sched: Teach might_sleep() about preemptible RCU
authorFrederic Weisbecker <fweisbec@gmail.com>
Wed, 16 Dec 2009 19:21:05 +0000 (20:21 +0100)
committerIngo Molnar <mingo@elte.hu>
Thu, 17 Dec 2009 08:46:44 +0000 (09:46 +0100)
commit234da7bcdc7aaa935846534c3b726dbc79a9cdd5
treea391afd465d6493a9f1bb274c225bab4d303aad0
parent416eb39556a03d1c7e52b0791e9052ccd71db241
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>
include/linux/rcutiny.h
include/linux/rcutree.h
kernel/sched.c