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1252ecf63f
ok this is a real potential deadlock in a way, it takes two locks of 2 skbuffs without doing any kind of lock ordering; I think the following patch should fix it. Just sort the lock taking order by address of the skb.. it's not pretty but it's the best this can do in a minimally invasive way. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Chas Williams <chas@cmf.nrl.navy.mil> Signed-off-by: David S. Miller <davem@davemloft.net>
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
/* net/atm/ipcommon.c - Common items for all ways of doing IP over ATM */
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/* Written 1996-2000 by Werner Almesberger, EPFL LRC/ICA */
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <linux/in.h>
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#include <linux/atmdev.h>
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#include <linux/atmclip.h>
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#include "common.h"
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#include "ipcommon.h"
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#if 0
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#define DPRINTK(format,args...) printk(KERN_DEBUG format,##args)
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#else
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#define DPRINTK(format,args...)
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#endif
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/*
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* skb_migrate appends the list at "from" to "to", emptying "from" in the
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* process. skb_migrate is atomic with respect to all other skb operations on
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* "from" and "to". Note that it locks both lists at the same time, so to deal
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* with the lock ordering, the locks are taken in address order.
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*
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* This function should live in skbuff.c or skbuff.h.
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*/
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void skb_migrate(struct sk_buff_head *from, struct sk_buff_head *to)
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{
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unsigned long flags;
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struct sk_buff *skb_from = (struct sk_buff *) from;
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struct sk_buff *skb_to = (struct sk_buff *) to;
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struct sk_buff *prev;
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if ((unsigned long) from < (unsigned long) to) {
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spin_lock_irqsave(&from->lock, flags);
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spin_lock_nested(&to->lock, SINGLE_DEPTH_NESTING);
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} else {
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spin_lock_irqsave(&to->lock, flags);
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spin_lock_nested(&from->lock, SINGLE_DEPTH_NESTING);
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}
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prev = from->prev;
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from->next->prev = to->prev;
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prev->next = skb_to;
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to->prev->next = from->next;
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to->prev = from->prev;
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to->qlen += from->qlen;
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spin_unlock(&to->lock);
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from->prev = skb_from;
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from->next = skb_from;
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from->qlen = 0;
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spin_unlock_irqrestore(&from->lock, flags);
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}
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EXPORT_SYMBOL(skb_migrate);
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