From: Paul E. McKenney Date: Thu, 4 Mar 2010 01:50:16 +0000 (-0800) Subject: rcu: Make rcu_read_lock_sched_held() handle !PREEMPT X-Git-Tag: v2.6.34-rc2~51^2~7 X-Git-Url: https://bbs.cooldavid.org/git/?a=commitdiff_plain;h=e6033e3b307fcfae08408e0673266db38392bda4;p=net-next-2.6.git rcu: Make rcu_read_lock_sched_held() handle !PREEMPT The rcu_read_lock_sched_held() needs to unconditionally return the value "1" in a !PREEMPT kernel, because under !PREEMPT, -all- kernel code is implicitly preempt-disabled. This patch makes this happen. 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: <1267667418-32233-1-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar --- diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index c8437362633..e22960ecb71 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -136,6 +136,7 @@ static inline int rcu_read_lock_bh_held(void) * can prove otherwise. Note that disabling of preemption (including * disabling irqs) counts as an RCU-sched read-side critical section. */ +#ifdef CONFIG_PREEMPT static inline int rcu_read_lock_sched_held(void) { int lockdep_opinion = 0; @@ -144,6 +145,12 @@ static inline int rcu_read_lock_sched_held(void) lockdep_opinion = lock_is_held(&rcu_sched_lock_map); return lockdep_opinion || preempt_count() != 0 || !rcu_scheduler_active; } +#else /* #ifdef CONFIG_PREEMPT */ +static inline int rcu_read_lock_sched_held(void) +{ + return 1; +} +#endif /* #else #ifdef CONFIG_PREEMPT */ #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ @@ -164,10 +171,17 @@ static inline int rcu_read_lock_bh_held(void) return 1; } +#ifdef CONFIG_PREEMPT static inline int rcu_read_lock_sched_held(void) { return preempt_count() != 0 || !rcu_scheduler_active; } +#else /* #ifdef CONFIG_PREEMPT */ +static inline int rcu_read_lock_sched_held(void) +{ + return 1; +} +#endif /* #else #ifdef CONFIG_PREEMPT */ #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */