From: Stephen Hemminger Date: Wed, 27 Jun 2007 07:39:42 +0000 (-0700) Subject: [NETPOLL]: tx lock deadlock fix X-Git-Tag: v2.6.22-rc7~12^2~3 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0db3dc73f7a3a73b0dc725b6a991253f5652c905;p=linux-2.6 [NETPOLL]: tx lock deadlock fix 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 Signed-off-by: David S. Miller --- diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 758dafe284..f8e74e511c 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -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); }