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Commit ce394471 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Ingo Molnar
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thread_group_cputime: kill the bogus ->signal != NULL check 



Impact: simplify the code

thread_group_cputime() is called by current when it must have the valid
->signal, or under ->siglock, or under tasklist_lock after the ->signal
check, or the caller is wait_task_zombie() which reaps the child. In any
case ->signal can't be NULL.

But the point of this patch is not optimization. If it is possible to call
thread_group_cputime() when ->signal == NULL we are doing something wrong,
and we should not mask the problem. thread_group_cputime() fills *times
and the caller will use it, if we silently use task_struct->*times* we
report the wrong values.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 74fcd524

kernel/posix-cpu-timers.c

+5 −5
Original line number Diff line number Diff line
@@ -58,21 +58,21 @@ void thread_group_cputime( 
	struct task_struct *tsk,

	struct task_cputime *times)

{

	struct signal_struct *sig;

	struct task_cputime *totals, *tot;

	int i;

	struct task_cputime *tot;



	sig = tsk->signal;

	if (unlikely(!sig) || !sig->cputime.totals) {

	totals = tsk->signal->cputime.totals;

	if (!totals) {

		times->utime = tsk->utime;

		times->stime = tsk->stime;

		times->sum_exec_runtime = tsk->se.sum_exec_runtime;

		return;

	}



	times->stime = times->utime = cputime_zero;

	times->sum_exec_runtime = 0;

	for_each_possible_cpu(i) {

		tot = per_cpu_ptr(tsk->signal->cputime.totals, i);

		tot = per_cpu_ptr(totals, i);

		times->utime = cputime_add(times->utime, tot->utime);

		times->stime = cputime_add(times->stime, tot->stime);

		times->sum_exec_runtime += tot->sum_exec_runtime;