netdev, sched/wait: Fix sleeping inside wait event

Peter Zijlstra · Ingo Molnar · commit ff960a731788 · 2014-11-04T07:17:48.000+01:00
rtnl_lock_unregistering*() take rtnl_lock() -- a mutex -- inside a wait loop. The wait loop relies on current->state to function, but so does mutex_lock(), nesting them makes for the inner to destroy the outer state. Fix this using the new wait_woken() bits. Reported-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: David S. Miller <davem@davemloft.net> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Cong Wang <cwang@twopensource.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: Jerry Chu <hkchu@google.com> Cc: Jiri Pirko <jiri@resnulli.us> Cc: John Fastabend <john.fastabend@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com> Cc: sfeldma@cumulusnetworks.com <sfeldma@cumulusnetworks.com> Cc: stephen hemminger <stephen@networkplumber.org> Cc: Tom Gundersen <teg@jklm.no> Cc: Tom Herbert <therbert@google.com> Cc: Veaceslav Falico <vfalico@gmail.com> Cc: Vlad Yasevich <vyasevic@redhat.com> Cc: netdev@vger.kernel.org Link: http://lkml.kernel.org/r/20141029173110.GE15602@worktop.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/net/core/dev.c b/net/core/dev.c
@@ -7196,11 +7196,10 @@ static void __net_exit rtnl_lock_unregistering(struct list_head *net_list)
 	 */
 	struct net *net;
 	bool unregistering;
-	DEFINE_WAIT(wait);
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 
+	add_wait_queue(&netdev_unregistering_wq, &wait);
 	for (;;) {
-		prepare_to_wait(&netdev_unregistering_wq, &wait,
-				TASK_UNINTERRUPTIBLE);
 		unregistering = false;
 		rtnl_lock();
 		list_for_each_entry(net, net_list, exit_list) {
@@ -7212,9 +7211,10 @@ static void __net_exit rtnl_lock_unregistering(struct list_head *net_list)
 		if (!unregistering)
 			break;
 		__rtnl_unlock();
-		schedule();
+
+		wait_woken(&wait, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
 	}
-	finish_wait(&netdev_unregistering_wq, &wait);
+	remove_wait_queue(&netdev_unregistering_wq, &wait);
 }
 
 static void __net_exit default_device_exit_batch(struct list_head *net_list)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
@@ -365,11 +365,10 @@ static void rtnl_lock_unregistering_all(void)
 {
 	struct net *net;
 	bool unregistering;
-	DEFINE_WAIT(wait);
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
 
+	add_wait_queue(&netdev_unregistering_wq, &wait);
 	for (;;) {
-		prepare_to_wait(&netdev_unregistering_wq, &wait,
-				TASK_UNINTERRUPTIBLE);
 		unregistering = false;
 		rtnl_lock();
 		for_each_net(net) {
@@ -381,9 +380,10 @@ static void rtnl_lock_unregistering_all(void)
 		if (!unregistering)
 			break;
 		__rtnl_unlock();
-		schedule();
+
+		wait_woken(&wait, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
 	}
-	finish_wait(&netdev_unregistering_wq, &wait);
+	remove_wait_queue(&netdev_unregistering_wq, &wait);
 }
 
 /**
