From: Patrick McHardy <kaber@trash.net>
To: Eric Lemoine <eric.lemoine@gmail.com>
Cc: netdev@oss.sgi.com, hadi@cyberus.ca,
"David S. Miller" <davem@davemloft.net>,
openib-general@openib.org
Subject: Re: LLTX and netif_stop_queue
Date: Thu, 23 Dec 2004 17:37:24 +0100 [thread overview]
Message-ID: <41CAF444.3000305@trash.net> (raw)
In-Reply-To: <5cac192f0412230110628749e3@mail.gmail.com>
Eric Lemoine wrote:
> I still have one concern with the LLTX code (and it may be that the
> correct patch is Jamal's) :
>
> Without LLTX we do : lock(queue_lock), lock(xmit_lock),
> release(queue_lock), release(xmit_lock). With LLTX (without Jamal's
> patch) we do : lock(queue_lock), release(queue_lock), lock(tx_lock),
> release(tx_lock). LLTX doesn't look correct because it creates a race
> condition window between the the two lock-protected sections. So you
> may want to reconsider Jamal's patch or pull out LLTX...
You're right, it can cause packet reordering if something like this
happens:
CPU1 CPU2
lock(queue_lock)
dequeue
unlock(queue_lock)
lock(queue_lock)
dequeue
unlock(queue_lock)
lock(xmit_lock)
hard_start_xmit
unlock(xmit_lock)
lock(xmit_lock)
hard_start_xmit
unlock(xmit_lock)
Jamal's patch should fix this.
Regards
Patrick
next prev parent reply other threads:[~2004-12-23 16:37 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-17 21:57 LLTX and netif_stop_queue Roland Dreier
2004-12-18 5:44 ` David S. Miller
2004-12-18 15:35 ` Roland Dreier
2004-12-18 17:58 ` Roland Dreier
2004-12-18 18:26 ` Roland Dreier
2004-12-19 19:33 ` jamal
2004-12-19 19:31 ` jamal
2004-12-19 19:54 ` jamal
2004-12-19 20:02 ` Jamal Hadi Salim
2004-12-19 22:35 ` Roland Dreier
2004-12-19 23:06 ` jamal
2004-12-19 23:16 ` Roland Dreier
2004-12-22 18:49 ` Eric Lemoine
2004-12-23 4:29 ` David S. Miller
2004-12-23 4:38 ` Roland Dreier
2004-12-23 9:10 ` Eric Lemoine
2004-12-23 16:37 ` Patrick McHardy [this message]
2004-12-23 18:11 ` Eric Lemoine
2004-12-24 16:10 ` Eric Lemoine
2004-12-28 13:31 ` jamal
2005-01-02 23:30 ` Eric Lemoine
2005-01-03 7:41 ` Eric Lemoine
2005-01-03 15:04 ` jamal
2005-01-03 15:48 ` Eric Lemoine
2005-01-03 15:57 ` Roland Dreier
2005-01-03 16:41 ` Eric Lemoine
2005-01-03 16:54 ` Roland Dreier
2005-01-03 17:07 ` Eric Lemoine
2005-01-03 17:12 ` Grant Grundler
2005-01-04 4:18 ` jamal
2005-01-19 22:47 ` David S. Miller
2005-01-19 23:18 ` Stephen Hemminger
2005-01-19 23:41 ` David S. Miller
2005-01-20 0:02 ` [openib-general] " Jeff Garzik
2005-01-20 0:46 ` Stephen Hemminger
2005-01-20 0:47 ` David S. Miller
2005-01-20 0:47 ` Francois Romieu
2005-01-20 0:52 ` David S. Miller
2005-01-20 1:17 ` Francois Romieu
2005-01-20 0:46 ` [PATCH]: was " David S. Miller
2005-01-20 3:14 ` Andi Kleen
2005-01-20 7:05 ` David S. Miller
2005-01-20 3:43 ` Roland Dreier
2005-01-20 7:05 ` David S. Miller
2005-01-20 13:51 ` Tommy Christensen
2005-01-20 21:34 ` David S. Miller
2005-01-20 21:56 ` Grant Grundler
2005-01-21 1:01 ` David S. Miller
2005-01-22 3:17 ` Roland Dreier
2005-01-22 3:53 ` David S. Miller
2005-01-20 21:41 ` David S. Miller
2005-01-20 16:56 ` Stephen Hemminger
2005-01-21 10:54 ` Lennert Buytenhek
2005-01-26 6:27 ` David S. Miller
2005-01-26 13:25 ` Lennert Buytenhek
2005-01-27 6:32 ` David S. Miller
2005-01-27 7:16 ` Andi Kleen
2005-01-27 7:22 ` David S. Miller
2005-01-27 8:26 ` Andi Kleen
2005-01-20 19:16 ` Jeff Garzik
2005-01-20 4:01 ` jamal
2005-01-20 5:18 ` David S. Miller
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