thread_group_cputime: move a couple of callsites outside of ->siglock

Impact: relax the locking of cpu-time accounting calls

->siglock buys nothing for thread_group_cputime() in do_sys_times() and
wait_task_zombie() (which btw takes the unrelated parent's ->siglock).

Actually I think do_sys_times() doesn't need ->siglock at all.

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

2 files changed, 2 insertions, 2 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index ae2b92be5fae..b9c4d8bb72e5 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1330,10 +1330,10 @@ static int wait_task_zombie(struct task_struct *p, int options,
                  * group, which consolidates times for all threads in the
                  * group including the group leader.
                  */
+                thread_group_cputime(p, &cputime);
                 spin_lock_irq(&p->parent->sighand->siglock);
                 psig = p->parent->signal;
                 sig = p->signal;
-                thread_group_cputime(p, &cputime);
                 psig->cutime =
                         cputime_add(psig->cutime,
                         cputime_add(cputime.utime,
diff --git a/kernel/sys.c b/kernel/sys.c
index 31deba8f7d16..5fc3a0cfb994 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -858,8 +858,8 @@ void do_sys_times(struct tms *tms)
         struct task_cputime cputime;
         cputime_t cutime, cstime;
 
-        spin_lock_irq(&current->sighand->siglock);
         thread_group_cputime(current, &cputime);
+        spin_lock_irq(&current->sighand->siglock);
         cutime = current->signal->cutime;
         cstime = current->signal->cstime;
         spin_unlock_irq(&current->sighand->siglock);