[PATCH] sys_times: don't take tasklist_lock

sys_times: don't take tasklist_lock

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 12 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index 84371fdc660b..7ef7f6054c28 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1206,7 +1206,7 @@ asmlinkage long sys_times(struct tms __user * tbuf)
                 struct task_struct *t;
                 cputime_t utime, stime, cutime, cstime;
 
-                read_lock(&tasklist_lock);
+                spin_lock_irq(&tsk->sighand->siglock);
                 utime = tsk->signal->utime;
                 stime = tsk->signal->stime;
                 t = tsk;
@@ -1216,20 +1216,9 @@ asmlinkage long sys_times(struct tms __user * tbuf)
                         t = next_thread(t);
                 } while (t != tsk);
 
-                /*
-                 * While we have tasklist_lock read-locked, no dying thread
-                 * can be updating current->signal->[us]time.  Instead,
-                 * we got their counts included in the live thread loop.
-                 * However, another thread can come in right now and
-                 * do a wait call that updates current->signal->c[us]time.
-                 * To make sure we always see that pair updated atomically,
-                 * we take the siglock around fetching them.
-                 */
-                spin_lock_irq(&tsk->sighand->siglock);
                 cutime = tsk->signal->cutime;
                 cstime = tsk->signal->cstime;
                 spin_unlock_irq(&tsk->sighand->siglock);
-                read_unlock(&tasklist_lock);
 
                 tmp.tms_utime = cputime_to_clock_t(utime);
                 tmp.tms_stime = cputime_to_clock_t(stime);