On Wed, 24 Jul 2002, Jens Axboe wrote:
> On Wed, Jul 24 2002, Bartlomiej Zolnierkiewicz wrote:
> > > void blk_start_queue(request_queue_t *q)
> > > {
> > > if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) {
> > > unsigned long flags;
> > >
> > > ================== possigle race here for qeue_flags BTW.
> > >
> > > spin_lock_irqsave(q->queue_lock, flags);
> > > clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags);
> > >
> > > if (!elv_queue_empty(q))
> > > q->request_fn(q);
> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > If we call it from within request_fn then if this isn't recursion on the
> > > kernel stack then I don't know...
> >
> > You really don't know.
> >
> > And funny thing is I have diffirent blk_start_queue() function in my tree
> > (2.5.27) ? Without described above race and without possibilty of
> > recursion...
> >
> > 2.5.27:drivers/block/ll_rw_blk.c
> > void blk_start_queue(request_queue_t *q)
> > {
> > if (test_and_clear_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) {
> > unsigned long flags;
> >
> > spin_lock_irqsave(q->queue_lock, flags);
> > if (!elv_queue_empty(q))
> > q->request_fn(q);
> > spin_unlock_irqrestore(q->queue_lock, flags);
> > }
> > }
>
> Yep, the version Martin posted must be really old.
It's worst. Martin's version exists only in his tree (mind?).
I checked back revision and blk_start_queue() was inroduced in 2.5.19
and it was the correct one.
> --
> Jens Axboe
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This archive was generated by hypermail 2b29 : Tue Jul 30 2002 - 14:00:15 EST