On Sun, 2016-04-24 at 17:13 -0400, valdis.kletni...@vt.edu wrote:
> On Sun, 24 Apr 2016 14:00:17 -0700, Eric Dumazet said:
> > On Sun, 2016-04-24 at 15:56 -0400, valdis.kletni...@vt.edu wrote:
> > > On Sun, 24 Apr 2016 12:46:42 -0700, Eric Dumazet said:
> > >
> > > > >>> + return !debug_locks ||
> > > > >>> + lockdep_is_held(&sk->sk_lock) ||
> > >
> > > > Issue here is that once lockdep detected a problem (not necessarily in
> > > > net/ tree btw), your helper always 'detect' a problem, since lockdep
> > > > automatically disables itself.
> > >
> > > "D'Oh!" -- H. Simpson
> > >
> > > I thought this patch looked suspect, but couldn't put my finger on it. The
> > > reason why I got like 41,000 of them is because I built a kernel that has
> > > lockdep enabled, but I have an out-of-tree module that doesn't init
> > > something,
> > > so I get this:
> > >
> > > [ 48.898156] INFO: trying to register non-static key.
> > > [ 48.898157] the code is fine but needs lockdep annotation.
> > > [ 48.898157] turning off the locking correctness validator.
> > >
> > > After which point, even with this patch, every time through it's still
> > > going to
> > > explode.
> >
> > Which patch are you talking about ?
>
> The one that adds the !debug_locks check - once my out-of-kernel module
> hits something that turns off lockdep, it's *still* going to complain on
> pretty much all the same packets it complained about earlier. I thought
> it looked suspicious, but you clarified why...
It does not make sense to me. If lockdep is disabled, then debug_locks
is 0.
So no complain should happen from networking.
I was about to send following patch, please check it solves the issue. ?
(It certainly did for me, once I forced a lockdep splat loading a buggy
module)
Thanks
From: Eric Dumazet <eduma...@google.com>
Valdis reported tons of stack dumps caused by WARN_ON() in sock_owned_by_user()
This test needs to be relaxed if/when lockdep disables itself.
Note that other lockdep_sock_is_held() callers are all from
rcu_dereference_protected() sections which already are disabled
if/when lockdep has been disabled.
Fixes: fafc4e1ea1a4 ("sock: tigthen lockdep checks for sock_owned_by_user")
Reported-by: Valdis Kletnieks <valdis.kletni...@vt.edu>
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
include/net/sock.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/sock.h b/include/net/sock.h
index 52448baf19d7..f492d01512ed 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1409,7 +1409,7 @@ static inline void unlock_sock_fast(struct sock *sk, bool
slow)
static inline bool sock_owned_by_user(const struct sock *sk)
{
#ifdef CONFIG_LOCKDEP
- WARN_ON(!lockdep_sock_is_held(sk));
+ WARN_ON_ONCE(!lockdep_sock_is_held(sk) && !debug_locks);
#endif
return sk->sk_lock.owned;
}
