do_signal_stop() does not need tasklist_lock anymore.
So it does not need to do misc re-checks, and we can
simplify the code.
Signed-off-by: Oleg Nesterov <[email protected]>
--- 2.6.16-rc3/kernel/signal.c~3_DOSS 2006-02-23 01:22:45.000000000 +0300
+++ 2.6.16-rc3/kernel/signal.c 2006-02-23 01:46:17.000000000 +0300
@@ -1685,8 +1685,7 @@ out:
* Returns nonzero if we've actually stopped and released the siglock.
* Returns zero if we didn't stop and still hold the siglock.
*/
-static int
-do_signal_stop(int signr)
+static int do_signal_stop(int signr)
{
struct signal_struct *sig = current->signal;
struct sighand_struct *sighand = current->sighand;
@@ -1706,7 +1705,6 @@ do_signal_stop(int signr)
set_current_state(TASK_STOPPED);
if (stop_count == 0)
sig->flags = SIGNAL_STOP_STOPPED;
- spin_unlock_irq(&sighand->siglock);
}
else if (thread_group_empty(current)) {
/*
@@ -1715,71 +1713,38 @@ do_signal_stop(int signr)
current->exit_code = current->signal->group_exit_code = signr;
set_current_state(TASK_STOPPED);
sig->flags = SIGNAL_STOP_STOPPED;
- spin_unlock_irq(&sighand->siglock);
}
else {
/*
+ * (sig->group_stop_count == 0)
* There is no group stop already in progress.
- * We must initiate one now, but that requires
- * dropping siglock to get both the tasklist lock
- * and siglock again in the proper order. Note that
- * this allows an intervening SIGCONT to be posted.
- * We need to check for that and bail out if necessary.
+ * We must initiate one now.
*/
struct task_struct *t;
- spin_unlock_irq(&sighand->siglock);
-
- /* signals can be posted during this window */
-
- read_lock(&tasklist_lock);
- spin_lock_irq(&sighand->siglock);
+ current->exit_code = signr;
+ sig->group_exit_code = signr;
- if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) {
+ stop_count = 0;
+ for (t = next_thread(current); t != current; t = next_thread(t))
/*
- * Another stop or continue happened while we
- * didn't have the lock. We can just swallow this
- * signal now. If we raced with a SIGCONT, that
- * should have just cleared it now. If we raced
- * with another processor delivering a stop signal,
- * then the SIGCONT that wakes us up should clear it.
+ * Setting state to TASK_STOPPED for a group
+ * stop is always done with the siglock held,
+ * so this check has no races.
*/
- read_unlock(&tasklist_lock);
- return 0;
- }
-
- if (sig->group_stop_count == 0) {
- sig->group_exit_code = signr;
- stop_count = 0;
- for (t = next_thread(current); t != current;
- t = next_thread(t))
- /*
- * Setting state to TASK_STOPPED for a group
- * stop is always done with the siglock held,
- * so this check has no races.
- */
- if (!t->exit_state &&
- !(t->state & (TASK_STOPPED|TASK_TRACED))) {
- stop_count++;
- signal_wake_up(t, 0);
- }
- sig->group_stop_count = stop_count;
- }
- else {
- /* A race with another thread while unlocked. */
- signr = sig->group_exit_code;
- stop_count = --sig->group_stop_count;
- }
+ if (!t->exit_state &&
+ !(t->state & (TASK_STOPPED|TASK_TRACED))) {
+ stop_count++;
+ signal_wake_up(t, 0);
+ }
+ sig->group_stop_count = stop_count;
- current->exit_code = signr;
set_current_state(TASK_STOPPED);
if (stop_count == 0)
sig->flags = SIGNAL_STOP_STOPPED;
-
- spin_unlock_irq(&sighand->siglock);
- read_unlock(&tasklist_lock);
}
+ spin_unlock_irq(&sighand->siglock);
finish_stop(stop_count);
return 1;
}
-
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