Commit f55db609 authored by Stanislaw Gruszka's avatar Stanislaw Gruszka Committed by Thomas Gleixner
Browse files

cpu-timers: Simplify RLIMIT_CPU handling 

Let always set signal->cputime_expires expiration cache when setting
new itimer, POSIX 1.b timer, and RLIMIT_CPU.  Since we are
initializing prof_exp expiration cache during fork(), this allows to
remove "RLIMIT_CPU != inf" check from fastpath_timer_check() and do
some other cleanups.

Checked against regression using test cases from:
http://marc.info/?l=linux-kernel&m=123749066504641&w=4
http://marc.info/?l=linux-kernel&m=123811277916642&w=2



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 522dba71

kernel/posix-cpu-timers.c

+27 −48
Original line number Diff line number Diff line
@@ -11,20 +11,19 @@ 
#include <trace/events/timer.h>



/*

 * Called after updating RLIMIT_CPU to set timer expiration if necessary.

 * Called after updating RLIMIT_CPU to run cpu timer and update

 * tsk->signal->cputime_expires expiration cache if necessary. Needs

 * siglock protection since other code may update expiration cache as

 * well.

 */

void update_rlimit_cpu(unsigned long rlim_new)

{

	cputime_t cputime = secs_to_cputime(rlim_new);

	struct signal_struct *const sig = current->signal;



	if (cputime_eq(sig->it[CPUCLOCK_PROF].expires, cputime_zero) ||

	    cputime_gt(sig->it[CPUCLOCK_PROF].expires, cputime)) {

	spin_lock_irq(&current->sighand->siglock);

	set_process_cpu_timer(current, CPUCLOCK_PROF, &cputime, NULL);

	spin_unlock_irq(&current->sighand->siglock);

}

}



static int check_clock(const clockid_t which_clock)

{
@@ -564,7 +563,6 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now) 
	struct list_head *head, *listpos;

	struct cpu_timer_list *const nt = &timer->it.cpu;

	struct cpu_timer_list *next;

	unsigned long i;



	head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?

		p->cpu_timers : p->signal->cpu_timers);
@@ -630,19 +628,10 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now) 
			default:

				BUG();

			case CPUCLOCK_VIRT:

				if (expires_le(sig->it[CPUCLOCK_VIRT].expires,

					       exp->cpu))

					break;

				if (expires_gt(sig->cputime_expires.virt_exp, exp->cpu))

					sig->cputime_expires.virt_exp = exp->cpu;

				break;

			case CPUCLOCK_PROF:

				if (expires_le(sig->it[CPUCLOCK_PROF].expires,

					       exp->cpu))

					break;

				i = sig->rlim[RLIMIT_CPU].rlim_cur;

				if (i != RLIM_INFINITY &&

				    i <= cputime_to_secs(exp->cpu))

					break;

				if (expires_gt(sig->cputime_expires.prof_exp, exp->cpu))

					sig->cputime_expires.prof_exp = exp->cpu;

				break;

			case CPUCLOCK_SCHED:
@@ -1386,7 +1375,7 @@ static inline int fastpath_timer_check(struct task_struct *tsk) 
			return 1;

	}



	return sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY;

	return 0;

}



/*
@@ -1452,21 +1441,23 @@ void run_posix_cpu_timers(struct task_struct *tsk) 
}



/*

 * Set one of the process-wide special case CPU timers.

 * Set one of the process-wide special case CPU timers or RLIMIT_CPU.

 * The tsk->sighand->siglock must be held by the caller.

 * The *newval argument is relative and we update it to be absolute, *oldval

 * is absolute and we update it to be relative.

 */

void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,

			   cputime_t *newval, cputime_t *oldval)

{

	union cpu_time_count now;

	struct list_head *head;



	BUG_ON(clock_idx == CPUCLOCK_SCHED);

	cpu_timer_sample_group(clock_idx, tsk, &now);



	if (oldval) {

		/*

		 * We are setting itimer. The *oldval is absolute and we update

		 * it to be relative, *newval argument is relative and we update

		 * it to be absolute.

		 */

		if (!cputime_eq(*oldval, cputime_zero)) {

			if (cputime_le(*oldval, now.cpu)) {

				/* Just about to fire. */
@@ -1479,35 +1470,23 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, 
		if (cputime_eq(*newval, cputime_zero))

			return;

		*newval = cputime_add(*newval, now.cpu);



		/*

		 * If the RLIMIT_CPU timer will expire before the

		 * ITIMER_PROF timer, we have nothing else to do.

		 */

		if (tsk->signal->rlim[RLIMIT_CPU].rlim_cur

		    < cputime_to_secs(*newval))

			return;

	}



	/*

	 * Check whether there are any process timers already set to fire

	 * before this one.  If so, we don't have anything more to do.

	 * Update expiration cache if we are the earliest timer, or eventually

	 * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.

	 */

	head = &tsk->signal->cpu_timers[clock_idx];

	if (list_empty(head) ||

	    cputime_ge(list_first_entry(head,

				  struct cpu_timer_list, entry)->expires.cpu,

		       *newval)) {

	switch (clock_idx) {

	case CPUCLOCK_PROF:

		if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))

			tsk->signal->cputime_expires.prof_exp = *newval;

		break;

	case CPUCLOCK_VIRT:

		if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))

			tsk->signal->cputime_expires.virt_exp = *newval;

		break;

	}

}

}



static int do_cpu_nanosleep(const clockid_t which_clock, int flags,

			    struct timespec *rqtp, struct itimerspec *it)

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