Commit 18fec7d8 authored Jan 04, 2012 by Frederic Weisbecker Committed by Paul E. McKenney Feb 21, 2012

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 <fweisbec@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

parent 4c62abc9

include/linux/rcutree.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}