other words after all currently executing RCU
- * read-side critical sections have completed.  RCU read-side critical
- * sections are delimited by rcu_read_lock() and rcu_read_unlock(),
- * and may be nested.
+ * read-side critical sections have completed.  Note, however, that
+ * upon return from synchronize_rcu(), the caller might well be executing
+ * concurrently with new RCU read-side critical sections that began while
+ * synchronize_rcu() was waiting.  RCU read-side critical sections are
+ * delimited by rcu_read_lock() and rcu_read_unlock(), and may be nested.
  */
 void synchronize_rcu(void)
 {
-- 
1.7.0.6

Re: [PATCH RFC tip/core/rcu 0/30] RCU commits queued for 2.6.36/7

[Josh Triplett]

On Wed, Jul 14, 2010 at 01:09:45PM -0700, Paul E. McKenney wrote:
> This patchset shows the patches queued for 2.6.36/7.  These are not
> yet ready to move upstream due to dependencies on commits moving up other
> trees.  The patches are as follows:
> 
> 1-19.	These are the remaining patches implementing Arnd's sparse-checking
> 	work.  #1 needs to go up the networking tree, but
> 	will cause regressions until f5155b33277 ("rcu: add an
> 	rcu_dereference_index_check()") reaches mainline.  #2 depends
> 	on #1, and many of the later patches (#3-#30) depend on #2.
> 	Many of #3-#19 will go up non-tip trees.
> 20.	Update Documentation/RCU to remove the now-deprecated rcu_head
> 	initialization macros.
> 21.	Fix long-standing DocBook example showing long-dead three-argument
> 	variant of call_rcu().
> 22.	Make the CPU stall warning timeout configurable at build time
> 	with new RCU_CPU_STALL_TIMEOUT config parameter.
> 23.	Remove the now-deprecated rcu_head initialization macros.
> 	This depends on a couple of patches removing their use that
> 	are making their way up other maintainer trees.
> 24.	Document the new debug assists from Arnd, Mathieu, and myself.
> 25.	Add random preemption to rcutorture testing of preemptible
> 	RCU, courtesy of Lai Jiangshan.
> 26.	Remove TREE_RCU's ->rda[] array in favor of the new __percpu
> 	facility, also courtesy of Lai Jiangshan.
> 27.	Fixlet to #26 for RCU tracing.
> 28.	Rename __do_rcu_dereference_check() to rcu_lockdep_assert(),
> 	given that Tetsuo Handa has found outside-of-RCU use for this
> 	function.
> 29.	Add a boot parameter to suppress RCU CPU stall warnings.
> 30.	Update kerneldoc or rcu_read_lock(), call_rcu(), and
> 	synchronize_rcu().

I replied to patches 27 and 29 with suggested changes.  For all the
rest:

Reviewed-by: Josh Triplett <josh@joshtriplett.org>

- Josh Triplett

Re: [PATCH RFC tip/core/rcu 0/30] RCU commits queued for 2.6.36/7

[Paul E. McKenney]

On Wed, Jul 14, 2010 at 02:19:02PM -0700, Josh Triplett wrote:
> On Wed, Jul 14, 2010 at 01:09:45PM -0700, Paul E. McKenney wrote:
> > This patchset shows the patches queued for 2.6.36/7.  These are not
> > yet ready to move upstream due to dependencies on commits moving up other
> > trees.  The patches are as follows:
> > 
> > 1-19.	These are the remaining patches implementing Arnd's sparse-checking
> > 	work.  #1 needs to go up the networking tree, but
> > 	will cause regressions until f5155b33277 ("rcu: add an
> > 	rcu_dereference_index_check()") reaches mainline.  #2 depends
> > 	on #1, and many of the later patches (#3-#30) depend on #2.
> > 	Many of #3-#19 will go up non-tip trees.
> > 20.	Update Documentation/RCU to remove the now-deprecated rcu_head
> > 	initialization macros.
> > 21.	Fix long-standing DocBook example showing long-dead three-argument
> > 	variant of call_rcu().
> > 22.	Make the CPU stall warning timeout configurable at build time
> > 	with new RCU_CPU_STALL_TIMEOUT config parameter.
> > 23.	Remove the now-deprecated rcu_head initialization macros.
> > 	This depends on a couple of patches removing their use that
> > 	are making their way up other maintainer trees.
> > 24.	Document the new debug assists from Arnd, Mathieu, and myself.
> > 25.	Add random preemption to rcutorture testing of preemptible
> > 	RCU, courtesy of Lai Jiangshan.
> > 26.	Remove TREE_RCU's ->rda[] array in favor of the new __percpu
> > 	facility, also courtesy of Lai Jiangshan.
> > 27.	Fixlet to #26 for RCU tracing.
> > 28.	Rename __do_rcu_dereference_check() to rcu_lockdep_assert(),
> > 	given that Tetsuo Handa has found outside-of-RCU use for this
> > 	function.
> > 29.	Add a boot parameter to suppress RCU CPU stall warnings.
> > 30.	Update kerneldoc or rcu_read_lock(), call_rcu(), and
> > 	synchronize_rcu().
> 
> I replied to patches 27 and 29 with suggested changes.  For all the
> rest:
> 
> Reviewed-by: Josh Triplett <josh@joshtriplett.org>

Thank you very much for looking this over!

							Thanx, Paul