Re: [PATCH block/for-linus] block: blk-throttle should be drained regardless of q->elevator

[Vivek Goyal <vgoyal@redhat.com>]

On Mon, Feb 13, 2012 at 03:40:57PM -0800, Tejun Heo wrote:
> Hello,
> 
> On Mon, Feb 13, 2012 at 06:27:42PM -0500, Vivek Goyal wrote:
> > > -	/*
> > > -	 * Drain all requests queued before DEAD marking.  The caller might
> > > -	 * be trying to tear down @q before its elevator is initialized, in
> > > -	 * which case we don't want to call into draining.
> > > -	 */
> > > -	if (q->elevator)
> > > -		blk_drain_queue(q, true);
> > > +	/* drain all requests queued before DEAD marking */
> > 
> > We have already marked the queue DEAD before we start draining the queue.
> > May be we need to fix the comment.
> 
> Hmmm... it actually is correct.  It drains all requests which were
> queued before the preceding DEAD marking.  ie... it's describing the
> following.
> 
> 	1. requests queued
> 	2. mark q DEAD
> 	3. drain requests which were queued before #2.  We don't care
> 	   about requests queued after #2.

Ok, thanks. I read the comment wrong. I thought of it as "drain all requests before marking queue DEAD". :-)

Thanks
Vivek