From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Julia Cartwright <julia@ni.com>,
Daniel Wagner <daniel.wagner@siemens.com>,
tom.zanussi@linux.intel.com, stable-rt@vger.kernel.org,
Daniel Bristot de Oliveira <bristot@redhat.com>
Subject: [PATCH RT 09/13] hrtimer: move state change before hrtimer_cancel in do_nanosleep()
Date: Mon, 07 Jan 2019 14:53:01 -0500 [thread overview]
Message-ID: <20190107195333.322706801@goodmis.org> (raw)
In-Reply-To: 20190107195252.599921907@goodmis.org
4.14.87-rt50-rc1 stable review patch.
If anyone has any objections, please let me know.
------------------
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ Upstream commit 8115ac730fd5aa27134f002cf710204b5dd7cd5e ]
There is a small window between setting t->task to NULL and waking the
task up (which would set TASK_RUNNING). So the timer would fire, run and
set ->task to NULL while the other side/do_nanosleep() wouldn't enter
freezable_schedule(). After all we are peemptible here (in
do_nanosleep() and on the timer wake up path) and on KVM/virt the
virt-CPU might get preempted.
So do_nanosleep() wouldn't enter freezable_schedule() but cancel the
timer which is still running and wait for it via
hrtimer_wait_for_timer(). Then wait_event()/might_sleep() would complain
that it is invoked with state != TASK_RUNNING.
This isn't a problem since it would be reset to TASK_RUNNING later
anyway and we don't rely on the previous state.
Move the state update to TASK_RUNNING before hrtimer_cancel() so there
are no complains from might_sleep() about wrong state.
Cc: stable-rt@vger.kernel.org
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/time/hrtimer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index b59e009087a9..c8d806126381 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1753,12 +1753,12 @@ static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mod
if (likely(t->task))
freezable_schedule();
+ __set_current_state(TASK_RUNNING);
hrtimer_cancel(&t->timer);
mode = HRTIMER_MODE_ABS;
} while (t->task && !signal_pending(current));
- __set_current_state(TASK_RUNNING);
if (!t->task)
return 0;
--
2.19.2
next prev parent reply other threads:[~2019-01-07 19:54 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-07 19:52 [PATCH RT 00/13] Linux 4.14.87-rt50-rc1 Steven Rostedt
2019-01-07 19:52 ` [PATCH RT 01/13] work-simple: drop a shit statement in SWORK_EVENT_PENDING Steven Rostedt
2019-01-08 3:06 ` Sergey Senozhatsky
2019-01-08 3:26 ` Steven Rostedt
2019-01-08 4:47 ` Sergey Senozhatsky
2019-01-08 9:00 ` Sebastian Andrzej Siewior
2019-01-07 19:52 ` [PATCH RT 02/13] kthread: convert worker lock to raw spinlock Steven Rostedt
2019-01-07 19:52 ` [PATCH RT 03/13] mm/kasan: make quarantine_lock a raw_spinlock_t Steven Rostedt
2019-01-07 19:52 ` [PATCH RT 05/13] sched/migrate_disable: Add export_symbol_gpl for __migrate_disabled Steven Rostedt
2019-01-07 19:52 ` [PATCH RT 06/13] pinctrl: bcm2835: Use raw spinlock for RT compatibility Steven Rostedt
2019-01-07 19:52 ` [PATCH RT 07/13] rcu: make RCU_BOOST default on RT without EXPERT Steven Rostedt
2019-01-07 19:53 ` [PATCH RT 08/13] x86/fpu: Disable preemption around local_bh_disable() Steven Rostedt
2019-01-07 19:53 ` Steven Rostedt [this message]
2019-01-07 19:53 ` [PATCH RT 10/13] drm/i915: disable tracing on -RT Steven Rostedt
2019-01-07 20:10 ` Sebastian Andrzej Siewior
2019-01-07 19:53 ` [PATCH RT 11/13] x86/mm/pat: disable preemption __split_large_page() after spin_lock() Steven Rostedt
2019-01-07 19:53 ` [PATCH RT 13/13] Linux 4.14.87-rt50-rc1 Steven Rostedt
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