lkml.org 
[lkml]   [2015]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 1/3] hrtimer: kill HRTIMER_STATE_MIGRATE, fix the race with hrtimer_is_queued()
migrate_hrtimer_list() sets HRTIMER_STATE_MIGRATE to avoid the
race with hrtimer_active(), but this can't avoid the same race
with hrtimer_is_queued().

Kill HRTIMER_STATE_MIGRATE, we can simply use STATE_ENQUEUED.
---
include/linux/hrtimer.h | 6 +-----
kernel/time/hrtimer.c | 7 ++-----
2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index 05f6df1..44810bc 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -70,17 +70,13 @@ enum hrtimer_restart {
* the handling of the timer.
*
* The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state
- * to preserve the HRTIMER_STATE_CALLBACK in the above scenario. This
- * also affects HRTIMER_STATE_MIGRATE where the preservation is not
- * necessary. HRTIMER_STATE_MIGRATE is cleared after the timer is
- * enqueued on the new cpu.
+ * to preserve the HRTIMER_STATE_CALLBACK in the above scenario.
*
* All state transitions are protected by cpu_base->lock.
*/
#define HRTIMER_STATE_INACTIVE 0x00
#define HRTIMER_STATE_ENQUEUED 0x01
#define HRTIMER_STATE_CALLBACK 0x02
-#define HRTIMER_STATE_MIGRATE 0x04

/**
* struct hrtimer - the basic hrtimer structure
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 76d4bd9..005fd44 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1640,11 +1640,11 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
debug_deactivate(timer);

/*
- * Mark it as STATE_MIGRATE not INACTIVE otherwise the
+ * Mark it as ENQUEUED not INACTIVE otherwise the
* timer could be seen as !active and just vanish away
* under us on another CPU
*/
- __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
+ __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
timer->base = new_base;
/*
* Enqueue the timers on the new cpu. This does not
@@ -1655,9 +1655,6 @@ static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
* event device.
*/
enqueue_hrtimer(timer, new_base);
-
- /* Clear the migration state bit */
- timer->state &= ~HRTIMER_STATE_MIGRATE;
}
}

--
1.5.5.1



\
 
 \ /
  Last update: 2015-06-08 17:41    [W:0.119 / U:0.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site