From: Frederic Weisbecker Date: Wed, 4 Jan 2012 19:44:57 +0000 (-0800) Subject: rcu: Improve synchronize_rcu() diagnostics X-Git-Tag: accepted/tizen/common/20141203.182822~5118^2^2~46 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=18fec7d8758dd416904da205375e6fa667defc80;p=platform%2Fkernel%2Flinux-arm64.git rcu: Improve synchronize_rcu() diagnostics Although TREE_PREEMPT_RCU indirectly uses might_sleep() to detect illegal use of synchronize_sched() and synchronize_rcu_bh() from within an RCU read-side critical section, this might_sleep() check is bypassed when there is only a single CPU (for example, when running an SMP kernel on a single-CPU system). This patch therefore adds a might_sleep() call to the rcu_blocking_is_gp() check that is unconditionally invoked from both synchronize_sched() and synchronize_rcu_bh(). Signed-off-by: Frederic Weisbecker Signed-off-by: Paul E. McKenney --- diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 6745846..73e7195 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -83,6 +83,7 @@ extern void rcu_sched_force_quiescent_state(void); /* A context switch is a grace period for RCU-sched and RCU-bh. */ static inline int rcu_blocking_is_gp(void) { + might_sleep(); /* Check for RCU read-side critical section. */ return num_online_cpus() == 1; }