Re: [PATCH] vfs: fix race in rcu lookup of pruned dentry
[Posted July 19, 2011 by corbet]
| From: |
| Hugh Dickins <hughd-AT-google.com> |
| To: |
| Al Viro <viro-AT-zeniv.linux.org.uk> |
| Subject: |
| Re: [PATCH] vfs: fix race in rcu lookup of pruned dentry |
| Date: |
| Mon, 18 Jul 2011 19:07:54 -0700 (PDT) |
| Message-ID: |
| <alpine.LSU.2.00.1107181903350.23830@sister.anvils> |
| Cc: |
| Linus Torvalds <torvalds-AT-linux-foundation.org>,
Andrew Morton <akpm-AT-linux-foundation.org>,
Nick Piggin <npiggin-AT-kernel.dk>, linux-kernel-AT-vger.kernel.org,
linux-fsdevel-AT-vger.kernel.org |
| Archive‑link: | |
Article |
On Tue, 19 Jul 2011, Al Viro wrote:
> On Mon, Jul 18, 2011 at 04:27:53PM -0700, Linus Torvalds wrote:
> > On Mon, Jul 18, 2011 at 4:21 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> > >
> > > Linus, are you OK with me slapping your s-o-b on it?
> >
> > Yup.
> >
> > And it feels so right that I think we should just do it for 3.0.
It looked sane, but in fact was insane. Enough testing for now,
I say it's good to go, if you fold in this small adjustment...
[PATCH] fix sense of __read_seqcount_retry test
Hah, good thing I hacked something in to check we're going the quick
way: __read_seqcount_retry() returns *true* when a retry is needed.
Signed-off-by: Hugh Dickins <hughd@google.com>
---
fs/namei.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 3.0-git+/fs/namei.c 2011-07-18 18:31:36.273731128 -0700
+++ linux/fs/namei.c 2011-07-18 18:32:35.158022444 -0700
@@ -960,7 +960,7 @@ static bool __follow_mount_rcu(struct na
* so we can use __read_seqcount_retry() to check the prev
* sequence numbers.
*/
- if (!__read_seqcount_retry(&path->dentry->d_seq, nd->seq))
+ if (__read_seqcount_retry(&path->dentry->d_seq, nd->seq))
return false;
path->mnt = mounted;
path->dentry = mounted->mnt_root;
--
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