use __set_task_state() for TRACED/STOPPED tasks

1. It is much easier to grep for ->state change if __set_task_state() is used
   instead of the direct assignment.

2. ptrace_stop() and handle_group_stop() use set_task_state() which adds the
   unneeded mb() (btw even if we use mb() it is still possible that do_wait()
   sees the new ->state but not ->exit_code, but this is ok).

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 6 deletions

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index b0d4ab4dfd3d..74730e0c1be1 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -53,7 +53,7 @@ void ptrace_untrace(struct task_struct *child)
         spin_lock(&child->sighand->siglock);
         if (task_is_traced(child)) {
                 if (child->signal->flags & SIGNAL_STOP_STOPPED) {
-                        child->state = TASK_STOPPED;
+                        __set_task_state(child, TASK_STOPPED);
                 } else {
                         signal_wake_up(child, 1);
                 }
@@ -103,18 +103,16 @@ int ptrace_check_attach(struct task_struct *child, int kill)
             && child->signal != NULL) {
                 ret = 0;
                 spin_lock_irq(&child->sighand->siglock);
-                if (task_is_stopped(child)) {
+                if (task_is_stopped(child))
                         child->state = TASK_TRACED;
-                } else if (!task_is_traced(child) && !kill) {
+                else if (!task_is_traced(child) && !kill)
                         ret = -ESRCH;
-                }
                 spin_unlock_irq(&child->sighand->siglock);
         }
         read_unlock(&tasklist_lock);
 
-        if (!ret && !kill) {
+        if (!ret && !kill)
                 wait_task_inactive(child);
-        }
 
         /* All systems go.. */
         return ret;