Commit-ID: 3bc97a782cc8c112f64a25143452b06206364cc8
Gitweb: http://git.kernel.org/tip/3bc97a782cc8c112f64a25143452b06206364cc8
Author: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
AuthorDate: Thu, 29 Nov 2012 16:46:05 +0800
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 7 Feb 2013 15:10:39 -0800
srcu: Remove checks preventing offline CPUs from calling srcu_read_lock()
SRCU has its own statemachine and no longer relies on normal RCU.
Its read-side critical section can now be used by an offline CPU, so this
commit removes the check and the comments, reverting the SRCU portion
of c0d6d01b (rcu: Check for illegal use of RCU from offlined CPUs).
It also makes the code match the comments in whatisRCU.txt:
g. Do you need read-side critical sections that are respected
even though they are in the middle of the idle loop, during
user-mode execution, or on an offlined CPU? If so, SRCU is the
only choice that will work for you.
[ paulmck: There is at least one remaining issue, namely use of lockdep
with tracing enabled. ]
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/srcu.h | 5 -----
1 file changed, 5 deletions(-)
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 6eb691b..ae3ee39 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -163,9 +163,6 @@ void srcu_barrier(struct srcu_struct *sp);
* power mode. This way we can notice an extended quiescent state to
* other CPUs that started a grace period. Otherwise we would delay any
* grace period as long as we run in the idle task.
- *
- * Similarly, we avoid claiming an SRCU read lock held if the current
- * CPU is offline.
*/
static inline int srcu_read_lock_held(struct srcu_struct *sp)
{
@@ -173,8 +170,6 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp)
return 1;
if (rcu_is_cpu_idle())
return 0;
- if (!rcu_lockdep_current_cpu_online())
- return 0;
return lock_is_held(&sp->dep_map);
}
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|