Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'timers-urgent-2021-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Thomas Gleixner:
"A small set of timer related fixes:
- Plug a race between rearm and process tick in the posix CPU timers
code
- Make the optimization to avoid recalculation of the next timer
interrupt work correctly when there are no timers pending"
* tag 'timers-urgent-2021-07-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timers: Fix get_next_timer_interrupt() with no timers pending
posix-cpu-timers: Fix rearm racing against process tick
+10
-8
+5
-5
kernel/time/posix-cpu-timers.c
+5
-5
kernel/time/posix-cpu-timers.c
···
991
991
if (!p)
992
992
goto out;
993
993
994
+
/* Protect timer list r/w in arm_timer() */
995
+
sighand = lock_task_sighand(p, &flags);
996
+
if (unlikely(sighand == NULL))
997
+
goto out;
998
+
994
999
/*
995
1000
* Fetch the current sample and update the timer's expiry time.
996
1001
*/
···
1005
1000
now = cpu_clock_sample_group(clkid, p, true);
1006
1001
1007
1002
bump_cpu_timer(timer, now);
1008
-
1009
-
/* Protect timer list r/w in arm_timer() */
1010
-
sighand = lock_task_sighand(p, &flags);
1011
-
if (unlikely(sighand == NULL))
1012
-
goto out;
1013
1003
1014
1004
/*
1015
1005
* Now re-arm for the new expiry time.
+5
-3
kernel/time/timer.c
+5
-3
kernel/time/timer.c
···
207
207
unsigned int cpu;
208
208
bool next_expiry_recalc;
209
209
bool is_idle;
210
+
bool timers_pending;
210
211
DECLARE_BITMAP(pending_map, WHEEL_SIZE);
211
212
struct hlist_head vectors[WHEEL_SIZE];
212
213
} ____cacheline_aligned;
···
596
595
* can reevaluate the wheel:
597
596
*/
598
597
base->next_expiry = bucket_expiry;
598
+
base->timers_pending = true;
599
599
base->next_expiry_recalc = false;
600
600
trigger_dyntick_cpu(base, timer);
601
601
}
···
1584
1582
}
1585
1583
1586
1584
base->next_expiry_recalc = false;
1585
+
base->timers_pending = !(next == base->clk + NEXT_TIMER_MAX_DELTA);
1587
1586
1588
1587
return next;
1589
1588
}
···
1636
1633
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]);
1637
1634
u64 expires = KTIME_MAX;
1638
1635
unsigned long nextevt;
1639
-
bool is_max_delta;
1640
1636
1641
1637
/*
1642
1638
* Pretend that there is no timer pending if the cpu is offline.
···
1648
1646
if (base->next_expiry_recalc)
1649
1647
base->next_expiry = __next_timer_interrupt(base);
1650
1648
nextevt = base->next_expiry;
1651
-
is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA);
1652
1649
1653
1650
/*
1654
1651
* We have a fresh next event. Check whether we can forward the
···
1665
1664
expires = basem;
1666
1665
base->is_idle = false;
1667
1666
} else {
1668
-
if (!is_max_delta)
1667
+
if (base->timers_pending)
1669
1668
expires = basem + (u64)(nextevt - basej) * TICK_NSEC;
1670
1669
/*
1671
1670
* If we expect to sleep more than a tick, mark the base idle.
···
1948
1947
base = per_cpu_ptr(&timer_bases[b], cpu);
1949
1948
base->clk = jiffies;
1950
1949
base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA;
1950
+
base->timers_pending = false;
1951
1951
base->is_idle = false;
1952
1952
}
1953
1953
return 0;