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authorLennart Poettering <lennart@poettering.net>2017-06-22 21:04:20 +0200
committerLennart Poettering <lennart@poettering.net>2017-06-22 21:04:20 +0200
commitc54be90b28cc25663ff52c505956fa3de0bea1fb (patch)
tree91bef508dfd8a78137dcf87ba6028ad1a15ede0e /src/core/timer.c
parent79fc8b9623354a98ca81b4d35e576e9c9e3bf687 (diff)
downloadsystemd-c54be90b28cc25663ff52c505956fa3de0bea1fb.tar.gz
timer: make sure we use the right monotonic timestamp
This reworks timer_enter_waiting() in a couple of ways in order to clean it up a bit and fix #5629. Most importantly, we previously we initialized ts_monotonic to either the current time in CLOCK_MONOTONIC or in CLOCK_BOOTTIME, depending on t->wake_system. Then given specific conditions we'd use this time as base for our timers. And afterwards, if t->wake_system was on we'd convetr the resulting value from CLOCK_MONOTONIC to CLOCK_BOOTTIME again — which of course is wrong since we already were in CLOCK_BOOTTIME! This fixes this logic, by using a triple timestamp so that we always have the right base around, and initially only calculate in CLOCK_MONOTONIC and only convert as last step. Conversion between the clocks is now done with the generic usec_shift_clock(), and additions via usec_add() making these calculations a bit safer. Fixes: #5629
Diffstat (limited to 'src/core/timer.c')
-rw-r--r--src/core/timer.c41
1 files changed, 11 insertions, 30 deletions
diff --git a/src/core/timer.c b/src/core/timer.c
index af67b7591a..701949fd60 100644
--- a/src/core/timer.c
+++ b/src/core/timer.c
@@ -316,21 +316,6 @@ static void timer_enter_elapsed(Timer *t, bool leave_around) {
timer_enter_dead(t, TIMER_SUCCESS);
}
-static usec_t monotonic_to_boottime(usec_t t) {
- usec_t a, b;
-
- if (t <= 0)
- return 0;
-
- a = now(clock_boottime_or_monotonic());
- b = now(CLOCK_MONOTONIC);
-
- if (t + a > b)
- return t + a - b;
- else
- return 0;
-}
-
static void add_random(Timer *t, usec_t *v) {
char s[FORMAT_TIMESPAN_MAX];
usec_t add;
@@ -355,9 +340,9 @@ static void add_random(Timer *t, usec_t *v) {
static void timer_enter_waiting(Timer *t, bool initial) {
bool found_monotonic = false, found_realtime = false;
- usec_t ts_realtime, ts_monotonic;
- usec_t base = 0;
bool leave_around = false;
+ triple_timestamp ts;
+ usec_t base = 0;
TimerValue *v;
Unit *trigger;
int r;
@@ -371,11 +356,7 @@ static void timer_enter_waiting(Timer *t, bool initial) {
return;
}
- /* If we shall wake the system we use the boottime clock
- * rather than the monotonic clock. */
-
- ts_realtime = now(CLOCK_REALTIME);
- ts_monotonic = now(t->wake_system ? clock_boottime_or_monotonic() : CLOCK_MONOTONIC);
+ triple_timestamp_get(&ts);
t->next_elapse_monotonic_or_boottime = t->next_elapse_realtime = 0;
LIST_FOREACH(value, v, t->values) {
@@ -391,7 +372,7 @@ static void timer_enter_waiting(Timer *t, bool initial) {
* to that. If we don't just start from
* now. */
- b = t->last_trigger.realtime > 0 ? t->last_trigger.realtime : ts_realtime;
+ b = t->last_trigger.realtime > 0 ? t->last_trigger.realtime : ts.realtime;
r = calendar_spec_next_usec(v->calendar_spec, b, &v->next_elapse);
if (r < 0)
@@ -405,13 +386,14 @@ static void timer_enter_waiting(Timer *t, bool initial) {
found_realtime = true;
} else {
+
switch (v->base) {
case TIMER_ACTIVE:
if (state_translation_table[t->state] == UNIT_ACTIVE)
base = UNIT(t)->inactive_exit_timestamp.monotonic;
else
- base = ts_monotonic;
+ base = ts.monotonic;
break;
case TIMER_BOOT:
@@ -456,12 +438,11 @@ static void timer_enter_waiting(Timer *t, bool initial) {
assert_not_reached("Unknown timer base");
}
- if (t->wake_system)
- base = monotonic_to_boottime(base);
-
- v->next_elapse = base + v->value;
+ v->next_elapse = usec_add(usec_shift_clock(base, CLOCK_MONOTONIC, TIMER_MONOTONIC_CLOCK(t)), v->value);
- if (!initial && v->next_elapse < ts_monotonic && IN_SET(v->base, TIMER_ACTIVE, TIMER_BOOT, TIMER_STARTUP)) {
+ if (!initial &&
+ v->next_elapse < triple_timestamp_by_clock(&ts, TIMER_MONOTONIC_CLOCK(t)) &&
+ IN_SET(v->base, TIMER_ACTIVE, TIMER_BOOT, TIMER_STARTUP)) {
/* This is a one time trigger, disable it now */
v->disabled = true;
continue;
@@ -488,7 +469,7 @@ static void timer_enter_waiting(Timer *t, bool initial) {
add_random(t, &t->next_elapse_monotonic_or_boottime);
- left = t->next_elapse_monotonic_or_boottime > ts_monotonic ? t->next_elapse_monotonic_or_boottime - ts_monotonic : 0;
+ left = usec_sub_unsigned(t->next_elapse_monotonic_or_boottime, triple_timestamp_by_clock(&ts, TIMER_MONOTONIC_CLOCK(t)));
log_unit_debug(UNIT(t), "Monotonic timer elapses in %s.", format_timespan(buf, sizeof(buf), left, 0));
if (t->monotonic_event_source) {