From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca,
josh@joshtriplett.org, dvhltc@us.ibm.com, niv@us.ibm.com,
tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org,
Valdis.Kletnieks@vt.edu, dhowells@redhat.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: [PATCH tip/core/rcu 2/9] rcu: add lockdep-enabled variants of rcu_dereference()
Date: Thu, 14 Jan 2010 17:02:39 -0800 [thread overview]
Message-ID: <12635173661621-git-send-email-> (raw)
In-Reply-To: <20100115010157.GA28221@linux.vnet.ibm.com>
From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Make rcu_dereference() check for being in an RCU read-side critical
section, and create rcu_dereference_bh(), rcu_dereference_sched(), and
srcu_dereference() to check for the other flavors of RCU. Also create
rcu_dereference_raw() to avoid checking, and make rcu_dereference_check()
use rcu_dereference_raw().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcupdate.h | 41 ++++++++++++++++++++++++++++++++++-------
include/linux/srcu.h | 8 ++++++++
2 files changed, 42 insertions(+), 7 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index e3d37ef..839d296 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -184,12 +184,12 @@ static inline int rcu_read_lock_sched_held(void)
({ \
if (debug_locks) \
WARN_ON_ONCE(!(c)); \
- rcu_dereference(p); \
+ rcu_dereference_raw(p); \
})
#else /* #ifdef CONFIG_PROVE_RCU */
-#define rcu_dereference_check(p, c) rcu_dereference(p)
+#define rcu_dereference_check(p, c) rcu_dereference_raw(p)
#endif /* #else #ifdef CONFIG_PROVE_RCU */
@@ -325,22 +325,49 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
/**
- * rcu_dereference - fetch an RCU-protected pointer in an
- * RCU read-side critical section. This pointer may later
- * be safely dereferenced.
+ * rcu_dereference_raw - fetch an RCU-protected pointer
+ *
+ * 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(p) ({ \
+#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.
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index adbe167..3084f80 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -106,6 +106,14 @@ 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
+ *
+ * Makes rcu_dereference_check() do the dirty work.
+ */
+#define srcu_dereference(p, sp) \
+ rcu_dereference_check(p, srcu_read_lock_held(sp))
+
+/**
* srcu_read_lock - register a new reader for an SRCU-protected structure.
* @sp: srcu_struct in which to register the new reader.
*
--
1.5.2.5
next prev parent reply other threads:[~2010-01-15 1:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-15 1:01 [PATCH tip/core/rcu 0/9] rcu: v3 add lockdep-based diagnostics to rcu_dereference() Paul E. McKenney
2010-01-15 1:02 ` [PATCH tip/core/rcu 1/9] rcu: introduce lockdep-based checking to RCU read-side primitives Paul E. McKenney
2010-01-15 1:02 ` Paul E. McKenney [this message]
2010-01-15 1:02 ` [PATCH tip/core/rcu 3/9] rcu: disable lockdep checking in RCU list-traversal primitives Paul E. McKenney
2010-01-15 1:02 ` [PATCH tip/core/rcu 4/9] net: add checking to rcu_dereference() primitives Paul E. McKenney
2010-01-15 1:02 ` [PATCH tip/core/rcu 5/9] sched: use lockdep-based checking on rcu_dereference() Paul E. McKenney
2010-01-15 1:02 ` [PATCH tip/core/rcu 6/9] vfs: apply lockdep-based checking to rcu_dereference() uses Paul E. McKenney
2010-01-15 1:02 ` [PATCH tip/core/rcu 7/9] radix-tree: disable RCU lockdep checking in radix tree Paul E. McKenney
2010-01-15 1:02 ` [PATCH tip/core/rcu 8/9] idr: apply lockdep-based diagnostics to rcu_dereference() uses Paul E. McKenney
2010-01-18 23:36 ` Josh Triplett
2010-01-19 0:56 ` Paul E. McKenney
2010-01-15 1:02 ` [PATCH tip/core/rcu 9/9] rcu: documentation update for CONFIG_PROVE_RCU Paul E. McKenney
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