From: Stephen Hemminger <stephen@networkplumber.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>, netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH v3 net] net: solve a NAPI race
Date: Tue, 28 Feb 2017 08:17:02 -0800 [thread overview]
Message-ID: <20170228081702.35ba7a6a@xeon-e3> (raw)
In-Reply-To: <1488226711.9415.204.camel@edumazet-glaptop3.roam.corp.google.com>
On Mon, 27 Feb 2017 12:18:31 -0800
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> This can happen with busy polling users, or if gro_flush_timeout is
> used. But some other uses of napi_schedule() in drivers can cause this
> as well.
Where were IRQ's re-enabled?
> thread 1 thread 2 (could be on same cpu)
>
> // busy polling or napi_watchdog()
> napi_schedule();
> ...
> napi->poll()
>
> device polling:
> read 2 packets from ring buffer
> Additional 3rd packet is available.
> device hard irq
>
> // does nothing because NAPI_STATE_SCHED bit is owned by thread 1
> napi_schedule();
>
> napi_complete_done(napi, 2);
> rearm_irq();
Maybe just as simple as using irqsave/irqrestore in driver.
next prev parent reply other threads:[~2017-02-28 16:17 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-25 14:22 [PATCH net] net/mlx4_en: reception NAPI/IRQ race breaker Eric Dumazet
2017-02-26 16:32 ` Saeed Mahameed
2017-02-26 17:34 ` Eric Dumazet
2017-02-26 17:40 ` Eric Dumazet
2017-02-26 18:03 ` Eric Dumazet
2017-02-27 3:31 ` [PATCH net] net: solve a NAPI race Eric Dumazet
2017-02-27 14:06 ` Eric Dumazet
2017-02-27 14:21 ` [PATCH v2 " Eric Dumazet
2017-02-27 16:19 ` David Miller
2017-02-27 16:44 ` Eric Dumazet
2017-02-27 17:10 ` Eric Dumazet
2017-02-28 2:08 ` David Miller
2017-03-01 0:22 ` Francois Romieu
2017-03-01 1:04 ` Stephen Hemminger
2017-02-27 21:00 ` Alexander Duyck
2017-02-27 20:18 ` [PATCH v3 " Eric Dumazet
2017-02-27 22:14 ` Stephen Hemminger
2017-02-27 22:35 ` Eric Dumazet
2017-02-27 22:44 ` Stephen Hemminger
2017-02-27 22:48 ` David Miller
2017-02-27 23:23 ` Stephen Hemminger
2017-02-28 10:14 ` David Laight
2017-02-28 13:04 ` Eric Dumazet
2017-02-28 13:20 ` Eric Dumazet
2017-02-28 16:17 ` Stephen Hemminger [this message]
2017-02-28 16:57 ` Eric Dumazet
2017-02-28 18:34 ` [PATCH v4 " Eric Dumazet
2017-03-01 17:53 ` David Miller
2017-02-28 17:20 ` [PATCH v2 " Alexander Duyck
2017-02-28 17:47 ` Eric Dumazet
2017-03-01 10:41 ` David Laight
2017-03-01 16:14 ` Alexander Duyck
2017-03-01 17:32 ` Eric Dumazet
2017-03-02 10:24 ` David Laight
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