linux-kernel - [tip:sched/core] netdev, sched/wait: Fix sleeping inside wait event

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Date:	Tue, 4 Nov 2014 08:09:20 -0800
From:	tip-bot for Peter Zijlstra <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, edumazet@...gle.com, david@...son.dropbear.id.au,
	linux-kernel@...r.kernel.org, peterz@...radead.org,
	tglx@...utronix.de, jhs@...atatu.com, teg@...m.no,
	nicolas.dichtel@...nd.com, cwang@...pensource.com,
	vyasevic@...hat.com, ebiederm@...ssion.com, jiri@...nulli.us,
	vfalico@...il.com, oleg@...hat.com, torvalds@...ux-foundation.org,
	hkchu@...gle.com, stephen@...workplumber.org,
	john.fastabend@...il.com, therbert@...gle.com,
	fengguang.wu@...el.com, sfeldma@...ulusnetworks.com,
	davem@...emloft.net, hpa@...or.com
Subject: [tip:sched/core] netdev, sched/wait:
  Fix sleeping inside wait event

Commit-ID:  ff960a731788a7408b6f66ec4fd772ff18833211
Gitweb:     http://git.kernel.org/tip/ff960a731788a7408b6f66ec4fd772ff18833211
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Wed, 29 Oct 2014 17:04:56 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 4 Nov 2014 07:17:48 +0100

netdev, sched/wait: Fix sleeping inside wait event

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@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: David S. Miller <davem@...emloft.net>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Cong Wang <cwang@...pensource.com>
Cc: David Gibson <david@...son.dropbear.id.au>
Cc: Eric Biederman <ebiederm@...ssion.com>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Jerry Chu <hkchu@...gle.com>
Cc: Jiri Pirko <jiri@...nulli.us>
Cc: John Fastabend <john.fastabend@...il.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc: sfeldma@...ulusnetworks.com <sfeldma@...ulusnetworks.com>
Cc: stephen hemminger <stephen@...workplumber.org>
Cc: Tom Gundersen <teg@...m.no>
Cc: Tom Herbert <therbert@...gle.com>
Cc: Veaceslav Falico <vfalico@...il.com>
Cc: Vlad Yasevich <vyasevic@...hat.com>
Cc: netdev@...r.kernel.org
Link: http://lkml.kernel.org/r/20141029173110.GE15602@worktop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 net/core/dev.c       | 10 +++++-----
 net/core/rtnetlink.c | 10 +++++-----
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index b793e35..c5a9d73 100644
--- 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
index a688268..b095296 100644
--- 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);
 }
 
 /**
--
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