On Wed, 2007-04-11 at 14:13 -0400, Jeff Mahoney wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Ian Kent wrote: > > On Thu, 2007-04-12 at 02:00 +0800, Ian Kent wrote: > >> On Thu, 2007-04-12 at 01:49 +0800, Ian Kent wrote: > >>> On Wed, 2007-04-11 at 11:05 -0400, Jeff Mahoney wrote: > >>>> Commit f50b6f8691cae2e0064c499dd3ef3f31142987f0 introduced a > >>>> race in autofs4 between autofs_lookup_unhashed() and > >>>> autofs_dentry_release(). > >>>> > >>>> autofs_dentry_release() ends up clearing the ->dentry and ->inode > >>>> members of autofs_info before removing it from the rehash list. The > >>>> list is protected by the rehash lock in both functions, but > >>>> since autofs_dentry_release() starts tearing the autofs_info struct > >>>> down before removing it from the list, autofs_lookup_unhashed() can > >>>> get a autofs_info with a NULL dentry. > >>>> > >>>> This patch moves the clearing of ->dentry and ->inode after the removal > >>>> from the rehash list. > >>> Oh .. excellent, I had a bug report but I just couldn't see it for > >>> looking. > >> Maybe I've been a bit hasty with the celebration. > >> It looks like I've got a bigger locking problem here. > >> If autofs4_dentry_release waits on the rehash lock and > >> autofs4_lookup_unhashed reclaims it then the info struct and the dentry > >> go away unconditionally as the release is called just prior to freeing > >> the dentry memory, right?. > > > > No I'm wrong, dentry_iput holds the dcache locks till it sets d_inode to > > NULL, the point of the d_inode check in autofs4_lookup_unhashed. > > > > My day is still made. > > > > Ok, that was quick. I thought it was ok, but was about to dig back in to > make sure. :)
Ya .. I'll think about it some more but it looks good. Thanks again. > > - -Jeff > > - -- > Jeff Mahoney > SUSE Labs > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.5 (GNU/Linux) > Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org > > iD8DBQFGHSVMLPWxlyuTD7IRArOcAKCGwXJaqObc3ee3W810zv5CU2h/MgCfbLUd > 4dR++d9OFimkdWGYcmJvWlE= > =+Tlm > -----END PGP SIGNATURE----- - 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/
