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Commit ae1a78ee authored by Stanislaw Gruszka's avatar Stanislaw Gruszka Committed by Thomas Gleixner
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cpu-timers: Return correct previous timer reload value 



According POSIX we need to correctly set old timer it_interval value when
user request that in timer_settime().  Tested using below program.

 #include <sys/time.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
 #include <unistd.h>
 #include <assert.h>

 int main(void)
 {
	struct sigaction act;
	struct sigevent evt = { };
	timer_t tid;
	struct itimerspec spec, u_spec, k_spec;

	evt.sigev_notify = SIGEV_SIGNAL;
	evt.sigev_signo = SIGPROF;
	assert(timer_create(CLOCK_PROCESS_CPUTIME_ID, &evt,  &tid) == 0);

	spec.it_value.tv_sec = 1;
	spec.it_value.tv_nsec = 2;
	spec.it_interval.tv_sec = 3;
	spec.it_interval.tv_nsec = 4;
	u_spec = spec;
	assert(timer_settime(tid, 0, &spec,  NULL) == 0);

	spec.it_value.tv_sec = 5;
	spec.it_value.tv_nsec = 6;
	spec.it_interval.tv_sec = 7;
	spec.it_interval.tv_nsec = 8;
	assert(timer_settime(tid, 0, &spec,  &k_spec) == 0);

 #define PRT(val) printf(#val ":\t%d/%d\n", (int) u_spec.val, (int) k_spec.val)
	PRT(it_value.tv_sec);
	PRT(it_value.tv_nsec);
	PRT(it_interval.tv_sec);
	PRT(it_interval.tv_nsec);

	return 0;
 }

Signed-off-by: default avatarStanislaw Gruszka <sgruszka@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 5eb9aa64

kernel/posix-cpu-timers.c

+3 −2
Original line number Diff line number Diff line
@@ -676,7 +676,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags, 
			struct itimerspec *new, struct itimerspec *old)

{

	struct task_struct *p = timer->it.cpu.task;

	union cpu_time_count old_expires, new_expires, val;

	union cpu_time_count old_expires, new_expires, old_incr, val;

	int ret;



	if (unlikely(p == NULL)) {
@@ -707,6 +707,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags, 
	BUG_ON(!irqs_disabled());



	ret = 0;

	old_incr = timer->it.cpu.incr;

	spin_lock(&p->sighand->siglock);

	old_expires = timer->it.cpu.expires;

	if (unlikely(timer->it.cpu.firing)) {
@@ -822,7 +823,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags, 
 out:

	if (old) {

		sample_to_timespec(timer->it_clock,

				   timer->it.cpu.incr, &old->it_interval);

				   old_incr, &old->it_interval);

	}

	return ret;

}