[PATCH] simplify do_signal_stop()

do_signal_stop() considers 'thread_group_empty()' as a special case.
This was needed to avoid taking tasklist_lock. Since this lock is
unneeded any longer, we can remove this special case and simplify
the code even more.

Also, before this patch, finish_stop() was called with stop_count == -1
for 'thread_group_empty()' case. This is not strictly wrong, but confusing
and unneeded.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/signal.c b/kernel/signal.c
index 2dfaa50..efba396 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1685,8 +1685,7 @@ out:
 static int do_signal_stop(int signr)
 {
        struct signal_struct *sig = current->signal;
-       struct sighand_struct *sighand = current->sighand;
-       int stop_count = -1;
+       int stop_count;
 
        if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED))
                return 0;
@@ -1696,30 +1695,14 @@ static int do_signal_stop(int signr)
                 * There is a group stop in progress.  We don't need to
                 * start another one.
                 */
-               signr = sig->group_exit_code;
                stop_count = --sig->group_stop_count;
-               current->exit_code = signr;
-               set_current_state(TASK_STOPPED);
-               if (stop_count == 0)
-                       sig->flags = SIGNAL_STOP_STOPPED;
-       }
-       else if (thread_group_empty(current)) {
-               /*
-                * Lock must be held through transition to stopped state.
-                */
-               current->exit_code = current->signal->group_exit_code = signr;
-               set_current_state(TASK_STOPPED);
-               sig->flags = SIGNAL_STOP_STOPPED;
-       }
-       else {
+       } else {
                /*
-                * (sig->group_stop_count == 0)
                 * There is no group stop already in progress.
                 * We must initiate one now.
                 */
                struct task_struct *t;
 
-               current->exit_code = signr;
                sig->group_exit_code = signr;
 
                stop_count = 0;
@@ -1735,13 +1718,14 @@ static int do_signal_stop(int signr)
                                signal_wake_up(t, 0);
                        }
                sig->group_stop_count = stop_count;
-
-               set_current_state(TASK_STOPPED);
-               if (stop_count == 0)
-                       sig->flags = SIGNAL_STOP_STOPPED;
        }
 
-       spin_unlock_irq(&sighand->siglock);
+       if (stop_count == 0)
+               sig->flags = SIGNAL_STOP_STOPPED;
+       current->exit_code = sig->group_exit_code;
+       __set_current_state(TASK_STOPPED);
+
+       spin_unlock_irq(&current->sighand->siglock);
        finish_stop(stop_count);
        return 1;
 }