From: Jiri Pirko <jpirko@redhat.com>
Date: Tue, 16 Jun 2009 09:44:19 +0200
Subject: [net] 8139too: RTNL and flush_scheduled_work deadlock
Message-id: 20090616074418.GD3521@psychotron.englab.brq.redhat.com
O-Subject: Re: [RHEL5.5 patch] BZ487346 net: 8139too: RTNL and flush_scheduled_work deadlock [v2]
Bugzilla: 487346
RH-Acked-by: Dean Nelson <dnelson@redhat.com>
RH-Acked-by: Ivan Vecera <ivecera@redhat.com>
RH-Acked-by: David Miller <davem@redhat.com>

BZ487346
https://bugzilla.redhat.com/show_bug.cgi?id=487346

Description:
There's been a possible deadlock during close operation of 8139too NIC on
aquiring RTNL. With this NIC used as bonding slave there was 100% chance
to hit this. This patch fixes the issue.

Upstream:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=83cbb4d2577174e27a91e63a47a2a27c3af50d4e

Brew:
https://brewweb.devel.redhat.com/taskinfo?taskID=1844366

Test:
Booted and tested on x86_64.

Jirka

Signed-off-by: Jiri Pirko <jpirko@redhat.com>

diff --git a/drivers/net/8139too.c b/drivers/net/8139too.c
index 24f561a..c582230 100644
--- a/drivers/net/8139too.c
+++ b/drivers/net/8139too.c
@@ -1112,6 +1112,8 @@ static void __devexit rtl8139_remove_one (struct pci_dev *pdev)
 
 	assert (dev != NULL);
 
+	flush_scheduled_work();
+
 	unregister_netdev (dev);
 
 	__rtl8139_cleanup_dev (dev);
@@ -1605,18 +1607,21 @@ static void rtl8139_thread (void *_data)
 	struct rtl8139_private *tp = netdev_priv(dev);
 	unsigned long thr_delay = next_tick;
 
+	rtnl_lock();
+
+	if (!netif_running(dev))
+		goto out_unlock;
+
 	if (tp->watchdog_fired) {
 		tp->watchdog_fired = 0;
 		rtl8139_tx_timeout_task(_data);
-	} else if (rtnl_trylock()) {
-		rtl8139_thread_iter (dev, tp, tp->mmio_addr);
-		rtnl_unlock ();
-	} else {
-		/* unlikely race.  mitigate with fast poll. */
-		thr_delay = HZ / 2;
-	}
+	} else
+		rtl8139_thread_iter(dev, tp, tp->mmio_addr);
 
-	schedule_delayed_work(&tp->thread, thr_delay);
+	if (tp->have_thread)
+		schedule_delayed_work(&tp->thread, thr_delay);
+out_unlock:
+	rtnl_unlock ();
 }
 
 static void rtl8139_start_thread(struct rtl8139_private *tp)
@@ -1628,19 +1633,11 @@ static void rtl8139_start_thread(struct rtl8139_private *tp)
 		return;
 
 	tp->have_thread = 1;
+	tp->watchdog_fired = 0;
 
 	schedule_delayed_work(&tp->thread, next_tick);
 }
 
-static void rtl8139_stop_thread(struct rtl8139_private *tp)
-{
-	if (tp->have_thread) {
-		cancel_rearming_delayed_work(&tp->thread);
-		tp->have_thread = 0;
-	} else
-		flush_scheduled_work();
-}
-
 static inline void rtl8139_tx_clear (struct rtl8139_private *tp)
 {
 	tp->cur_tx = 0;
@@ -1697,12 +1694,11 @@ static void rtl8139_tx_timeout (struct net_device *dev)
 {
 	struct rtl8139_private *tp = netdev_priv(dev);
 
+	tp->watchdog_fired = 1;
 	if (!tp->have_thread) {
-		INIT_WORK(&tp->thread, rtl8139_tx_timeout_task, dev);
+		INIT_WORK(&tp->thread, rtl8139_thread, dev);
 		schedule_delayed_work(&tp->thread, next_tick);
-	} else
-		tp->watchdog_fired = 1;
-
+	}
 }
 
 static int rtl8139_start_xmit (struct sk_buff *skb, struct net_device *dev)
@@ -2257,8 +2253,6 @@ static int rtl8139_close (struct net_device *dev)
 
 	netif_stop_queue (dev);
 
-	rtl8139_stop_thread(tp);
-
 	if (netif_msg_ifdown(tp))
 		printk(KERN_DEBUG "%s: Shutting down ethercard, status was 0x%4.4x.\n",
 			dev->name, RTL_R16 (IntrStatus));