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-rw-r--r--kernel/time/clocksource.c25
1 files changed, 24 insertions, 1 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 1c90e710d..cc6db3bce 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -126,6 +126,7 @@ static DECLARE_WORK(watchdog_work, clocksource_watchdog_work);
static DEFINE_SPINLOCK(watchdog_lock);
static int watchdog_running;
static atomic_t watchdog_reset_pending;
+static int64_t watchdog_max_interval;
static inline void clocksource_watchdog_lock(unsigned long *flags)
{
@@ -144,6 +145,7 @@ static void __clocksource_change_rating(struct clocksource *cs, int rating);
* Interval: 0.5sec.
*/
#define WATCHDOG_INTERVAL (HZ >> 1)
+#define WATCHDOG_INTERVAL_MAX_NS ((2 * WATCHDOG_INTERVAL) * (NSEC_PER_SEC / HZ))
static void clocksource_watchdog_work(struct work_struct *work)
{
@@ -396,8 +398,8 @@ static inline void clocksource_reset_watchdog(void)
static void clocksource_watchdog(struct timer_list *unused)
{
u64 csnow, wdnow, cslast, wdlast, delta;
+ int64_t wd_nsec, cs_nsec, interval;
int next_cpu, reset_pending;
- int64_t wd_nsec, cs_nsec;
struct clocksource *cs;
enum wd_read_status read_ret;
unsigned long extra_wait = 0;
@@ -467,6 +469,27 @@ static void clocksource_watchdog(struct timer_list *unused)
if (atomic_read(&watchdog_reset_pending))
continue;
+ /*
+ * The processing of timer softirqs can get delayed (usually
+ * on account of ksoftirqd not getting to run in a timely
+ * manner), which causes the watchdog interval to stretch.
+ * Skew detection may fail for longer watchdog intervals
+ * on account of fixed margins being used.
+ * Some clocksources, e.g. acpi_pm, cannot tolerate
+ * watchdog intervals longer than a few seconds.
+ */
+ interval = max(cs_nsec, wd_nsec);
+ if (unlikely(interval > WATCHDOG_INTERVAL_MAX_NS)) {
+ if (system_state > SYSTEM_SCHEDULING &&
+ interval > 2 * watchdog_max_interval) {
+ watchdog_max_interval = interval;
+ pr_warn("Long readout interval, skipping watchdog check: cs_nsec: %lld wd_nsec: %lld\n",
+ cs_nsec, wd_nsec);
+ }
+ watchdog_timer.expires = jiffies;
+ continue;
+ }
+
/* Check the deviation from the watchdog clocksource. */
md = cs->uncertainty_margin + watchdog->uncertainty_margin;
if (abs(cs_nsec - wd_nsec) > md) {