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thread_group_cputime: kill the bogus ->signal != NULL check

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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: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Oleg Nesterov 2008-11-17 15:40:01 +01:00 committed by Ingo Molnar
parent 74fcd524e8
commit ce394471d1
1 changed files with 5 additions and 5 deletions
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10
kernel/posix-cpu-timers.c
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@ -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;