Commit-ID:  d49db342f0e276b354383b3281c5668b6b80f5c2
Gitweb:     http://git.kernel.org/tip/d49db342f0e276b354383b3281c5668b6b80f5c2
Author:     Cong Wang <[email protected]>
AuthorDate: Wed, 24 Jun 2015 12:41:47 -0700
Committer:  Ingo Molnar <[email protected]>
CommitDate: Mon, 6 Jul 2015 14:15:08 +0200

sched/fair: Test list head instead of list entry in throttle_cfs_rq()

According to the comments, we need to test if this is
the first throttled task, however, list_empty() tests on
the entry cfs_rq->throttled_list, not the head, this is wrong.

This is a bug because we don't re-init the list entry after
removing it from the list, so list_empty() could return false
even if the list is really empty.

Signed-off-by: Cong Wang <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Ben Segall <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: 
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 65c8f3e..d113c3b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3683,7 +3683,7 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
        cfs_rq->throttled = 1;
        cfs_rq->throttled_clock = rq_clock(rq);
        raw_spin_lock(&cfs_b->lock);
-       empty = list_empty(&cfs_rq->throttled_list);
+       empty = list_empty(&cfs_b->throttled_cfs_rq);
 
        /*
         * Add to the _head_ of the list, so that an already-started
--
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