diff options
| author | Frederic Weisbecker <fweisbec@gmail.com> | 2009-12-16 20:21:05 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-12-17 09:46:44 +0100 |
| commit | 234da7bcdc7aaa935846534c3b726dbc79a9cdd5 (patch) | |
| tree | a391afd465d6493a9f1bb274c225bab4d303aad0 | |
| parent | 416eb39556a03d1c7e52b0791e9052ccd71db241 (diff) | |
sched: Teach might_sleep() about preemptible RCU
In practice, it is harmless to voluntarily sleep in a
rcu_read_lock() section if we are running under preempt rcu, but
it is illegal if we build a kernel running non-preemptable rcu.
Currently, might_sleep() doesn't notice sleepable operations
under rcu_read_lock() sections if we are running under
preemptable rcu because preempt_count() is left untouched after
rcu_read_lock() in this case. But we want developers who test
their changes under such config to notice the "sleeping while
atomic" issues.
So we add rcu_read_lock_nesting to prempt_count() in
might_sleep() checks.
[ v2: Handle rcu-tiny ]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1260991265-8451-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | include/linux/rcutiny.h | 5 | ||||
| -rw-r--r-- | include/linux/rcutree.h | 11 | ||||
| -rw-r--r-- | kernel/sched.c | 2 |
3 files changed, 17 insertions, 1 deletions
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index c4ba9a78721e..96cc307ed9f4 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -101,4 +101,9 @@ static inline void exit_rcu(void) { } +static inline int rcu_preempt_depth(void) +{ + return 0; +} + #endif /* __LINUX_RCUTINY_H */ diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index c93eee5911b0..8044b1b94333 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -45,6 +45,12 @@ extern void __rcu_read_unlock(void); extern void synchronize_rcu(void); extern void exit_rcu(void); +/* + * Defined as macro as it is a very low level header + * included from areas that don't even know about current + */ +#define rcu_preempt_depth() (current->rcu_read_lock_nesting) + #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ static inline void __rcu_read_lock(void) @@ -63,6 +69,11 @@ static inline void exit_rcu(void) { } +static inline int rcu_preempt_depth(void) +{ + return 0; +} + #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ static inline void __rcu_read_lock_bh(void) diff --git a/kernel/sched.c b/kernel/sched.c index af7dfa74e6bb..7be88a7be047 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -9682,7 +9682,7 @@ void __init sched_init(void) #ifdef CONFIG_DEBUG_SPINLOCK_SLEEP static inline int preempt_count_equals(int preempt_offset) { - int nested = preempt_count() & ~PREEMPT_ACTIVE; + int nested = (preempt_count() & ~PREEMPT_ACTIVE) + rcu_preempt_depth(); return (nested == PREEMPT_INATOMIC_BASE + preempt_offset); } |