diff options
| author | Lai Jiangshan <laijs@cn.fujitsu.com> | 2012-09-02 00:28:19 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-09-19 15:04:58 +0100 |
| commit | f152c392a7715862818fb671cbd5e0b2545aedae (patch) | |
| tree | 2b70726d6ba9730d54dab7a1efe35ce1d5a56ab0 /Documentation/early-userspace | |
| parent | e8bf333a7a14bd2fa1d091794a168d3ed570457d (diff) | |
workqueue: UNBOUND -> REBIND morphing in rebind_workers() should be atomic
commit 96e65306b81351b656835c15931d1d237b252f27 upstream.
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.
stable: Idle worker rebinding doesn't apply for -stable and
WORKER_UNBOUND used to be WORKER_ROGUE. Updated accordingly.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'Documentation/early-userspace')
0 files changed, 0 insertions, 0 deletions