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sched: Teach might_sleep() about preemptible RCU

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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>
This commit is contained in:
Frederic Weisbecker
2009-12-16 20:21:05 +01:00
committed by Ingo Molnar
parent 416eb39556
commit 234da7bcdc
3 changed files with 17 additions and 1 deletions
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5
include/linux/rcutiny.h
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@@ -101,4 +101,9 @@ static inline void exit_rcu(void)
{
}
static inline int rcu_preempt_depth(void)
{
return 0;
}
#endif /* __LINUX_RCUTINY_H */