From: claudio <claudio@openbsd.org>
Date: Sun, 13 Aug 2023 15:53:31 +0000 (+0000)
Subject: Fix P_WSLEEP handling when continuing SSTOP-ed processes
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=d4b9d4747036fa562b886f23a67e486ba94b3dc6;p=openbsd

Fix P_WSLEEP handling when continuing SSTOP-ed processes

When continuing a process on the sleep queue just let it switch to
p_stat = SSLEEP even when P_WSLEEP is set. Once a proc is SSTOP-ed
in sleep_finish() a valid sleep point has been reached and there is
no need to make the process runnable again (which results in some
hairy race conditions). Instead simply clear P_WSLEEP since a stopped
proc reached the sleep state and there is no race with wakeup() anymore.

OK mpi@
---

diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 098e199152d..eaa726642a0 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sig.c,v 1.311 2023/08/11 07:54:18 claudio Exp $	*/
+/*	$OpenBSD: kern_sig.c,v 1.312 2023/08/13 15:53:31 claudio Exp $	*/
 /*	$NetBSD: kern_sig.c,v 1.54 1996/04/22 01:38:32 christos Exp $	*/
 
 /*
@@ -1151,8 +1151,9 @@ ptsignal(struct proc *p, int signum, enum signal_type type)
 				atomic_clearbits_int(siglist, mask);
 			if (action == SIG_CATCH)
 				goto runfast;
-			if (p->p_wchan == NULL || p->p_flag & P_WSLEEP)
+			if (p->p_wchan == NULL)
 				goto run;
+			atomic_clearbits_int(&p->p_flag, P_WSLEEP);
 			p->p_stat = SSLEEP;
 			goto out;
 		}
@@ -2203,10 +2204,12 @@ single_thread_clear(struct proc *p, int flag)
 		 * it back into some sleep queue
 		 */
 		if (q->p_stat == SSTOP && (q->p_flag & flag) == 0) {
-			if (p->p_wchan == NULL || p->p_flag & P_WSLEEP)
+			if (q->p_wchan == NULL)
 				setrunnable(q);
-			else
+			else {
+				atomic_clearbits_int(&q->p_flag, P_WSLEEP);
 				q->p_stat = SSLEEP;
+			}
 		}
 	}
 	SCHED_UNLOCK(s);