From: Jeff Garzik <jgarzik@pobox•com>
To: Matti Linnanvuori <mattilinnanvuori@yahoo•com>
Cc: netdev@vger•kernel.org, David Miller <davem@davemloft•net>
Subject: Re: [Bug 9750] [patch 2.6.25] dev: avoid a race that triggers assertion failure
Date: Tue, 12 Feb 2008 10:58:12 -0500 [thread overview]
Message-ID: <47B1C214.2060600@pobox.com> (raw)
In-Reply-To: <190693.34289.qm@web52005.mail.re2.yahoo.com>
Matti Linnanvuori wrote:
> From: Matti Linnanvuori <mattilinnanvuori@yahoo•com>
>
> There is a race in Linux kernel file net/core/dev.c, function dev_close.
> The function calls function dev_deactivate, which calls function
> dev_watchdog_down that deletes the watchdog timer. However, after that, a
> driver can call netif_carrier_ok, which calls function
> __netdev_watchdog_up that can add the watchdog timer again. Function
> unregister_netdevice calls function dev_shutdown that traps the bug
> !timer_pending(&dev->watchdog_timer). Moving dev_deactivate after
> netif_running() has been cleared prevents function netif_carrier_on
> from calling __netdev_watchdog_up and adding the watchdog timer again.
>
> Signed-off-by: Matti Linnanvuori <mattilinnanvuori@yahoo•com>
>
> ---
>
> --- linux-2.6.25/net/core/dev.c 2008-02-12 12:37:51.206833000 +0200
> +++ b/net/core/dev.c 2008-02-12 12:38:48.727611400 +0200
> @@ -1071,8 +1071,6 @@ int dev_close(struct net_device *dev)
> */
> call_netdevice_notifiers(NETDEV_GOING_DOWN, dev);
>
> - dev_deactivate(dev);
> -
> clear_bit(__LINK_STATE_START, &dev->state);
>
> /* Synchronize to scheduled poll. We cannot touch poll list,
> @@ -1083,6 +1081,7 @@ int dev_close(struct net_device *dev)
> */
> smp_mb__after_clear_bit(); /* Commit netif_running(). */
>
> + dev_deactivate(dev);
> /*
> * Call the device specific close. This cannot fail.
> * Only if device is UP
This is more for davem (he does net/* stuff)
Jeff
next prev parent reply other threads:[~2008-02-12 15:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-12 10:45 [Bug 9750] [patch 2.6.25] dev: avoid a race that triggers assertion failure Matti Linnanvuori
2008-02-12 15:58 ` Jeff Garzik [this message]
2008-02-13 2:16 ` David Miller
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