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authorLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-19 11:54:39 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-19 11:54:39 -0700
commit804b908adfcffe3831621acb6c8a776585983d2a (patch)
tree9664d4395ae8e590e50c568225ea88435383ed99 /net/sched
parent1b3e4c706c19dec10b11dac1b23071e3e4b262ad (diff)
parentce0e32e65f70337e0732c97499b643205fa8ea31 (diff)
downloadlinux-804b908adfcffe3831621acb6c8a776585983d2a.tar.gz
Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
* 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6:
  [NET]: Fix possible dev_deactivate race condition
  [INET]: Justification for local port range robustness.
  [PACKET]: Kill unused pg_vec_endpage() function
  [NET]: QoS/Sched as menuconfig
  [NET]: Fix bug in sk_filter race cures.
  [PATCH] mac80211: make ieee802_11_parse_elems return void
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/Kconfig10
-rw-r--r--net/sched/sch_generic.c26
2 files changed, 26 insertions, 10 deletions
diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index 92435a882fac..9c15c4888d12 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig
@@ -2,9 +2,7 @@
 # Traffic control configuration.
 # 
 
-menu "QoS and/or fair queueing"
-
-config NET_SCHED
+menuconfig NET_SCHED
 	bool "QoS and/or fair queueing"
 	select NET_SCH_FIFO
 	---help---
@@ -41,9 +39,6 @@ config NET_SCHED
 	  The available schedulers are listed in the following questions; you
 	  can say Y to as many as you like. If unsure, say N now.
 
-config NET_SCH_FIFO
-	bool
-
 if NET_SCHED
 
 comment "Queueing/Scheduling"
@@ -500,4 +495,5 @@ config NET_CLS_IND
 
 endif # NET_SCHED
 
-endmenu
+config NET_SCH_FIFO
+	bool
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index e01d57692c9a..fa1a6f45dc41 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -556,6 +556,7 @@ void dev_deactivate(struct net_device *dev)
 {
 	struct Qdisc *qdisc;
 	struct sk_buff *skb;
+	int running;
 
 	spin_lock_bh(&dev->queue_lock);
 	qdisc = dev->qdisc;
@@ -571,12 +572,31 @@ void dev_deactivate(struct net_device *dev)
 
 	dev_watchdog_down(dev);
 
-	/* Wait for outstanding dev_queue_xmit calls. */
+	/* Wait for outstanding qdisc-less dev_queue_xmit calls. */
 	synchronize_rcu();
 
 	/* Wait for outstanding qdisc_run calls. */
-	while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
-		yield();
+	do {
+		while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
+			yield();
+
+		/*
+		 * Double-check inside queue lock to ensure that all effects
+		 * of the queue run are visible when we return.
+		 */
+		spin_lock_bh(&dev->queue_lock);
+		running = test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
+		spin_unlock_bh(&dev->queue_lock);
+
+		/*
+		 * The running flag should never be set at this point because
+		 * we've already set dev->qdisc to noop_qdisc *inside* the same
+		 * pair of spin locks.  That is, if any qdisc_run starts after
+		 * our initial test it should see the noop_qdisc and then
+		 * clear the RUNNING bit before dropping the queue lock.  So
+		 * if it is set here then we've found a bug.
+		 */
+	} while (WARN_ON_ONCE(running));
 }
 
 void dev_init_scheduler(struct net_device *dev)