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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-08 16:58:07 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-08 16:58:07 +0000
commit5a6d13c86f2fe6304450e907fc1d8d72da82efef (patch)
tree1bd4e8854203c575eabaa99e2c509f8886065733 /kernel/time
parentAdding upstream version 6.1.76. (diff)
downloadlinux-upstream/6.1.82.tar.xz
linux-upstream/6.1.82.zip
Adding upstream version 6.1.82.upstream/6.1.82upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/clocksource.c25
-rw-r--r--kernel/time/hrtimer.c17
2 files changed, 38 insertions, 4 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) {
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 5561dabc9..9bb88836c 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -1082,6 +1082,7 @@ static int enqueue_hrtimer(struct hrtimer *timer,
enum hrtimer_mode mode)
{
debug_activate(timer, mode);
+ WARN_ON_ONCE(!base->cpu_base->online);
base->cpu_base->active_bases |= 1 << base->index;
@@ -2180,6 +2181,7 @@ int hrtimers_prepare_cpu(unsigned int cpu)
cpu_base->softirq_next_timer = NULL;
cpu_base->expires_next = KTIME_MAX;
cpu_base->softirq_expires_next = KTIME_MAX;
+ cpu_base->online = 1;
hrtimer_cpu_base_init_expiry_lock(cpu_base);
return 0;
}
@@ -2247,6 +2249,7 @@ int hrtimers_cpu_dying(unsigned int dying_cpu)
smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);
raw_spin_unlock(&new_base->lock);
+ old_base->online = 0;
raw_spin_unlock(&old_base->lock);
return 0;
@@ -2263,7 +2266,7 @@ void __init hrtimers_init(void)
/**
* schedule_hrtimeout_range_clock - sleep until timeout
* @expires: timeout value (ktime_t)
- * @delta: slack in expires timeout (ktime_t)
+ * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
* @mode: timer mode
* @clock_id: timer clock to be used
*/
@@ -2290,6 +2293,13 @@ schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
return -EINTR;
}
+ /*
+ * Override any slack passed by the user if under
+ * rt contraints.
+ */
+ if (rt_task(current))
+ delta = 0;
+
hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
hrtimer_sleeper_start_expires(&t, mode);
@@ -2309,7 +2319,7 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
/**
* schedule_hrtimeout_range - sleep until timeout
* @expires: timeout value (ktime_t)
- * @delta: slack in expires timeout (ktime_t)
+ * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
* @mode: timer mode
*
* Make the current task sleep until the given expiry time has
@@ -2317,7 +2327,8 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
* the current task state has been set (see set_current_state()).
*
* The @delta argument gives the kernel the freedom to schedule the
- * actual wakeup to a time that is both power and performance friendly.
+ * actual wakeup to a time that is both power and performance friendly
+ * for regular (non RT/DL) tasks.
* The kernel give the normal best effort behavior for "@expires+@delta",
* but may decide to fire the timer earlier, but no earlier than @expires.
*