[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>

1 files changed, 8 insertions, 24 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 2dfaa5076c31..efba39626e66 100644
--- 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;
 }