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: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 5 deletions

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 895337b16a24..3f4377e0aa04 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -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;