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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-02-22 20:04:46 -0500
committerIngo Molnar <mingo@elte.hu>2010-02-25 03:41:00 -0500
commitc26d34a5858f96a564c45048bf5f09319d2abad1 (patch)
tree644941c0005b8ecda4f5af3fd9f9c385f911f146
parent632ee200130899252508c478ad0e808222573fbc (diff)
rcu: Add lockdep-enabled variants of rcu_dereference()
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(). Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1266887105-1528-2-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/linux/rcupdate.h41
-rw-r--r--include/linux/srcu.h8
2 files changed, 42 insertions, 7 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index e3d37efe2703..839d296a7ac0 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -184,12 +184,12 @@ static inline int rcu_read_lock_sched_held(void)
184 ({ \ 184 ({ \
185 if (debug_locks) \ 185 if (debug_locks) \
186 WARN_ON_ONCE(!(c)); \ 186 WARN_ON_ONCE(!(c)); \
187 rcu_dereference(p); \ 187 rcu_dereference_raw(p); \
188 }) 188 })
189 189
190#else /* #ifdef CONFIG_PROVE_RCU */ 190#else /* #ifdef CONFIG_PROVE_RCU */
191 191
192#define rcu_dereference_check(p, c) rcu_dereference(p) 192#define rcu_dereference_check(p, c) rcu_dereference_raw(p)
193 193
194#endif /* #else #ifdef CONFIG_PROVE_RCU */ 194#endif /* #else #ifdef CONFIG_PROVE_RCU */
195 195
@@ -325,22 +325,49 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
325 325
326 326
327/** 327/**
328 * rcu_dereference - fetch an RCU-protected pointer in an 328 * rcu_dereference_raw - fetch an RCU-protected pointer
329 * RCU read-side critical section. This pointer may later 329 *
330 * be safely dereferenced. 330 * The caller must be within some flavor of RCU read-side critical
331 * section, or must be otherwise preventing the pointer from changing,
332 * for example, by holding an appropriate lock. This pointer may later
333 * be safely dereferenced. It is the caller's responsibility to have
334 * done the right thing, as this primitive does no checking of any kind.
331 * 335 *
332 * Inserts memory barriers on architectures that require them 336 * Inserts memory barriers on architectures that require them
333 * (currently only the Alpha), and, more importantly, documents 337 * (currently only the Alpha), and, more importantly, documents
334 * exactly which pointers are protected by RCU. 338 * exactly which pointers are protected by RCU.
335 */ 339 */
336 340#define rcu_dereference_raw(p) ({ \
337#define rcu_dereference(p) ({ \
338 typeof(p) _________p1 = ACCESS_ONCE(p); \ 341 typeof(p) _________p1 = ACCESS_ONCE(p); \
339 smp_read_barrier_depends(); \ 342 smp_read_barrier_depends(); \
340 (_________p1); \ 343 (_________p1); \
341 }) 344 })
342 345
343/** 346/**
347 * rcu_dereference - fetch an RCU-protected pointer, checking for RCU
348 *
349 * Makes rcu_dereference_check() do the dirty work.
350 */
351#define rcu_dereference(p) \
352 rcu_dereference_check(p, rcu_read_lock_held())
353
354/**
355 * rcu_dereference_bh - fetch an RCU-protected pointer, checking for RCU-bh
356 *
357 * Makes rcu_dereference_check() do the dirty work.
358 */
359#define rcu_dereference_bh(p) \
360 rcu_dereference_check(p, rcu_read_lock_bh_held())
361
362/**
363 * rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched
364 *
365 * Makes rcu_dereference_check() do the dirty work.
366 */
367#define rcu_dereference_sched(p) \
368 rcu_dereference_check(p, rcu_read_lock_sched_held())
369
370/**
344 * rcu_assign_pointer - assign (publicize) a pointer to a newly 371 * rcu_assign_pointer - assign (publicize) a pointer to a newly
345 * initialized structure that will be dereferenced by RCU read-side 372 * initialized structure that will be dereferenced by RCU read-side
346 * critical sections. Returns the value assigned. 373 * critical sections. Returns the value assigned.
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index adbe1670b366..3084f80909cd 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)
106#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ 106#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
107 107
108/** 108/**
109 * srcu_dereference - fetch SRCU-protected pointer with checking
110 *
111 * Makes rcu_dereference_check() do the dirty work.
112 */
113#define srcu_dereference(p, sp) \
114 rcu_dereference_check(p, srcu_read_lock_held(sp))
115
116/**
109 * srcu_read_lock - register a new reader for an SRCU-protected structure. 117 * srcu_read_lock - register a new reader for an SRCU-protected structure.
110 * @sp: srcu_struct in which to register the new reader. 118 * @sp: srcu_struct in which to register the new reader.
111 * 119 *