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Subject[tip: perf/urgent] perf/core: Add SRCU annotation for pmus list walk
The following commit has been merged into the perf/urgent branch of tip:

Commit-ID: 9f0bff1180efc9ea988fed3fd93da7647151ac8b
Gitweb: https://git.kernel.org/tip/9f0bff1180efc9ea988fed3fd93da7647151ac8b
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Tue, 19 Nov 2019 13:14:29 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 17 Dec 2019 13:32:46 +01:00

perf/core: Add SRCU annotation for pmus list walk

Since commit
28875945ba98d ("rcu: Add support for consolidated-RCU reader checking")

there is an additional check to ensure that a RCU related lock is held
while the RCU list is iterated.
This section holds the SRCU reader lock instead.

Add annotation to list_for_each_entry_rcu() that pmus_srcu must be
acquired during the list traversal.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Link: https://lkml.kernel.org/r/20191119121429.zhcubzdhm672zasg@linutronix.de
---
kernel/events/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4ff86d5..a1f8bde 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10523,7 +10523,7 @@ again:
goto unlock;
}

- list_for_each_entry_rcu(pmu, &pmus, entry) {
+ list_for_each_entry_rcu(pmu, &pmus, entry, lockdep_is_held(&pmus_srcu)) {
ret = perf_try_init_event(pmu, event);
if (!ret)
goto unlock;
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