Commit-ID: 18fec7d8758dd416904da205375e6fa667defc80
Gitweb: http://git.kernel.org/tip/18fec7d8758dd416904da205375e6fa667defc80
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Wed, 4 Jan 2012 11:44:57 -0800
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue, 21 Feb 2012 09:03:22 -0800
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@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/rcutree.h | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
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;
}
--
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