• S
    cpu-timers: Change SIGEV_NONE timer implementation · 1f169f84
    Stanislaw Gruszka 提交于
    When user sets up a 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.
    
    Avoid running the timer for no reason.
    
    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: NStanislaw 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: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
    1f169f84
posix-cpu-timers.c 43.3 KB