[tip: perf/urgent] perf/core: Add SRCU annotation for pmus list walk

[tip-bot2 for Sebastian Andrzej Siewior]

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@xxxxxxxxxxxxx>
AuthorDate:    Tue, 19 Nov 2019 13:14:29 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20191119121429.zhcubzdhm672zasg@xxxxxxxxxxxxx
---
 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;