On Mon, 01 Jul 2013 15:24:11 -0700 James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote:
> > --- a/block/blk-core.c~block-fix-possible-sleep-in-invalid-context-fix
> > +++ a/block/blk-core.c
> > @@ -3159,15 +3159,14 @@ EXPORT_SYMBOL(blk_pre_runtime_resume);
> > */
> > void blk_post_runtime_resume(struct request_queue *q, int err)
> > {
> > + spin_lock_irq(q->queue_lock);
> > if (!err) {
> > - spin_lock_irq(q->queue_lock);
> > q->rpm_status = RPM_ACTIVE;
> > __blk_run_queue(q);
> > pm_runtime_mark_last_busy(q->dev);
> > spin_unlock_irq(q->queue_lock);
> > pm_request_autosuspend(q->dev);
> > } else {
> > - spin_lock_irq(q->queue_lock);
> > q->rpm_status = RPM_SUSPENDED;
> > spin_unlock_irq(q->queue_lock);
> > }
> > _
> >
> >
> > I wonder if we actually need locking around that second write to
> > q->rpm_status.
>
> Shouldn't: it's an int, which makes it a 32 bit quantity we believe to
> have atomic write properties on every platform.
Yes, but. If there's some other code path which does:
spin_lock(queue_lock);
x = q->rpm_status;
...
y = q->rpm_status;
...
<assumes x == y>
spin_unlock(queue_lock);
then it blows up if we make the suggested change. Stranger things have
happened...
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