Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Ingo Molnar:
"Three fixes: fix link failure on Alpha, fix a Sparse warning and
annotate/robustify a lockless access in the NOHZ code"
* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tick/sched: Annotate lockless access to last_jiffies_update
lib/vdso: Make __cvdso_clock_getres() static
time/posix-stubs: Provide compat itimer supoprt for alpha
+13
-5
+3
kernel/time/posix-stubs.c
+3
kernel/time/posix-stubs.c
+9
-5
kernel/time/tick-sched.c
+9
-5
kernel/time/tick-sched.c
···
58
58
59
59
/*
60
60
* Do a quick check without holding jiffies_lock:
61
+
* The READ_ONCE() pairs with two updates done later in this function.
61
62
*/
62
-
delta = ktime_sub(now, last_jiffies_update);
63
+
delta = ktime_sub(now, READ_ONCE(last_jiffies_update));
63
64
if (delta < tick_period)
64
65
return;
65
66
···
71
70
if (delta >= tick_period) {
72
71
73
72
delta = ktime_sub(delta, tick_period);
74
-
last_jiffies_update = ktime_add(last_jiffies_update,
75
-
tick_period);
73
+
/* Pairs with the lockless read in this function. */
74
+
WRITE_ONCE(last_jiffies_update,
75
+
ktime_add(last_jiffies_update, tick_period));
76
76
77
77
/* Slow path for long timeouts */
78
78
if (unlikely(delta >= tick_period)) {
···
81
79
82
80
ticks = ktime_divns(delta, incr);
83
81
84
-
last_jiffies_update = ktime_add_ns(last_jiffies_update,
85
-
incr * ticks);
82
+
/* Pairs with the lockless read in this function. */
83
+
WRITE_ONCE(last_jiffies_update,
84
+
ktime_add_ns(last_jiffies_update,
85
+
incr * ticks));
86
86
}
87
87
do_timer(++ticks);
88
88