Commit b06b0345 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

posix-timers: Make signal overrun accounting sensible 



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: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20241105064213.106738193@linutronix.de
parent 513793bc

kernel/signal.c

+0 −6
Original line number Diff line number Diff line
@@ -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;

kernel/time/posix-timers.c

+6 −5
Original line number Diff line number Diff line
@@ -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;