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authorLinus Torvalds <torvalds@linux-foundation.org>2020-01-18 13:00:59 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-01-18 13:00:59 -0800
commit7ff15cd0458c288afa954de843bb1903c723e5b3 (patch)
treeba2cd2cee87452b4d337b8a529b7f8d18b23ad0f
parent9e79c5233290884d54addb601afc7ece2f70c79e (diff)
parentde95a991bb72e009f47e0c4bbc90fc5f594588d5 (diff)
downloadlinux-7ff15cd0458c288afa954de843bb1903c723e5b3.tar.bz2
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
-rw-r--r--kernel/time/posix-stubs.c3
-rw-r--r--kernel/time/tick-sched.c14
-rw-r--r--lib/vdso/gettimeofday.c1
3 files changed, 13 insertions, 5 deletions
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 67df65f887ac..20c65a7d4e3a 100644
--- a/kernel/time/posix-stubs.c
+++ b/kernel/time/posix-stubs.c
@@ -151,6 +151,9 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
#ifdef CONFIG_COMPAT
COMPAT_SYS_NI(timer_create);
+#endif
+
+#if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
COMPAT_SYS_NI(getitimer);
COMPAT_SYS_NI(setitimer);
#endif
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 8b192e67aabc..a792d21cac64 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -58,8 +58,9 @@ static void tick_do_update_jiffies64(ktime_t now)
/*
* Do a quick check without holding jiffies_lock:
+ * The READ_ONCE() pairs with two updates done later in this function.
*/
- delta = ktime_sub(now, last_jiffies_update);
+ delta = ktime_sub(now, READ_ONCE(last_jiffies_update));
if (delta < tick_period)
return;
@@ -70,8 +71,9 @@ static void tick_do_update_jiffies64(ktime_t now)
if (delta >= tick_period) {
delta = ktime_sub(delta, tick_period);
- last_jiffies_update = ktime_add(last_jiffies_update,
- tick_period);
+ /* Pairs with the lockless read in this function. */
+ WRITE_ONCE(last_jiffies_update,
+ ktime_add(last_jiffies_update, tick_period));
/* Slow path for long timeouts */
if (unlikely(delta >= tick_period)) {
@@ -79,8 +81,10 @@ static void tick_do_update_jiffies64(ktime_t now)
ticks = ktime_divns(delta, incr);
- last_jiffies_update = ktime_add_ns(last_jiffies_update,
- incr * ticks);
+ /* Pairs with the lockless read in this function. */
+ WRITE_ONCE(last_jiffies_update,
+ ktime_add_ns(last_jiffies_update,
+ incr * ticks));
}
do_timer(++ticks);
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 9ecfd3b547ba..42bd8ab955fa 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -221,6 +221,7 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
return 0;
}
+static __maybe_unused
int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
{
int ret = __cvdso_clock_getres_common(clock, res);