Re: [PATCH] 2.6.0 NBD driver: remove send/recieve race for request

[Paul Clements]

Jens Axboe wrote:
> 
> On Fri, Aug 08 2003, Lou Langholtz wrote:
> > >@@ -499,12 +508,14 @@ static void do_nbd_request(request_queue
> > >                                     lo->disk->disk_name);
> > >                     spin_lock(&lo->queue_lock);
> > >                     list_del_init(&req->queuelist);
> > >+                    req->ref_count--;
> > >                     spin_unlock(&lo->queue_lock);
> > >                     nbd_end_request(req);
> > >                     spin_lock_irq(q->queue_lock);
> > >                     continue;
> > >             }
> > >
> > >+            req->ref_count--;
> > >             spin_lock_irq(q->queue_lock);
> > >
> > Since ref_count isn't atomic, shouldn't ref_count only be changed while
> > the queue_lock is held???
> 
> Indeed, needs to be done after regrabbing the lock.

But req is pulled off of nbd's main request queue at this point, so I
don't think anyone else could be touching it, could they?

--
Paul
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