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[NETPOLL]: tx lock deadlock fix

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If sky2 device poll routine is called from netpoll_send_skb, it would
deadlock. The netpoll_send_skb held the netif_tx_lock, and the poll
routine could acquire it to clean up skb's. Other drivers might use
same locking model.

The driver is correct, netpoll should not introduce more locking
problems than it causes already. So change the code to drop lock
before calling poll handler.

Signed-off-by: Stephen Hemminger <shemminger@linux.foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2007-06-27 00:39:42 -07:00 committed by David S. Miller
parent 48d8d7ee5d
commit 0db3dc73f7
1 changed files with 10 additions and 9 deletions
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19
net/core/netpoll.c
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@ -250,22 +250,23 @@ static void netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
unsigned long flags;
local_irq_save(flags);
if (netif_tx_trylock(dev)) {
/* try until next clock tick */
for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
tries > 0; --tries) {
/* try until next clock tick */
for (tries = jiffies_to_usecs(1)/USEC_PER_POLL;
tries > 0; --tries) {
if (netif_tx_trylock(dev)) {
if (!netif_queue_stopped(dev))
status = dev->hard_start_xmit(skb, dev);
netif_tx_unlock(dev);
if (status == NETDEV_TX_OK)
break;
/* tickle device maybe there is some cleanup */
netpoll_poll(np);
udelay(USEC_PER_POLL);
}
netif_tx_unlock(dev);
/* tickle device maybe there is some cleanup */
netpoll_poll(np);
udelay(USEC_PER_POLL);
}
local_irq_restore(flags);
}