On Thu, 2018-01-11 at 12:29 -0500, Mike Snitzer wrote:
> On Thu, Jan 11 2018 at 12:18pm -0500,
> Bart Van Assche <[email protected]> wrote:
>
> > On Thu, 2018-01-11 at 12:04 -0500, Mike Snitzer wrote:
> > > So my v4, that I'll send out shortly, won't be using test_and_clear_bit()
> >
> > Please use queue_flag_set(), queue_flag_clear(),
> > queue_flag_test_and_clear() and/or
> > queue_flag_test_and_set() to manipulate queue flags.
>
> Can you please expand on this? My patch is only using test_bit().
Hello Mike,
I was referring to the following code, which apparenly is existing code:
mutex_lock(&q->sysfs_lock);
queue_flag_clear_unlocked(QUEUE_FLAG_REGISTERED, q);
mutex_unlock(&q->sysfs_lock);
The above code is wrong. Other code that changes the queue flags protects
these changes with the the queue lock. The above code should be changed into
the following:
spin_lock_irq(q->queue_lock);
queue_flag_clear(QUEUE_FLAG_REGISTERED, q);
spin_unlock_irq(q->queue_lock);
The only functions from which it is safe to call
queue_flag_(set|clear)_unlocked()
without holding the queue lock are blk_alloc_queue_node() and
__blk_release_queue() because for these functions it is guaranteed that no queue
flag changes can happen from another context, e.g. through a
blk_set_queue_dying()
call.
Bart.
