From c26d34a5858f96a564c45048bf5f09319d2abad1 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 22 Feb 2010 17:04:46 -0800 Subject: [PATCH] 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 Signed-off-by: Paul E. McKenney 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 --- 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 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) ({ \ 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 */ @@ -325,21 +325,48 @@ 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 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 @@ -105,6 +105,14 @@ 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. -- 2.20.1