Messages in this thread |  | | Subject | Re: 2.6.17-rc6-mm1/pktcdvd - BUG: possible circular locking | From | Arjan van de Ven <> | Date | Wed, 21 Jun 2006 12:21:15 +0200 |
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On Mon, 2006-06-12 at 18:41 +0200, Jens Axboe wrote: > On Mon, Jun 12 2006, Arjan van de Ven wrote: > > Laurent Riffard wrote: > > >Hello, > > > > > >This BUG happened while pktcdvd service was starting. > > >Basically, the 2 following commands were issued: > > >- modprobe ptkcdvd > > >- pktsetup dvd /dev/dvd > > > > This appears to be a real bug: > > > > A normal pkt dvd block dev open takes the > > bdev_mutex in the regular block device open path, which takes > > ctl_mutex in the pkt_open function which gets called then from > > the block layer. > > > > HOWEVER the IOCTL path does it the other way around: > > > > mutex_lock(&ctl_mutex); > > ret = pkt_setup_dev(&ctrl_cmd); > > mutex_unlock(&ctl_mutex); > > > > where pkt_setup_dev in term calls pkt_new_dev which > > calls blkdev_get(), which takes the bdev_mutex. > > > > Looks very much like a AB-BA deadlock to me... > > I'd say you are right, however I haven't touched that code since 2.5 I > think - CC'ing Peter for a fix!
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