RE: [2.6.5] Bad scheduling while atomic

From: Paul Rolland
Date: Sun Apr 18 2004 - 13:52:27 EST


Thanks Stephen for being so fast !

Regards,
Paul

Paul Rolland, rol(at)as2917.net
ex-AS2917 Network administrator and Peering Coordinator

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> -----Message d'origine-----
> De : linux-kernel-owner@xxxxxxxxxxxxxxx
> [mailto:linux-kernel-owner@xxxxxxxxxxxxxxx] De la part de
> Stephen Hemminger
> Envoyé : vendredi 16 avril 2004 22:17
> À : David S. Miller
> Cc : Paul Rolland; linux-kernel@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxx
> Objet : Re: [2.6.5] Bad scheduling while atomic
>
> Bring up/down network devices with lapbether causes scheduling while
> atomic (if preempt enabled).
>
> The calls to rcu_read_lock are unnecessary since lapb_device_event
> is called from notifier with the rtnetlink semaphore held, it is
> already protected from the labp_devices list changing.
>
> Patch against 2.6.6-rc1
>
> diff -Nru a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c
> --- a/drivers/net/wan/lapbether.c Fri Apr 16 11:00:35 2004
> +++ b/drivers/net/wan/lapbether.c Fri Apr 16 11:00:35 2004
> @@ -392,6 +392,8 @@
>
> /*
> * Handle device status changes.
> + *
> + * Called from notifier with RTNL held.
> */
> static int lapbeth_device_event(struct notifier_block *this,
> unsigned long event, void *ptr)
> @@ -402,7 +404,6 @@
> if (!dev_is_ethdev(dev))
> return NOTIFY_DONE;
>
> - rcu_read_lock();
> switch (event) {
> case NETDEV_UP:
> /* New ethernet device -> new LAPB interface */
> @@ -422,7 +423,6 @@
> lapbeth_free_device(lapbeth);
> break;
> }
> - rcu_read_unlock();
>
> return NOTIFY_DONE;
> }
> -
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