From: David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
To: jarkao2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
Cc: johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org,
netdev-BkyiQQGWkgE@public.gmane.org,
peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org,
Larry.Finger-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org,
kaber-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org,
torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org
Subject: Re: Kernel WARNING: at net/core/dev.c:1330 __netif_schedule+0x2c/0x98()
Date: Fri, 01 Aug 2008 00:00:05 -0700 (PDT) [thread overview]
Message-ID: <20080801.000005.102314582.davem@davemloft.net> (raw)
In-Reply-To: <20080801064810.GA4435-8HppEYmqbBCE+EvaaNYduQ@public.gmane.org>
From: Jarek Poplawski <jarkao2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Date: Fri, 1 Aug 2008 06:48:10 +0000
> On Thu, Jul 31, 2008 at 05:29:32AM -0700, David Miller wrote:
> > + /* No need to grab the _xmit_lock here. If the
> > + * queue is not stopped for another reason, we
> > + * force a schedule.
> > + */
> > + clear_bit(__QUEUE_STATE_FROZEN, &txq->state);
>
> The comments in asm-x86/bitops.h to set_bit/clear_bit are rather queer
> about reordering on non x86: isn't eg. smp_mb_before_clear_bit()
> useful here?
It doesn't matter, we need no synchronization here at all.
We unconditionally perform a __netif_schedule(), and that
will run the TX queue on the local cpu. We will take the
_xmit_lock at least once time if in fact the queue was not
stopped before the first froze it.
> > diff --git a/net/core/dev.c b/net/core/dev.c
> > index 63d6bcd..69320a5 100644
> > --- a/net/core/dev.c
> > +++ b/net/core/dev.c
> > @@ -4200,6 +4200,7 @@ static void netdev_init_queues(struct net_device *dev)
> > {
> > netdev_init_one_queue(dev, &dev->rx_queue, NULL);
> > netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
> > + spin_lock_init(&dev->tx_global_lock);
>
> This will probably need some lockdep annotations similar to
> _xmit_lock.
I highly doubt it. It will never be taken nested with another
device's instance.
It is only ->hard_start_xmit() leading to another ->hard_start_xmit()
where this can currently happen, but tx_global_lock will not be used
in such paths.
> > @@ -135,7 +135,8 @@ static inline int qdisc_restart(struct Qdisc *q)
> > txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
> >
> > HARD_TX_LOCK(dev, txq, smp_processor_id());
> > - if (!netif_subqueue_stopped(dev, skb))
> > + if (!netif_tx_queue_stopped(txq) &&
> > + !netif_tx_queue_frozen(txq))
> > ret = dev_hard_start_xmit(skb, dev, txq);
> > HARD_TX_UNLOCK(dev, txq);
>
> This thing is the most doubtful to me: before this patch callers would
> wait on this lock. Now they take the lock without problems, check the
> flags, and let to take this lock again, doing some re-queing in the
> meantime.
>
> So, it seems HARD_TX_LOCK should rather do some busy looping now with
> a trylock, and re-checking the _FROZEN flag. Maybe even this should
> be done in __netif_tx_lock(). On the other hand, this shouldn't block
> too much the owner of tx_global_lock() with taking such a lock.
'ret' will be NETDEV_TX_BUSY in such a case (finding the queue
frozen), which will cause the while() loop in __qdisc_run() to
terminate.
The freezer will unconditionally schedule a new __qdisc_run()
when it unfreezes the queue.
Sure it's possible for some cpus to bang in and out of there
a few times, but that's completely harmless. And it can only
happen a few times since this freeze state is only held across
a critical section.
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next prev parent reply other threads:[~2008-08-01 7:00 UTC|newest]
Thread overview: 204+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-20 17:44 [GIT]: Networking David Miller
2008-07-20 17:59 ` Arjan van de Ven
2008-07-20 23:52 ` David Miller
2008-07-21 20:32 ` David Miller
2008-07-21 0:54 ` Linus Torvalds
2008-07-21 1:03 ` David Miller
2008-07-21 1:09 ` Alexey Dobriyan
2008-07-21 1:14 ` David Miller
2008-07-21 1:22 ` Alexey Dobriyan
2008-07-21 2:40 ` Alexey Dobriyan
2008-07-21 2:48 ` David Miller
2008-07-21 5:11 ` David Miller
2008-07-21 9:48 ` Alexander Beregalov
2008-07-21 10:16 ` Ben Hutchings
2008-07-21 15:35 ` David Miller
2008-07-21 16:04 ` Alexander Beregalov
2008-07-21 11:57 ` Alexey Dobriyan
2008-07-21 15:27 ` David Miller
2008-07-21 16:49 ` Linus Torvalds
2008-07-21 16:53 ` David Miller
2008-07-21 1:20 ` Patrick McHardy
2008-07-21 11:28 ` Stefan Richter
2008-07-21 11:45 ` James Morris
2008-07-21 12:05 ` Patrick McHardy
2008-07-21 17:28 ` David Miller
2008-07-21 17:40 ` Linus Torvalds
2008-07-21 20:33 ` Patrick McHardy
2008-07-23 23:42 ` David Miller
2008-07-21 1:07 ` Linus Torvalds
2008-07-21 1:17 ` David Miller
2008-07-21 8:36 ` iwlwifi: fix build bug in "iwlwifi: fix LED stall" Ingo Molnar
2008-07-21 10:02 ` Winkler, Tomas
2008-07-21 10:53 ` Ingo Molnar
2008-07-21 12:12 ` [PATCH] iwlwifi: RS small compile warnings without CONFIG_IWLWIFI_DEBUG Tomas Winkler
2008-07-21 12:12 ` [PATCH] iwlwifi: " Tomas Winkler
2008-07-21 12:12 ` [PATCH] iwlwifi: compilation error when CONFIG_IWLWIFI_DEBUG is not set Tomas Winkler
2008-07-21 13:30 ` [crash, bisected] Kernel BUG at ffffffff8079afb1 (__netif_schedule()) Ingo Molnar
2008-07-21 13:45 ` [crash] BUG: unable to handle kernel NULL pointer dereference at 0000000000000370 Ingo Molnar
2008-07-21 14:30 ` Ingo Molnar
2008-07-21 15:04 ` Ingo Molnar
2008-07-21 15:24 ` David Miller
2008-07-21 18:18 ` Ian Schram
2008-07-21 19:06 ` Ingo Molnar
[not found] ` <20080721190646.GA19044-X9Un+BFzKDI@public.gmane.org>
2008-07-21 19:13 ` Larry Finger
[not found] ` <4884DFEE.4060003-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org>
2008-07-21 19:34 ` Ingo Molnar
[not found] ` <20080721193425.GA29287-X9Un+BFzKDI@public.gmane.org>
2008-07-21 19:43 ` Larry Finger
[not found] ` <4884E6E6.7010800-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org>
2008-07-21 19:47 ` Linus Torvalds
2008-07-21 20:15 ` David Miller
[not found] ` <alpine.LFD.1.10.0807211246280.31863-5CScLwifNT1QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
2008-07-21 20:28 ` Larry Finger
2008-07-21 20:21 ` David Miller
[not found] ` <20080721.132100.128525904.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-21 20:38 ` Larry Finger
2008-07-21 20:46 ` David Miller
2008-07-21 20:51 ` Patrick McHardy
2008-07-21 21:01 ` David Miller
2008-07-21 21:06 ` Patrick McHardy
[not found] ` <4884FA3F.70109-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>
2008-07-21 21:35 ` Patrick McHardy
[not found] ` <48850121.9090106-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>
2008-07-21 21:42 ` Patrick McHardy
2008-07-21 21:51 ` Larry Finger
[not found] ` <488504D9.5090100-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org>
2008-07-21 22:04 ` Patrick McHardy
[not found] ` <488507FB.9050101-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>
2008-07-21 22:40 ` Larry Finger
[not found] ` <4885104A.2070201-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org>
2008-07-21 23:15 ` David Miller
2008-07-22 6:34 ` Larry Finger
[not found] ` <48857F74.2040406-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org>
2008-07-22 10:51 ` Jarek Poplawski
2008-07-22 11:32 ` David Miller
2008-07-22 12:52 ` Larry Finger
2008-07-22 20:43 ` David Miller
2008-07-22 13:02 ` Larry Finger
[not found] ` <4885DA49.50703-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org>
2008-07-22 14:53 ` Patrick McHardy
[not found] ` <4885F46A.30309-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>
2008-07-22 21:17 ` David Miller
2008-07-22 16:39 ` Kernel WARNING: at net/core/dev.c:1330 __netif_schedule+0x2c/0x98() Larry Finger
[not found] ` <48860D4B.8070003-tQ5ms3gMjBLk1uMJSBkQmQ@public.gmane.org>
2008-07-22 17:20 ` Patrick McHardy
2008-07-22 18:39 ` Larry Finger
2008-07-22 18:44 ` Patrick McHardy
[not found] ` <48862A76.8030307-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>
2008-07-22 19:30 ` Larry Finger
2008-07-22 23:04 ` David Miller
2008-07-23 6:20 ` Jarek Poplawski
2008-07-23 7:59 ` David Miller
[not found] ` <20080723.005921.113868915.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-23 8:54 ` Jarek Poplawski
[not found] ` <20080723085452.GB4561-8HppEYmqbBCE+EvaaNYduQ@public.gmane.org>
2008-07-23 9:03 ` Peter Zijlstra
2008-07-23 9:35 ` Jarek Poplawski
[not found] ` <20080723093459.GC4561-8HppEYmqbBCE+EvaaNYduQ@public.gmane.org>
2008-07-23 9:50 ` Peter Zijlstra
2008-07-23 10:13 ` Jarek Poplawski
2008-07-23 10:58 ` Peter Zijlstra
2008-07-23 11:35 ` Jarek Poplawski
[not found] ` <20080723113519.GE4561-8HppEYmqbBCE+EvaaNYduQ@public.gmane.org>
2008-07-23 11:49 ` Jarek Poplawski
2008-07-23 20:16 ` David Miller
2008-07-23 20:43 ` Jarek Poplawski
[not found] ` <20080723204335.GA14788-dUp/P3zyUuaNj9Bq2fkWzw@public.gmane.org>
2008-07-23 20:55 ` David Miller
[not found] ` <20080723.131607.79681752.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-24 9:10 ` Peter Zijlstra
2008-07-24 9:20 ` David Miller
[not found] ` <20080724.022040.23129457.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-24 9:27 ` Peter Zijlstra
2008-07-24 9:32 ` David Miller
[not found] ` <20080724.023210.229338550.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-24 10:08 ` Peter Zijlstra
2008-07-24 10:38 ` Nick Piggin
[not found] ` <200807242038.36693.nickpiggin-/E1597aS9LT0CCvOHzKKcA@public.gmane.org>
2008-07-24 10:55 ` Miklos Szeredi
[not found] ` <E1KLyUI-0006ZS-Cg-8f8m9JG5TPIdUIPVzhDTVZP2KDSNp7ea@public.gmane.org>
2008-07-24 11:06 ` Nick Piggin
[not found] ` <200807242106.52672.nickpiggin-/E1597aS9LT0CCvOHzKKcA@public.gmane.org>
2008-08-01 21:10 ` Paul E. McKenney
2008-07-24 10:59 ` Peter Zijlstra
2008-08-01 21:10 ` Paul E. McKenney
2008-07-23 20:14 ` David Miller
[not found] ` <20080723.131441.200166513.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-24 7:00 ` Peter Zijlstra
2008-07-25 17:04 ` Ingo Oeser
[not found] ` <200807251904.37302.netdev-BkyiQQGWkgE@public.gmane.org>
2008-07-25 18:36 ` Jarek Poplawski
2008-07-25 19:16 ` Johannes Berg
[not found] ` <1217013384.4758.5.camel-YfaajirXv214zXjbi5bjpg@public.gmane.org>
2008-07-25 19:34 ` Jarek Poplawski
2008-07-25 19:36 ` Johannes Berg
2008-07-25 20:01 ` Jarek Poplawski
[not found] ` <20080725200137.GC3107-dUp/P3zyUuaNj9Bq2fkWzw@public.gmane.org>
2008-07-26 9:18 ` David Miller
2008-07-26 10:53 ` Jarek Poplawski
[not found] ` <20080726.021846.236624483.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-26 13:18 ` Jarek Poplawski
[not found] ` <20080726131838.GA2873-dUp/P3zyUuaNj9Bq2fkWzw@public.gmane.org>
2008-07-27 0:34 ` David Miller
[not found] ` <20080726.173434.48036095.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-27 20:37 ` Jarek Poplawski
[not found] ` <20080727203757.GA2527-dUp/P3zyUuaNj9Bq2fkWzw@public.gmane.org>
2008-07-31 12:29 ` David Miller
[not found] ` <20080731.052932.110299354.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-07-31 12:38 ` Nick Piggin
2008-07-31 12:44 ` David Miller
2008-08-01 4:27 ` David Miller
[not found] ` <20080731.212729.138736823.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2008-08-01 7:09 ` Peter Zijlstra
2008-08-01 6:48 ` Jarek Poplawski
[not found] ` <20080801064810.GA4435-8HppEYmqbBCE+EvaaNYduQ@public.gmane.org>
2008-08-01 7:00 ` David Miller [this message]
2008-08-01 7:01 ` Jarek Poplawski
[not found] ` <20080801070150.GB4435-8HppEYmqbBCE+EvaaNYduQ@public.gmane.org>
2008-08-01 7:01 ` David Miller
2008-08-01 7:41 ` Jarek Poplawski
2008-07-25 6:20 ` [lockdep warning] AOE / networking: aoenet_xmit: noop_qdisc.q.lock, INFO: inconsistent lock state at 0000000000000370 Ingo Molnar
2008-07-25 6:25 ` David Miller
2008-07-25 7:26 ` Ingo Molnar
2008-07-25 8:23 ` David Miller
[not found] ` <20080721143023.GA32451-X9Un+BFzKDI@public.gmane.org>
2008-07-21 15:10 ` [crash] BUG: unable to handle kernel NULL pointer dereference " David Miller
2008-07-21 18:23 ` [crash] kernel BUG at net/core/dev.c:1328! Ingo Molnar
2008-07-21 18:35 ` Linus Torvalds
2008-07-21 18:46 ` Ingo Molnar
2008-07-21 19:30 ` Ingo Molnar
2008-07-22 11:21 ` [TCP bug] stuck distcc connections in latest -git Ingo Molnar
2008-07-22 13:45 ` David Newall
2008-07-22 13:57 ` Ingo Molnar
2008-07-22 14:54 ` David Newall
2008-07-22 15:34 ` Ingo Molnar
2008-07-22 21:12 ` Willy Tarreau
2008-07-23 8:26 ` Ingo Molnar
2008-07-24 6:04 ` [TCP bug, regression] " Ingo Molnar
2008-07-24 6:32 ` Ingo Molnar
2008-07-24 7:33 ` Willy Tarreau
2008-07-24 8:35 ` Ingo Molnar
2008-07-24 7:53 ` Herbert Xu
2008-07-24 8:24 ` Willy Tarreau
2008-07-24 8:27 ` Ingo Molnar
2008-07-24 8:36 ` David Miller
2008-07-24 9:05 ` Herbert Xu
2008-07-24 9:22 ` David Miller
2008-07-24 9:34 ` Ingo Molnar
2008-07-24 11:56 ` [regression] nf_iterate(), BUG: unable to handle kernel NULL pointer dereference Ingo Molnar
2008-07-24 11:59 ` Ingo Molnar
2008-07-24 12:03 ` Patrick McHardy
2008-07-24 12:22 ` Herbert Xu
2008-07-24 12:40 ` Pekka Enberg
2008-07-24 12:50 ` Herbert Xu
2008-07-24 12:56 ` Nick Piggin
2008-07-24 13:04 ` Herbert Xu
2008-07-24 13:13 ` Nick Piggin
2008-07-24 13:32 ` Pekka Enberg
2008-07-24 19:21 ` Matt Mackall
2008-07-25 9:09 ` Nick Piggin
2008-07-24 13:11 ` Matt Mackall
2008-07-24 14:37 ` Herbert Xu
2008-07-24 17:47 ` Matt Mackall
2008-07-25 1:39 ` Herbert Xu
2008-07-25 2:59 ` Matt Mackall
2008-07-24 12:44 ` Pekka Enberg
2008-07-24 12:49 ` Patrick McHardy
2008-07-24 13:23 ` Pekka Enberg
2008-07-24 13:31 ` Patrick McHardy
2008-07-24 13:34 ` Pekka Enberg
2008-07-24 18:51 ` Andrew Morton
2008-07-24 18:55 ` Pekka Enberg
2008-07-24 20:58 ` David Miller
2008-07-25 8:02 ` Dieter Ries
2008-07-25 10:41 ` Pekka Enberg
2008-07-24 19:35 ` Ingo Molnar
2008-07-26 16:09 ` Patrick McHardy
2008-07-26 17:34 ` Ingo Molnar
2008-07-26 13:43 ` Patrick McHardy
2008-07-24 21:13 ` Linus Torvalds
2008-07-24 22:09 ` David Miller
2008-07-26 13:47 ` Patrick McHardy
2008-08-01 21:10 ` Paul E. McKenney
2008-07-24 14:23 ` Ingo Molnar
2008-07-24 15:23 ` Patrick McHardy
2008-07-24 15:32 ` Ingo Molnar
2008-07-24 15:34 ` Patrick McHardy
2008-07-24 18:00 ` Krzysztof Oledzki
2008-07-24 13:01 ` [TCP bug, regression] stuck distcc connections in latest -git Willy Tarreau
2008-07-24 9:25 ` Ingo Molnar
2008-07-24 9:29 ` David Miller
2008-07-24 11:12 ` Herbert Xu
2008-07-24 9:36 ` Ilpo Järvinen
2008-07-24 10:03 ` Ilpo Järvinen
2008-07-21 19:00 ` [crash] kernel BUG at net/core/dev.c:1328! David Miller
2008-07-21 19:20 ` Stefan Richter
2008-07-21 20:11 ` David Miller
2008-07-21 21:26 ` Stefan Richter
2008-07-21 19:44 ` Ingo Molnar
2008-07-21 20:20 ` David Miller
2008-07-21 15:07 ` [crash, bisected] Kernel BUG at ffffffff8079afb1 (__netif_schedule()) David Miller
2008-07-21 13:50 ` [GIT]: Networking Ingo Molnar
2008-07-21 14:15 ` Stefan Richter
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