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author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2012-09-01 16:28:19 (GMT) |
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committer | Tejun Heo <tj@kernel.org> | 2012-09-05 00:04:45 (GMT) |
commit | 96e65306b81351b656835c15931d1d237b252f27 (patch) | |
tree | af06187bebae44b48ca8e68a639a4ddc6b0a3509 /kernel/configs.c | |
parent | 0d7614f09c1ebdbaa1599a5aba7593f147bf96ee (diff) | |
download | linux-96e65306b81351b656835c15931d1d237b252f27.tar.xz |
workqueue: UNBOUND -> REBIND morphing in rebind_workers() should be atomic
The compiler may compile the following code into TWO write/modify
instructions.
worker->flags &= ~WORKER_UNBOUND;
worker->flags |= WORKER_REBIND;
so the other CPU may temporarily see worker->flags which doesn't have
either WORKER_UNBOUND or WORKER_REBIND set and perform local wakeup
prematurely.
Fix it by using single explicit assignment via ACCESS_ONCE().
Because idle workers have another WORKER_NOT_RUNNING flag, this bug
doesn't exist for them; however, update it to use the same pattern for
consistency.
tj: Applied the change to idle workers too and updated comments and
patch description a bit.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
Diffstat (limited to 'kernel/configs.c')
0 files changed, 0 insertions, 0 deletions