From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: shemminger@vyatta.com, fchecconi@gmail.com, netdev@vger.kernel.org
Subject: Re: [PATCH] net_sched: fix THROTTLED/RUNNING race
Date: Thu, 24 Mar 2011 00:13:46 -0700 (PDT) [thread overview]
Message-ID: <20110324.001346.241938423.davem@davemloft.net> (raw)
In-Reply-To: <1300949637.2810.75.camel@edumazet-laptop>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 24 Mar 2011 07:53:57 +0100
> [PATCH] net_sched: fix THROTTLED/RUNNING race
>
> commit fd245a4adb52 (net_sched: move TCQ_F_THROTTLED flag)
> added a race.
>
> qdisc_watchdog() is run from softirq, so special care should be taken or
> we can lose one state transition (THROTTLED/RUNNING)
>
> Prior to fd245a4adb52, we were manipulating q->flags (qdisc->flags &=
> ~TCQ_F_THROTTLED;) and this manipulation could only race with
> qdisc_warn_nonwc().
>
> Since we want to avoid atomic ops in qdisc fast path - it was the
> meaning of commit 371121057607e (QDISC_STATE_RUNNING dont need atomic
> bit ops) - fix is to move THROTTLE bit into 'state' field, this one
> being manipulated with SMP and IRQ safe operations.
>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Applied, thanks a lot for tracking this down Eric.
next prev parent reply other threads:[~2011-03-24 7:13 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-01 1:17 [PATCH] sched: QFQ - quick fair queue scheduler (v2) Stephen Hemminger
2011-03-01 5:28 ` Eric Dumazet
2011-03-02 2:06 ` Fabio Checconi
2011-03-02 11:17 ` Eric Dumazet
2011-03-02 16:11 ` Stephen Hemminger
2011-03-02 16:18 ` Eric Dumazet
2011-03-02 17:31 ` Eric Dumazet
2011-03-02 18:16 ` Patrick McHardy
2011-03-03 9:35 ` Eric Dumazet
2011-03-02 23:55 ` Stephen Hemminger
2011-03-03 8:19 ` Fabio Checconi
2011-03-03 8:27 ` Eric Dumazet
2011-03-03 10:40 ` Eric Dumazet
2011-03-03 15:07 ` Fabio Checconi
2011-03-03 15:25 ` Eric Dumazet
2011-03-03 15:31 ` Eric Dumazet
2011-03-03 15:39 ` Eric Dumazet
2011-03-03 15:18 ` Eric Dumazet
[not found] ` <20110303161912.GC29685@gandalf.sssup.it>
[not found] ` <1299170053.2983.134.camel@edumazet-laptop>
[not found] ` <20110303181339.GD29685@gandalf.sssup.it>
[not found] ` <1299180567.2547.4.camel@edumazet-laptop>
[not found] ` <1299192974.2547.13.camel@edumazet-laptop>
[not found] ` <20110304064302.GE29685@gandalf.sssup.it>
[not found] ` <1299222074.2547.50.camel@edumazet-laptop>
[not found] ` <AANLkTinAGjZ5SAOA1iUAFu5rtYydeb6Soy_Xg5kMvn-z@mail.gmail.com>
[not found] ` <1299274468.2758.4.camel@edumazet-laptop>
[not found] ` <AANLkTikeQCfShKfZWq2Y7V_MA4iRjQvWWtkC68rK9nUm@mail.gmail.com>
[not found] ` <1299277003.2758.52.camel@edumazet-laptop>
[not found] ` <AANLkTinR7QDC2uGjQurJQ1JfBA7q1pxyewePggh87z8E@mail.gmail.com>
[not found] ` <1299278778.2758.53.camel@edumazet-laptop>
[not found] ` <AANLkTikBoQd+ZA1kY0F0MvUsJ8Y=9KwGkfmZNdi4hLXz@mail.gmail.com>
[not found] ` <20110304150741.5d4aa354@nehalam>
[not found] ` <AANLkTi=HBDayfd0bEA+AQqzjTKMajghet=UJAw9vL56A@mail.gmail.com>
[not found] ` <20110309110242.3307ca69@nehalam>
[not found] ` <1300016057.2761.16.camel@edumazet-laptop>
[not found] ` <1300034690.2761.29.camel@edumazet-laptop>
2011-03-23 6:45 ` [BUG] net_sched: failed bisection Eric Dumazet
2011-03-24 6:53 ` [PATCH] net_sched: fix THROTTLED/RUNNING race Eric Dumazet
2011-03-24 7:13 ` David Miller [this message]
2011-03-03 9:07 ` [PATCH] sched: QFQ - quick fair queue scheduler (v2) Eric Dumazet
2011-03-02 11:50 ` Patrick McHardy
2011-03-02 15:41 ` Eric Dumazet
2011-03-02 15:53 ` Eric Dumazet
2011-03-03 16:03 ` Eric Dumazet
2011-03-03 16:48 ` [PATCH] sched: QFQ - quick fair queue scheduler (v3) Stephen Hemminger
2011-03-03 22:28 ` Eric Dumazet
2011-03-03 22:59 ` Stephen Hemminger
2011-03-03 23:02 ` [PATCH] sched: QFQ - quick fair queue scheduler (v3.1) Stephen Hemminger
2011-03-03 23:12 ` Eric Dumazet
2011-03-04 0:03 ` [PATCH] sched: QFQ - quick fair queue scheduler (v3) Stephen Hemminger
2011-03-04 0:30 ` [PATCH] sched: QFQ - quick fair queue scheduler (v4) Stephen Hemminger
2011-03-04 6:50 ` Eric Dumazet
2011-03-04 17:17 ` Stephen Hemminger
2011-03-04 17:18 ` Stephen Hemminger
2011-03-04 17:20 ` QFQ debugfs Stephen Hemminger
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