Messages in this thread | | | Date | Mon, 12 Jun 2006 18:41:53 +0200 | From | Jens Axboe <> | Subject | Re: 2.6.17-rc6-mm1/pktcdvd - BUG: possible circular locking |
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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!
-- Jens Axboe
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