lkml.org 
[lkml]   [2015]   [Jul]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:sched/core] sched/fair: Test list head instead of list entry in throttle_cfs_rq()
Commit-ID:  d49db342f0e276b354383b3281c5668b6b80f5c2
Gitweb: http://git.kernel.org/tip/d49db342f0e276b354383b3281c5668b6b80f5c2
Author: Cong Wang <xiyou.wangcong@gmail.com>
AuthorDate: Wed, 24 Jun 2015 12:41:47 -0700
Committer: Ingo Molnar <mingo@kernel.org>
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 <xiyou.wangcong@gmail.com>
Signed-off-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435174907-432-1-git-send-email-xiyou.wangcong@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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

\
 
 \ /
  Last update: 2015-07-06 18:01    [W:0.795 / U:0.312 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site