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Message-ID: <3E10C991.4060807@colorfullife.com>
Date: Mon, 30 Dec 2002 23:32:49 +0100
From: Manfred Spraul <manfred@colorfullife.com>
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To: Muli Ben-Yehuda <mulix@mulix.org>
CC: Oliver Neukum <oliver@neukum.name>, linux-kernel@vger.kernel.org
Subject: Re: question on context of kfree_skb()
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Mulix wrote:

>dev_kfree_skb_any() should be called when you could be either
>executing in interrupt context or not. 
>
dev_kfree_skb_any() can misdetect the context: You must not use the 
function if you hold an irq spinlock and you might be running from BH or 
process context.

cpu 1:    cpu 2:
acquire one of the networking bh lock
             acquire the driver spin_lock_irq()
hardware interrupt
try to acquire the driver irq spinlock
--> spin.
              dev_kfree_skb_any(): !in_irq(), calls kfree_skb
              kfree_skb tries to acquire the network lock that
              cpu 1 owns
              --> spin.

And deadlock.

--
    Manfred



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