[PATCH tip/core/rcu 0/8] RCU list-traversal lockdep updates for v5.4

[PATCH tip/core/rcu 0/8] RCU list-traversal lockdep updates for v5.4

[Paul E. McKenney]

Hello!

This series provides enhancements to RCU pointer and list macros, all
courtesy of Joel Fernandes:

1.	Rename rcu_dereference_raw_notrace() to _check().

2.	Remove redundant debug_locks check in rcu_read_lock_sched_held().

3.	Add support for consolidated-RCU reader checking.

4.	Remove custom check for RCU readers.

5.	Add lockdep condition to fix for_each_entry().

6.	Convert to use built-in RCU list checking.

7.	Pass lockdep condition to pcm_mmcfg_list iterator.

8.	Use built-in RCU list checking for acpi_ioremaps list.

							Thanx, Paul

------------------------------------------------------------------------

 Documentation/RCU/Design/Requirements/Requirements.html |    2 
 arch/powerpc/include/asm/kvm_book3s_64.h                |    2 
 arch/x86/pci/mmconfig-shared.c                          |    5 -
 drivers/acpi/osl.c                                      |    6 -
 drivers/base/base.h                                     |    1 
 drivers/base/core.c                                     |   10 ++
 drivers/base/power/runtime.c                            |   15 ++-
 include/linux/rcu_sync.h                                |    4 
 include/linux/rculist.h                                 |   38 +++++++--
 include/linux/rcupdate.h                                |    9 +-
 kernel/rcu/Kconfig.debug                                |   11 ++
 kernel/rcu/update.c                                     |   67 ++++++++++------
 kernel/trace/ftrace_internal.h                          |    8 -
 kernel/trace/trace.c                                    |    4 
 net/ipv4/fib_frontend.c                                 |    3 
 15 files changed, 132 insertions(+), 53 deletions(-)

[PATCH tip/core/rcu 1/8] treewide: Rename rcu_dereference_raw_notrace() to _check()

[Paul E. McKenney]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

The rcu_dereference_raw_notrace() API name is confusing.  It is equivalent
to rcu_dereference_raw() except that it also does sparse pointer checking.

There are only a few users of rcu_dereference_raw_notrace(). This patches
renames all of them to be rcu_dereference_raw_check() with the "_check()"
indicating sparse checking.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
[ paulmck: Fix checkpatch warnings about parentheses. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 Documentation/RCU/Design/Requirements/Requirements.html | 2 +-
 arch/powerpc/include/asm/kvm_book3s_64.h                | 2 +-
 include/linux/rculist.h                                 | 6 +++---
 include/linux/rcupdate.h                                | 2 +-
 kernel/trace/ftrace_internal.h                          | 8 ++++----
 kernel/trace/trace.c                                    | 4 ++--
 6 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html
index 5a9238a2883c..bdbc84f1b949 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.html
+++ b/Documentation/RCU/Design/Requirements/Requirements.html
@@ -2512,7 +2512,7 @@ disabled across the entire RCU read-side critical section.
 <p>
 It is possible to use tracing on RCU code, but tracing itself
 uses RCU.
-For this reason, <tt>rcu_dereference_raw_notrace()</tt>
+For this reason, <tt>rcu_dereference_raw_check()</tt>
 is provided for use by tracing, which avoids the destructive
 recursion that could otherwise ensue.
 This API is also used by virtualization in some architectures,
diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index bb7c8cc77f1a..04b2b927bb5a 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -535,7 +535,7 @@ static inline void note_hpte_modification(struct kvm *kvm,
  */
 static inline struct kvm_memslots *kvm_memslots_raw(struct kvm *kvm)
 {
-	return rcu_dereference_raw_notrace(kvm->memslots[0]);
+	return rcu_dereference_raw_check(kvm->memslots[0]);
 }
 
 extern void kvmppc_mmu_debugfs_init(struct kvm *kvm);
diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index e91ec9ddcd30..932296144131 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -622,7 +622,7 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
  * as long as the traversal is guarded by rcu_read_lock().
  */
 #define hlist_for_each_entry_rcu(pos, head, member)			\
-	for (pos = hlist_entry_safe (rcu_dereference_raw(hlist_first_rcu(head)),\
+	for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\
 			typeof(*(pos)), member);			\
 		pos;							\
 		pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\
@@ -642,10 +642,10 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
  * not do any RCU debugging or tracing.
  */
 #define hlist_for_each_entry_rcu_notrace(pos, head, member)			\
-	for (pos = hlist_entry_safe (rcu_dereference_raw_notrace(hlist_first_rcu(head)),\
+	for (pos = hlist_entry_safe(rcu_dereference_raw_check(hlist_first_rcu(head)),\
 			typeof(*(pos)), member);			\
 		pos;							\
-		pos = hlist_entry_safe(rcu_dereference_raw_notrace(hlist_next_rcu(\
+		pos = hlist_entry_safe(rcu_dereference_raw_check(hlist_next_rcu(\
 			&(pos)->member)), typeof(*(pos)), member))
 
 /**
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 8f7167478c1d..bfcafbc1e301 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -476,7 +476,7 @@ do {									      \
  * The no-tracing version of rcu_dereference_raw() must not call
  * rcu_read_lock_held().
  */
-#define rcu_dereference_raw_notrace(p) __rcu_dereference_check((p), 1, __rcu)
+#define rcu_dereference_raw_check(p) __rcu_dereference_check((p), 1, __rcu)
 
 /**
  * rcu_dereference_protected() - fetch RCU pointer when updates prevented
diff --git a/kernel/trace/ftrace_internal.h b/kernel/trace/ftrace_internal.h
index 0515a2096f90..0456e0a3dab1 100644
--- a/kernel/trace/ftrace_internal.h
+++ b/kernel/trace/ftrace_internal.h
@@ -6,22 +6,22 @@
 
 /*
  * Traverse the ftrace_global_list, invoking all entries.  The reason that we
- * can use rcu_dereference_raw_notrace() is that elements removed from this list
+ * can use rcu_dereference_raw_check() is that elements removed from this list
  * are simply leaked, so there is no need to interact with a grace-period
- * mechanism.  The rcu_dereference_raw_notrace() calls are needed to handle
+ * mechanism.  The rcu_dereference_raw_check() calls are needed to handle
  * concurrent insertions into the ftrace_global_list.
  *
  * Silly Alpha and silly pointer-speculation compiler optimizations!
  */
 #define do_for_each_ftrace_op(op, list)			\
-	op = rcu_dereference_raw_notrace(list);			\
+	op = rcu_dereference_raw_check(list);			\
 	do
 
 /*
  * Optimized for just a single item in the list (as that is the normal case).
  */
 #define while_for_each_ftrace_op(op)				\
-	while (likely(op = rcu_dereference_raw_notrace((op)->next)) &&	\
+	while (likely(op = rcu_dereference_raw_check((op)->next)) &&	\
 	       unlikely((op) != &ftrace_list_end))
 
 extern struct ftrace_ops __rcu *ftrace_ops_list;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 525a97fbbc60..642474b26ba7 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2642,10 +2642,10 @@ static void ftrace_exports(struct ring_buffer_event *event)
 
 	preempt_disable_notrace();
 
-	export = rcu_dereference_raw_notrace(ftrace_exports_list);
+	export = rcu_dereference_raw_check(ftrace_exports_list);
 	while (export) {
 		trace_process_export(export, event);
-		export = rcu_dereference_raw_notrace(export->next);
+		export = rcu_dereference_raw_check(export->next);
 	}
 
 	preempt_enable_notrace();
-- 
2.17.1

[PATCH tip/core/rcu 2/8] rcu: Remove redundant debug_locks check in rcu_read_lock_sched_held()

[Paul E. McKenney]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

The debug_locks flag can never be true at the end of
rcu_read_lock_sched_held() because it is already checked by the earlier
call todebug_lockdep_rcu_enabled().   This commit therefore removes this
redundant check.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 kernel/rcu/update.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 61df2bf08563..9dd5aeef6e70 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -93,17 +93,13 @@ module_param(rcu_normal_after_boot, int, 0);
  */
 int rcu_read_lock_sched_held(void)
 {
-	int lockdep_opinion = 0;
-
 	if (!debug_lockdep_rcu_enabled())
 		return 1;
 	if (!rcu_is_watching())
 		return 0;
 	if (!rcu_lockdep_current_cpu_online())
 		return 0;
-	if (debug_locks)
-		lockdep_opinion = lock_is_held(&rcu_sched_lock_map);
-	return lockdep_opinion || !preemptible();
+	return lock_is_held(&rcu_sched_lock_map) || !preemptible();
 }
 EXPORT_SYMBOL(rcu_read_lock_sched_held);
 #endif
-- 
2.17.1

[PATCH tip/core/rcu 3/8] rcu: Add support for consolidated-RCU reader checking

[Paul E. McKenney]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

This commit adds RCU-reader checks to list_for_each_entry_rcu() and
hlist_for_each_entry_rcu().  These checks are optional, and are indicated
by a lockdep expression passed to a new optional argument to these two
macros.  If this optional lockdep expression is omitted, these two macros
act as before, checking for an RCU read-side critical section.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
[ paulmck: Update to eliminate return within macro. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 include/linux/rculist.h  | 32 +++++++++++++++++----
 include/linux/rcupdate.h |  7 +++++
 kernel/rcu/Kconfig.debug | 11 ++++++++
 kernel/rcu/update.c      | 61 ++++++++++++++++++++++++++++------------
 4 files changed, 88 insertions(+), 23 deletions(-)

diff --git a/include/linux/rculist.h b/include/linux/rculist.h
index 932296144131..4158b7212936 100644
--- a/include/linux/rculist.h
+++ b/include/linux/rculist.h
@@ -40,6 +40,24 @@ static inline void INIT_LIST_HEAD_RCU(struct list_head *list)
  */
 #define list_next_rcu(list)	(*((struct list_head __rcu **)(&(list)->next)))
 
+/*
+ * Check during list traversal that we are within an RCU reader
+ */
+
+#define check_arg_count_one(dummy)
+
+#ifdef CONFIG_PROVE_RCU_LIST
+#define __list_check_rcu(dummy, cond, extra...)				\
+	({								\
+	check_arg_count_one(extra);					\
+	RCU_LOCKDEP_WARN(!cond && !rcu_read_lock_any_held(),		\
+			 "RCU-list traversed in non-reader section!");	\
+	 })
+#else
+#define __list_check_rcu(dummy, cond, extra...)				\
+	({ check_arg_count_one(extra); })
+#endif
+
 /*
  * Insert a new entry between two known consecutive entries.
  *
@@ -343,14 +361,16 @@ static inline void list_splice_tail_init_rcu(struct list_head *list,
  * @pos:	the type * to use as a loop cursor.
  * @head:	the head for your list.
  * @member:	the name of the list_head within the struct.
+ * @cond:	optional lockdep expression if called from non-RCU protection.
  *
  * This list-traversal primitive may safely run concurrently with
  * the _rcu list-mutation primitives such as list_add_rcu()
  * as long as the traversal is guarded by rcu_read_lock().
  */
-#define list_for_each_entry_rcu(pos, head, member) \
-	for (pos = list_entry_rcu((head)->next, typeof(*pos), member); \
-		&pos->member != (head); \
+#define list_for_each_entry_rcu(pos, head, member, cond...)		\
+	for (__list_check_rcu(dummy, ## cond, 0),			\
+	     pos = list_entry_rcu((head)->next, typeof(*pos), member);	\
+		&pos->member != (head);					\
 		pos = list_entry_rcu(pos->member.next, typeof(*pos), member))
 
 /**
@@ -616,13 +636,15 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n,
  * @pos:	the type * to use as a loop cursor.
  * @head:	the head for your list.
  * @member:	the name of the hlist_node within the struct.
+ * @cond:	optional lockdep expression if called from non-RCU protection.
  *
  * This list-traversal primitive may safely run concurrently with
  * 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(pos, head, member)			\
-	for (pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\
+#define hlist_for_each_entry_rcu(pos, head, member, cond...)		\
+	for (__list_check_rcu(dummy, ## cond, 0),			\
+	     pos = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),\
 			typeof(*(pos)), member);			\
 		pos;							\
 		pos = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(\
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index bfcafbc1e301..80d6056f5855 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -221,6 +221,7 @@ int debug_lockdep_rcu_enabled(void);
 int rcu_read_lock_held(void);
 int rcu_read_lock_bh_held(void);
 int rcu_read_lock_sched_held(void);
+int rcu_read_lock_any_held(void);
 
 #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
@@ -241,6 +242,12 @@ static inline int rcu_read_lock_sched_held(void)
 {
 	return !preemptible();
 }
+
+static inline int rcu_read_lock_any_held(void)
+{
+	return !preemptible();
+}
+
 #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
 #ifdef CONFIG_PROVE_RCU
diff --git a/kernel/rcu/Kconfig.debug b/kernel/rcu/Kconfig.debug
index 5ec3ea4028e2..4aa02eee8f6c 100644
--- a/kernel/rcu/Kconfig.debug
+++ b/kernel/rcu/Kconfig.debug
@@ -8,6 +8,17 @@ menu "RCU Debugging"
 config PROVE_RCU
 	def_bool PROVE_LOCKING
 
+config PROVE_RCU_LIST
+	bool "RCU list lockdep debugging"
+	depends on PROVE_RCU && RCU_EXPERT
+	default n
+	help
+	  Enable RCU lockdep checking for list usages. By default it is
+	  turned off since there are several list RCU users that still
+	  need to be converted to pass a lockdep expression. To prevent
+	  false-positive splats, we keep it default disabled but once all
+	  users are converted, we can remove this config option.
+
 config TORTURE_TEST
 	tristate
 	default n
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 9dd5aeef6e70..aaa08d62ceb6 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -91,14 +91,29 @@ module_param(rcu_normal_after_boot, int, 0);
  * Similarly, we avoid claiming an SRCU read lock held if the current
  * CPU is offline.
  */
+static bool rcu_read_lock_held_common(bool *ret)
+{
+	if (!debug_lockdep_rcu_enabled()) {
+		*ret = 1;
+		return true;
+	}
+	if (!rcu_is_watching()) {
+		*ret = 0;
+		return true;
+	}
+	if (!rcu_lockdep_current_cpu_online()) {
+		*ret = 0;
+		return true;
+	}
+	return false;
+}
+
 int rcu_read_lock_sched_held(void)
 {
-	if (!debug_lockdep_rcu_enabled())
-		return 1;
-	if (!rcu_is_watching())
-		return 0;
-	if (!rcu_lockdep_current_cpu_online())
-		return 0;
+	bool ret;
+
+	if (rcu_read_lock_held_common(&ret))
+		return ret;
 	return lock_is_held(&rcu_sched_lock_map) || !preemptible();
 }
 EXPORT_SYMBOL(rcu_read_lock_sched_held);
@@ -257,12 +272,10 @@ NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled);
  */
 int rcu_read_lock_held(void)
 {
-	if (!debug_lockdep_rcu_enabled())
-		return 1;
-	if (!rcu_is_watching())
-		return 0;
-	if (!rcu_lockdep_current_cpu_online())
-		return 0;
+	bool ret;
+
+	if (rcu_read_lock_held_common(&ret))
+		return ret;
 	return lock_is_held(&rcu_lock_map);
 }
 EXPORT_SYMBOL_GPL(rcu_read_lock_held);
@@ -284,16 +297,28 @@ EXPORT_SYMBOL_GPL(rcu_read_lock_held);
  */
 int rcu_read_lock_bh_held(void)
 {
-	if (!debug_lockdep_rcu_enabled())
-		return 1;
-	if (!rcu_is_watching())
-		return 0;
-	if (!rcu_lockdep_current_cpu_online())
-		return 0;
+	bool ret;
+
+	if (rcu_read_lock_held_common(&ret))
+		return ret;
 	return in_softirq() || irqs_disabled();
 }
 EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held);
 
+int rcu_read_lock_any_held(void)
+{
+	bool ret;
+
+	if (rcu_read_lock_held_common(&ret))
+		return ret;
+	if (lock_is_held(&rcu_lock_map) ||
+	    lock_is_held(&rcu_bh_lock_map) ||
+	    lock_is_held(&rcu_sched_lock_map))
+		return 1;
+	return !preemptible();
+}
+EXPORT_SYMBOL_GPL(rcu_read_lock_any_held);
+
 #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
 
 /**
-- 
2.17.1

[PATCH tip/core/rcu 4/8] rcu/sync: Remove custom check for RCU readers

[Paul E. McKenney]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

The rcu/sync code currently does a special check for being in an RCU
read-side critical section.  With RCU consolidating flavors and the
generic helper added earlier in this series, this check is no longer need.
This commit switches to the generic helper, saving a couple of lines
of code.

Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 include/linux/rcu_sync.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h
index 9b83865d24f9..0027d4c8087c 100644
--- a/include/linux/rcu_sync.h
+++ b/include/linux/rcu_sync.h
@@ -31,9 +31,7 @@ struct rcu_sync {
  */
 static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
 {
-	RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&
-			 !rcu_read_lock_bh_held() &&
-			 !rcu_read_lock_sched_held(),
+	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
 			 "suspicious rcu_sync_is_idle() usage");
 	return !READ_ONCE(rsp->gp_state); /* GP_IDLE */
 }
-- 
2.17.1

[PATCH tip/core/rcu 5/8] ipv4: Add lockdep condition to fix for_each_entry()

[Paul E. McKenney]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

This commit applies the consolidated list_for_each_entry_rcu() support
for lockdep conditions.

Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 net/ipv4/fib_frontend.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index e8bc939b56dd..dde77f72e03e 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -124,7 +124,8 @@ struct fib_table *fib_get_table(struct net *net, u32 id)
 	h = id & (FIB_TABLE_HASHSZ - 1);
 
 	head = &net->ipv4.fib_table_hash[h];
-	hlist_for_each_entry_rcu(tb, head, tb_hlist) {
+	hlist_for_each_entry_rcu(tb, head, tb_hlist,
+				 lockdep_rtnl_is_held()) {
 		if (tb->tb_id == id)
 			return tb;
 	}
-- 
2.17.1

[PATCH tip/core/rcu 6/8] driver/core: Convert to use built-in RCU list checking

[Paul E. McKenney]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

This commit applies the consolidated hlist_for_each_entry_rcu() support
for lockdep conditions.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 drivers/base/base.h          |  1 +
 drivers/base/core.c          | 10 ++++++++++
 drivers/base/power/runtime.c | 15 ++++++++++-----
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/base/base.h b/drivers/base/base.h
index b405436ee28e..0d32544b6f91 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -165,6 +165,7 @@ static inline int devtmpfs_init(void) { return 0; }
 /* Device links support */
 extern int device_links_read_lock(void);
 extern void device_links_read_unlock(int idx);
+extern int device_links_read_lock_held(void);
 extern int device_links_check_suppliers(struct device *dev);
 extern void device_links_driver_bound(struct device *dev);
 extern void device_links_driver_cleanup(struct device *dev);
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 636058bbf48a..32cf83d1c744 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -68,6 +68,11 @@ void device_links_read_unlock(int idx)
 {
 	srcu_read_unlock(&device_links_srcu, idx);
 }
+
+int device_links_read_lock_held(void)
+{
+	return srcu_read_lock_held(&device_links_srcu);
+}
 #else /* !CONFIG_SRCU */
 static DECLARE_RWSEM(device_links_lock);
 
@@ -91,6 +96,11 @@ void device_links_read_unlock(int not_used)
 {
 	up_read(&device_links_lock);
 }
+
+int device_links_read_lock_held(void)
+{
+	return lock_is_held(&device_links_lock);
+}
 #endif /* !CONFIG_SRCU */
 
 /**
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index b75335508d2c..50def99df970 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -287,7 +287,8 @@ static int rpm_get_suppliers(struct device *dev)
 {
 	struct device_link *link;
 
-	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held()) {
 		int retval;
 
 		if (!(link->flags & DL_FLAG_PM_RUNTIME) ||
@@ -309,7 +310,8 @@ static void rpm_put_suppliers(struct device *dev)
 {
 	struct device_link *link;
 
-	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held()) {
 		if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 			continue;
 
@@ -1640,7 +1642,8 @@ void pm_runtime_clean_up_links(struct device *dev)
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
+	list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
+				device_links_read_lock_held()) {
 		if (link->flags & DL_FLAG_STATELESS)
 			continue;
 
@@ -1662,7 +1665,8 @@ void pm_runtime_get_suppliers(struct device *dev)
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held())
 		if (link->flags & DL_FLAG_PM_RUNTIME) {
 			link->supplier_preactivated = true;
 			refcount_inc(&link->rpm_active);
@@ -1683,7 +1687,8 @@ void pm_runtime_put_suppliers(struct device *dev)
 
 	idx = device_links_read_lock();
 
-	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
+				device_links_read_lock_held())
 		if (link->supplier_preactivated) {
 			link->supplier_preactivated = false;
 			if (refcount_dec_not_one(&link->rpm_active))
-- 
2.17.1

[PATCH tip/core/rcu 7/8] x86/pci: Pass lockdep condition to pcm_mmcfg_list iterator

[Paul E. McKenney]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

The pcm_mmcfg_list is traversed by list_for_each_entry_rcu() outside
of an RCU read-side critical section, which is safe because the
pci_mmcfg_lock is held.  This commit therefore adds a lockdep expression
to list_for_each_entry_rcu() in order t avoid lockdep warnings.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 arch/x86/pci/mmconfig-shared.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 7389db538c30..6fa42e9c4e6f 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -29,6 +29,7 @@
 static bool pci_mmcfg_running_state;
 static bool pci_mmcfg_arch_init_failed;
 static DEFINE_MUTEX(pci_mmcfg_lock);
+#define pci_mmcfg_lock_held() lock_is_held(&(pci_mmcfg_lock).dep_map)
 
 LIST_HEAD(pci_mmcfg_list);
 
@@ -54,7 +55,7 @@ static void list_add_sorted(struct pci_mmcfg_region *new)
 	struct pci_mmcfg_region *cfg;
 
 	/* keep list sorted by segment and starting bus number */
-	list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list) {
+	list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list, pci_mmcfg_lock_held()) {
 		if (cfg->segment > new->segment ||
 		    (cfg->segment == new->segment &&
 		     cfg->start_bus >= new->start_bus)) {
@@ -118,7 +119,7 @@ struct pci_mmcfg_region *pci_mmconfig_lookup(int segment, int bus)
 {
 	struct pci_mmcfg_region *cfg;
 
-	list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list)
+	list_for_each_entry_rcu(cfg, &pci_mmcfg_list, list, pci_mmcfg_lock_held())
 		if (cfg->segment == segment &&
 		    cfg->start_bus <= bus && bus <= cfg->end_bus)
 			return cfg;
-- 
2.17.1

[PATCH tip/core/rcu 8/8] acpi: Use built-in RCU list checking for acpi_ioremaps list

[Paul E. McKenney]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

This commit applies the consolidated list_for_each_entry_rcu() support
for lockdep conditions.

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
---
 drivers/acpi/osl.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 9c0edf2fc0dd..2f9d0d20b836 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/highmem.h>
+#include <linux/lockdep.h>
 #include <linux/pci.h>
 #include <linux/interrupt.h>
 #include <linux/kmod.h>
@@ -80,6 +81,7 @@ struct acpi_ioremap {
 
 static LIST_HEAD(acpi_ioremaps);
 static DEFINE_MUTEX(acpi_ioremap_lock);
+#define acpi_ioremap_lock_held() lock_is_held(&acpi_ioremap_lock.dep_map)
 
 static void __init acpi_request_region (struct acpi_generic_address *gas,
 	unsigned int length, char *desc)
@@ -206,7 +208,7 @@ acpi_map_lookup(acpi_physical_address phys, acpi_size size)
 {
 	struct acpi_ioremap *map;
 
-	list_for_each_entry_rcu(map, &acpi_ioremaps, list)
+	list_for_each_entry_rcu(map, &acpi_ioremaps, list, acpi_ioremap_lock_held())
 		if (map->phys <= phys &&
 		    phys + size <= map->phys + map->size)
 			return map;
@@ -249,7 +251,7 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
 {
 	struct acpi_ioremap *map;
 
-	list_for_each_entry_rcu(map, &acpi_ioremaps, list)
+	list_for_each_entry_rcu(map, &acpi_ioremaps, list, acpi_ioremap_lock_held())
 		if (map->virt <= virt &&
 		    virt + size <= map->virt + map->size)
 			return map;
-- 
2.17.1