The patch titled
cpu-timers: change SIGEV_NONE timer implementation
has been added to the -mm tree. Its filename is
cpu-timers-change-sigev_none-timer-implementation.patch
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------------------------------------------------------
Subject: cpu-timers: change SIGEV_NONE timer implementation
From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
When user will setup timer without associated signal and process does not
use any other cpu timers and does not exit, tsk->signal->cputimer is
enabled and running forever, change that.
I used below program to check patch does not break current user space
visible behavior.
#include <sys/time.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <assert.h>
void consume_cpu(void)
{
int i = 0;
int count = 0;
for(i=0; i<100000000; i++)
count++;
}
int main(void)
{
int i;
struct sigaction act;
struct sigevent evt = { };
timer_t tid;
struct itimerspec spec = { };
evt.sigev_notify = SIGEV_NONE;
assert(timer_create(CLOCK_PROCESS_CPUTIME_ID, &evt, &tid) == 0);
spec.it_value.tv_sec = 10;
assert(timer_settime(tid, 0, &spec, NULL) == 0);
for (i = 0; i < 30; i++) {
consume_cpu();
memset(&spec, 0, sizeof(spec));
assert(timer_gettime(tid, &spec) == 0);
printf("%lu.%09lu\n",
(unsigned long) spec.it_value.tv_sec,
(unsigned long) spec.it_value.tv_nsec);
}
assert(timer_delete(tid) == 0);
return 0;
}
Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/posix-cpu-timers.c | 28 ++++++----------------------
1 file changed, 6 insertions(+), 22 deletions(-)
diff -puN kernel/posix-cpu-timers.c~cpu-timers-change-sigev_none-timer-implementation kernel/posix-cpu-timers.c
--- a/kernel/posix-cpu-timers.c~cpu-timers-change-sigev_none-timer-implementation
+++ a/kernel/posix-cpu-timers.c
@@ -614,7 +614,12 @@ static void arm_timer(struct k_itimer *t
*/
static void cpu_timer_fire(struct k_itimer *timer)
{
- if (unlikely(timer->sigq == NULL)) {
+ if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
+ /*
+ * User don't want any signal.
+ */
+ timer->it.cpu.expires.sched = 0;
+ } else if (unlikely(timer->sigq == NULL)) {
/*
* This a special case for clock_nanosleep,
* not a normal timer from sys_timer_create.
@@ -783,7 +788,6 @@ int posix_cpu_timer_set(struct k_itimer
*/
timer->it.cpu.expires = new_expires;
if (new_expires.sched != 0 &&
- (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
cpu_time_before(timer->it_clock, val, new_expires)) {
arm_timer(timer);
}
@@ -808,7 +812,6 @@ int posix_cpu_timer_set(struct k_itimer
timer->it_overrun = -1;
if (new_expires.sched != 0 &&
- (timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
!cpu_time_before(timer->it_clock, val, new_expires)) {
/*
* The designated time already passed, so we notify
@@ -882,25 +885,6 @@ void posix_cpu_timer_get(struct k_itimer
read_unlock(&tasklist_lock);
}
- if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
- if (timer->it.cpu.incr.sched == 0 &&
- cpu_time_before(timer->it_clock,
- timer->it.cpu.expires, now)) {
- /*
- * Do-nothing timer expired and has no reload,
- * so it's as if it was never set.
- */
- timer->it.cpu.expires.sched = 0;
- itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
- return;
- }
- /*
- * Account for any expirations and reloads that should
- * have happened.
- */
- bump_cpu_timer(timer, now);
- }
-
if (unlikely(clear_dead)) {
/*
* We've noticed that the thread is dead, but
_
Patches currently in -mm which might be from sgruszka@xxxxxxxxxx are
posix-cpu-timers-reset-expire-cache-when-no-timer-is-running.patch
cpu-timers-simplify-rlimit_cpu-handling.patch
cpu-timers-cleanup-arm_timer.patch
cpu-timers-return-correct-previous-timer-reload-value.patch
cpu-timers-change-sigev_none-timer-implementation.patch
cpu-timers-assure-to-not-iterate-over-all-threads-in-fastpath_timer_check.patch
cpu-timers-optimize-run_posix_cpu_timers.patch
--
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