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Date: Tue, 4 Mar 2008 21:57:46 +0300
From: Oleg Nesterov <oleg@...sign.ru>
To: Andrew Morton <akpm@...ux-foundation.org>,
Roland McGrath <roland@...hat.com>
Cc: Jiri Kosina <jkosina@...e.cz>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] handle_stop_signal: unify partial/full stop handling
(on top of "[RFC,PATCH 1/2] signals: re-assign CLD_CONTINUED notification from the sender to reciever")
Now that handle_stop_signal() doesn't drop ->siglock, we can't see both
->group_stop_count && SIGNAL_STOP_STOPPED. Merge two "if" branches.
As Roland pointed out, we never actually needed 2 do_notify_parent_cldstop()
calls.
Signed-off-by: Oleg Nesterov <oleg@...sign.ru>
--- 25/kernel/signal.c~2_HSS_SIMPLIFY 2008-03-03 17:06:53.000000000 +0300
+++ 25/kernel/signal.c 2008-03-03 17:08:31.000000000 +0300
@@ -578,33 +578,16 @@ static void handle_stop_signal(int sig,
t = next_thread(t);
} while (t != p);
} else if (sig == SIGCONT) {
+ unsigned int why;
/*
* Remove all stop signals from all queues,
* and wake all threads.
*/
- if (unlikely(p->signal->group_stop_count > 0)) {
- /*
- * There was a group stop in progress. We'll
- * pretend it finished before we got here. We are
- * obliged to report it to the parent: if the
- * SIGSTOP happened "after" this SIGCONT, then it
- * would have cleared this pending SIGCONT. If it
- * happened "before" this SIGCONT, then the parent
- * got the SIGCHLD about the stop finishing before
- * the continue happened. We do the notification
- * now, and it's as if the stop had finished and
- * the SIGCHLD was pending on entry to this kill.
- */
- p->signal->group_stop_count = 0;
- p->signal->flags = SIGNAL_STOP_CONTINUED |
- SIGNAL_CLD_STOPPED;
- }
rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
t = p;
do {
unsigned int state;
rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
-
/*
* If there is a handler for SIGCONT, we must make
* sure that no thread returns to user mode before
@@ -614,7 +597,7 @@ static void handle_stop_signal(int sig,
* running the handler. With the TIF_SIGPENDING
* flag set, the thread will pause and acquire the
* siglock that we hold now and until we've queued
- * the pending signal.
+ * the pending signal.
*
* Wake up the stopped thread _after_ setting
* TIF_SIGPENDING
@@ -629,13 +612,23 @@ static void handle_stop_signal(int sig,
t = next_thread(t);
} while (t != p);
- if (p->signal->flags & SIGNAL_STOP_STOPPED) {
- /*
- * We were in fact stopped, and are now continued.
- * Notify the parent with CLD_CONTINUED.
- */
- p->signal->flags = SIGNAL_STOP_CONTINUED |
- SIGNAL_CLD_CONTINUED;
+ /*
+ * Notify the parent with CLD_CONTINUED if we were stopped.
+ *
+ * If we were in the middle of a group stop, we pretend it
+ * was already finished, and then continued. Since SIGCHLD
+ * doesn't queue we report only CLD_STOPPED, as if the next
+ * CLD_CONTINUED was dropped.
+ */
+ why = 0;
+ if (p->signal->flags & SIGNAL_STOP_STOPPED)
+ why |= SIGNAL_CLD_CONTINUED;
+ else if (p->signal->group_stop_count)
+ why |= SIGNAL_CLD_STOPPED;
+
+ if (why) {
+ p->signal->flags = why | SIGNAL_STOP_CONTINUED;
+ p->signal->group_stop_count = 0;
p->signal->group_exit_code = 0;
} else {
/*
--
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