Techwizz/kernel-fxtec-pro1x
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thread_group_cputime: move a couple of callsites outside of ->siglock

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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>
This commit is contained in:
Oleg Nesterov 2008-11-17 15:40:08 +01:00 committed by Ingo Molnar
parent ce394471d1
commit 2b5fe6de58
2 changed files with 2 additions and 2 deletions
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2
kernel/exit.c
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@ -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,

2
kernel/sys.c
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@ -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);