On 2016-04-06 09:38 AM, James Bottomley wrote: > On Wed, 2016-04-06 at 09:21 -0400, Bastien Philbert wrote: >> >> On 2016-04-06 03:48 AM, Julian Calaby wrote: >>> Hi Bastien, >>> >>> On Wed, Apr 6, 2016 at 7:19 AM, Bastien Philbert >>> <bastienphilbert@xxxxxxxxx> wrote: >>>> This fixes backwards locking in the function __csio_unreg_rnode >>>> to >>>> properly lock before the call to the function csio_unreg_rnode >>>> and >>>> not unlock with spin_unlock_irq as this would not allow the >>>> proper >>>> protection for concurrent access on the shared csio_hw structure >>>> pointer hw. In addition switch the locking after the critical >>>> region >>>> function call to properly unlock instead with spin_unlock_irq on >>>> >>>> Signed-off-by: Bastien Philbert <bastienphilbert@xxxxxxxxx> >>>> --- >>>> drivers/scsi/csiostor/csio_rnode.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/scsi/csiostor/csio_rnode.c >>>> b/drivers/scsi/csiostor/csio_rnode.c >>>> index e9c3b04..029a09e 100644 >>>> --- a/drivers/scsi/csiostor/csio_rnode.c >>>> +++ b/drivers/scsi/csiostor/csio_rnode.c >>>> @@ -580,9 +580,9 @@ __csio_unreg_rnode(struct csio_rnode *rn) >>>> ln->last_scan_ntgts--; >>>> } >>>> >>>> - spin_unlock_irq(&hw->lock); >>>> - csio_unreg_rnode(rn); >>>> spin_lock_irq(&hw->lock); >>>> + csio_unreg_rnode(rn); >>>> + spin_unlock_irq(&hw->lock); >>> >>> Are you _certain_ this is correct? This construct usually appears >>> when >>> a function has a particular lock held, then needs to unlock it to >>> call >>> some other function. Are you _certain_ that this isn't the case? >>> >>> Thanks, >>> >> Yes I am pretty certain this is correct. I checked the paths that >> called this function >> and it was weired that none of them gradded the spinlock before hand. > > That's not good enough. If your theory is correct, lockdep should be > dropping an already unlocked assertion in this codepath ... do you see > this? > > James > > Yes I do. For now just drop the patch but I am still concerned that we are double unlocking here. Bastien > > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
