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posix-timers: Make signal overrun accounting sensible

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The handling of the timer overrun in the signal code is inconsistent as it
takes previous overruns into account. This is just wrong as after the
reprogramming of a timer the overrun count starts over from a clean state,
i.e. 0.

Don't touch info::si_overrun in send_sigqueue() and only store the overrun
value at signal delivery time, which is computed from the timer itself
relative to the expiry time.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20241105064213.106738193@linutronix.de
This commit is contained in:
Thomas Gleixner 2024-11-05 09:14:32 +01:00
parent 513793bc6a
commit b06b0345ff
2 changed files with 6 additions and 11 deletions
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6
kernel/signal.c
View file

@ -1968,15 +1968,9 @@ int send_sigqueue(struct sigqueue *q, struct pid *pid, enum pid_type type, int s
ret = 0;
if (unlikely(!list_empty(&q->list))) {
/*
* If an SI_TIMER entry is already queue just increment
* the overrun count.
*/
q->info.si_overrun++;
result = TRACE_SIGNAL_ALREADY_PENDING;
goto out;
}
q->info.si_overrun = 0;
signalfd_notify(t, sig);
pending = (type != PIDTYPE_PID) ? &t->signal->shared_pending : &t->pending;

11
kernel/time/posix-timers.c
View file

@ -233,11 +233,12 @@ __initcall(init_posix_timers);
* The siginfo si_overrun field and the return value of timer_getoverrun(2)
* are of type int. Clamp the overrun value to INT_MAX
*/
static inline int timer_overrun_to_int(struct k_itimer *timr, int baseval)
static inline int timer_overrun_to_int(struct k_itimer *timr)
{
s64 sum = timr->it_overrun_last + (s64)baseval;
if (timr->it_overrun_last > (s64)INT_MAX)
return INT_MAX;
return sum > (s64)INT_MAX ? INT_MAX : (int)sum;
return (int)timr->it_overrun_last;
}
static void common_hrtimer_rearm(struct k_itimer *timr)
@ -280,7 +281,7 @@ bool posixtimer_deliver_signal(struct kernel_siginfo *info)
timr->it_overrun = -1LL;
++timr->it_signal_seq;
info->si_overrun = timer_overrun_to_int(timr, info->si_overrun);
info->si_overrun = timer_overrun_to_int(timr);
}
ret = true;
@ -774,7 +775,7 @@ SYSCALL_DEFINE1(timer_getoverrun, timer_t, timer_id)
if (!timr)
return -EINVAL;
overrun = timer_overrun_to_int(timr, 0);
overrun = timer_overrun_to_int(timr);
unlock_timer(timr, flags);
return overrun;