From: paulmck@kernel.org
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 3/9] timer: Use hlist_unhashed_lockless() in timer_pending()
Date: Mon, 9 Dec 2019 20:19:56 -0800 [thread overview]
Message-ID: <20191210042002.3490-3-paulmck@kernel.org> (raw)
In-Reply-To: <20191210041938.GA3367@paulmck-ThinkPad-P72>
From: Eric Dumazet <edumazet@google.com>
The timer_pending() function is mostly used in lockless contexts, so
Without proper annotations, KCSAN might detect a data-race [1].
Using hlist_unhashed_lockless() instead of hand-coding it seems
appropriate (as suggested by Paul E. McKenney).
[1]
BUG: KCSAN: data-race in del_timer / detach_if_pending
write to 0xffff88808697d870 of 8 bytes by task 10 on cpu 0:
__hlist_del include/linux/list.h:764 [inline]
detach_timer kernel/time/timer.c:815 [inline]
detach_if_pending+0xcd/0x2d0 kernel/time/timer.c:832
try_to_del_timer_sync+0x60/0xb0 kernel/time/timer.c:1226
del_timer_sync+0x6b/0xa0 kernel/time/timer.c:1365
schedule_timeout+0x2d2/0x6e0 kernel/time/timer.c:1896
rcu_gp_fqs_loop+0x37c/0x580 kernel/rcu/tree.c:1639
rcu_gp_kthread+0x143/0x230 kernel/rcu/tree.c:1799
kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352
read to 0xffff88808697d870 of 8 bytes by task 12060 on cpu 1:
del_timer+0x3b/0xb0 kernel/time/timer.c:1198
sk_stop_timer+0x25/0x60 net/core/sock.c:2845
inet_csk_clear_xmit_timers+0x69/0xa0 net/ipv4/inet_connection_sock.c:523
tcp_clear_xmit_timers include/net/tcp.h:606 [inline]
tcp_v4_destroy_sock+0xa3/0x3f0 net/ipv4/tcp_ipv4.c:2096
inet_csk_destroy_sock+0xf4/0x250 net/ipv4/inet_connection_sock.c:836
tcp_close+0x6f3/0x970 net/ipv4/tcp.c:2497
inet_release+0x86/0x100 net/ipv4/af_inet.c:427
__sock_release+0x85/0x160 net/socket.c:590
sock_close+0x24/0x30 net/socket.c:1268
__fput+0x1e1/0x520 fs/file_table.c:280
____fput+0x1f/0x30 fs/file_table.c:313
task_work_run+0xf6/0x130 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x2b4/0x2c0 arch/x86/entry/common.c:163
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 12060 Comm: syz-executor.5 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine,
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
include/linux/timer.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/timer.h b/include/linux/timer.h
index 1e6650e..0dc19a8 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -164,7 +164,7 @@ static inline void destroy_timer_on_stack(struct timer_list *timer) { }
*/
static inline int timer_pending(const struct timer_list * timer)
{
- return timer->entry.pprev != NULL;
+ return !hlist_unhashed_lockless(&timer->entry);
}
extern void add_timer_on(struct timer_list *timer, int cpu);
--
2.9.5
next prev parent reply other threads:[~2019-12-10 4:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-10 4:19 [PATCH tip/core/rcu 0/9] RCU list updates for v5.6 Paul E. McKenney
2019-12-10 4:19 ` [PATCH tip/core/rcu 1/9] rculist: Describe variadic macro argument in a Sphinx-compatible way paulmck
2019-12-10 4:19 ` [PATCH tip/core/rcu 2/9] list: Add hlist_unhashed_lockless() paulmck
2019-12-10 4:19 ` paulmck [this message]
2019-12-10 4:19 ` [PATCH tip/core/rcu 4/9] rcu: Use WRITE_ONCE() for assignments to ->pprev for hlist_nulls paulmck
2019-12-10 4:19 ` [PATCH tip/core/rcu 5/9] rcu: Add and update docbook header comments in list.h paulmck
2019-12-10 4:19 ` [PATCH tip/core/rcu 6/9] rcu: Add a hlist_nulls_unhashed_lockless() function paulmck
2019-12-10 4:20 ` [PATCH tip/core/rcu 7/9] rculist_nulls: Add docbook comments paulmck
2019-12-10 4:20 ` [PATCH tip/core/rcu 8/9] rculist_nulls: Change docbook comment headers paulmck
2019-12-10 4:20 ` [PATCH tip/core/rcu 9/9] rculist.h: Add list_tail_rcu() paulmck
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