Re: please DON'T run 2.5.27 with IDE!

[Jens Axboe <axboe@suse.de>]

On Wed, Jul 24 2002, Marcin Dalecki wrote:
> >>So look at drivers which call blk_start_queue() from within
> >>q->request_fn context, which is, well, causing deliberate *recursion*.
> >>
> >
> >
> >Are you sure? If so they should first check whether queue is
> >started/stopped, if they don't it is a bug.
> 
> 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...
> 
>                 spin_unlock_irqrestore(q->queue_lock, flags);
>         }
> }

Care to enlighten us on exactly which block drivers call
blk_start_queue() from request_fn?

-- 
Jens Axboe