From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [Fwd: [PATCH]: Fix crash in virtio_blk during modprobe ; rmmod ; modprobe] Date: Thu, 22 May 2008 14:07:01 +0200 Message-ID: <20080522120700.GF7712@kernel.dk> References: <48341FC7.4060600@redhat.com> <200805222133.01686.rusty@rustcorp.com.au> <20080522113517.GC7712@kernel.dk> <483560FB.4040500@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Rusty Russell , virtualization@lists.linux-foundation.org, kvm@vger.kernel.org To: Chris Lalancette Return-path: Received: from brick.kernel.dk ([87.55.233.238]:21027 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759314AbYEVMHD (ORCPT ); Thu, 22 May 2008 08:07:03 -0400 Content-Disposition: inline In-Reply-To: <483560FB.4040500@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, May 22 2008, Chris Lalancette wrote: > Jens Axboe wrote: > > On Thu, May 22 2008, Rusty Russell wrote: > >> On Wednesday 21 May 2008 23:12:39 Chris Lalancette wrote: > >>> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > >>> index 4962e62..c678ac5 100644 > >>> --- a/drivers/block/virtio_blk.c > >>> +++ b/drivers/block/virtio_blk.c > >>> @@ -294,6 +294,7 @@ static void virtblk_remove(struct virtio_device *vdev) > >>> vdev->config->reset(vdev); > >>> > >>> blk_cleanup_queue(vblk->disk->queue); > >>> + del_gendisk(vblk->disk); > >>> put_disk(vblk->disk); > >>> unregister_blkdev(major, "virtblk"); > >>> mempool_destroy(vblk->pool); > >> Thanks Chris, it seems reasonable and I'm sure it works (kinda hard to > >> test here, it's my root block dev). Other drivers seem to do > >> blk_cleanup_queue() *after* del_gendisk: does it matter? > >> > >> Jens CC'd: he's gentle with my dumb questions... Rusty. > > > > del_gendisk() can generate IO, so it would seem safer to do that > > _before_ putting the queue reference :-) > > > > Ah, good to know. Out of curiousity, why would del_gendisk() generate > additional I/O? It does invalidate+sync. -- Jens Axboe