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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 <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: <1267667418-32233-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul E. McKenney 2010-03-03 17:50:16 -08:00 committed by Ingo Molnar
parent cc5b83a9f8
commit e6033e3b30
1 changed files with 14 additions and 0 deletions
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14
include/linux/rcupdate.h
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@ -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 */