From: Jens Axboe <jens.axboe@xxxxxxxxxx>
Subject: Re: [PATCH] bsg: fix the deadlock on discarding done commands
Date: Thu, 7 Jun 2007 13:23:09 +0200
> On Tue, Jun 05 2007, FUJITA Tomonori wrote:
> > From: Jens Axboe <jens.axboe@xxxxxxxxxx>
> > Subject: Re: [PATCH] bsg: fix the deadlock on discarding done commands
> > Date: Mon, 4 Jun 2007 16:04:15 +0200
> >
> > > On Sun, Jun 03 2007, FUJITA Tomonori wrote:
> > > > The previous commit to fix a blocking read bug put a bug that leads a
> > > > deadlock on discarding done commands. We don't need bsg_device's lock
> > > > there.
> > > >
> > > > Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> > > > ---
> > > > block/bsg.c | 5 +----
> > > > 1 files changed, 1 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/block/bsg.c b/block/bsg.c
> > > > index 2f78d7d..9b5f6d7 100644
> > > > --- a/block/bsg.c
> > > > +++ b/block/bsg.c
> > > > @@ -466,11 +466,8 @@ static int bsg_complete_all_commands(str
> > > > */
> > > > ret = 0;
> > > > do {
> > > > - spin_lock_irq(&bd->lock);
> > > > - if (!bd->queued_cmds) {
> > > > - spin_unlock_irq(&bd->lock);
> > > > + if (!bd->queued_cmds)
> > > > break;
> > > > - }
> > > >
> > > > bc = bsg_get_done_cmd(bd);
> > > > if (IS_ERR(bc))
> > >
> > > int read should be atomic, but it probably still needs serialization.
> > > I'd be more comfortable with just adding the appropriate
> > > spin_unlock_irq() before bsg_get_done_cmd(). It's not a fast path
> > > anyway, just for device going away.
> >
> > Ok, here's a patch though only one is accessing to a bsg device here,
> > I think. Anyway, sorry about the silly bug.
>
> Thanks, applied.
>
> > BTW, any chance to push bsg to mainline? The scsi mid-layer bidi is
> > not ready, but the block layer bidi is ready with the rq->next_rq
> > patch (and I have the bsg bidi patch). Then I can ask James to push
> > the SMP pass through patches to mainline.
>
> Sure, might as well get on with it. I'll push it once 2.6.23 opens.
Cool, thanks.
I'll submit the bsg bidi patches shortly.
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