Re: [PATCH 2/2] sysfs: fix race condition around sd->s_dentry, take#2

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Sat, Jun 09, 2007 at 03:49:46PM +0900, Tejun Heo wrote:
> Tejun Heo wrote:
> > Tejun Heo wrote:
> >> Greg KH wrote:
> >>> On Mon, May 21, 2007 at 10:31:01AM +0530, Maneesh Soni wrote:
> >>>> On Thu, May 17, 2007 at 08:16:10PM +0200, Tejun Heo wrote:
> >>>>> Allowing attribute and symlink dentries to be reclaimed means
> >>>>> sd->s_dentry can change dynamically.  However, updates to the field
> >>>>> are unsynchronized leading to race conditions.  This patch adds
> >>>>> sysfs_lock and use it to synchronize updates to sd->s_dentry.
> >>>>>
> >>>>> Due to the locking around ->d_iput, the check in sysfs_drop_dentry()
> >>>>> is complex.  sysfs_lock only protect sd->s_dentry pointer itself.  The
> >>>>> validity of the dentry is protected by dcache_lock, so whether dentry
> >>>>> is alive or not can only be tested while holding both locks.
> >>>>>
> >>>>> This is minimal backport of sysfs_drop_dentry() rewrite in devel
> >>>>> branch.
> >>>>>
> >>>>> DONT APPLY JUST YET
> >>>> Looks ok to me.. I have tested it it but unfortunately I couldn't
> >>>> recreate the race without the patch also. It would be helpful if
> >>>> people actually seeing the race, provide the test results.
> >>>>
> >>>> Greg, please merge this one once we have some test results.
> >>> Can someone just resend it after those test results are in, with the
> >>> proper signed-off-by, so I know it's safe to apply?
> >> I'll resend with S-O-B after someone verifies it fixes the problem.
> > 
> > Have been trying to reproduce the problem on the latest -rc but haven't
> > succeeded yet.  It seems I lost my magic recipe for these races.  Did
> > anyone succeed?
> 
> Alright, overnight test finally hit the race condition.  It takes me
> much longer now but the race condition is definitely still there.  I'll
> verify each proposed patch and send it for 2.6.22 inclusion and if
> they're accepted to -stable.

Ok, thanks for doing this.

greg k-h
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux