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To: Werner Almesberger <wa@almesberger.net>
cc: "David S. Miller" <davem@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][ATM] make atm (and clip) modular + try_module_get() 
In-reply-to: Your message of "Mon, 03 Mar 2003 23:07:06 -0300."
             <20030303230706.R2791@almesberger.net> 
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Date: Wed, 05 Mar 2003 09:47:38 -0500
From: chas williams <chas@locutus.cmf.nrl.navy.mil>
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In message <20030303230706.R2791@almesberger.net>,Werner Almesberger writes:
>see getting moved to net/core/skbuff.c, because it seems to provide
>a reasonably generic function.

it has been suggested to me that the locking in skb_migrate might not be
completely correct.  any comments on the following?

        spinlock_t *first, *second;
        if ((unsigned long)from < (unsigned long) to)) {
                first = &from->lock;
                second = &to->lock;
        } else {
                first = &to->lock;
                second = &from->lock;
        }

        local_irq_save(flags);
        spin_lock(&first);
        spin_lock(&second);

i imagine this is to prevent deadlocks when you do something silly like
skb_migrate(a,b) and then skb_migrate(b,a) elsewhere.
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