Indicate that a process has stopped by setting PS_STOPPED flag

The checks in dowait6 and orphanpg using ps_mainproc are flawed and
fail if the mainproc called pthread_exit before the other threads.
Adding the flag in proc_stop_sweep is racy but the best we have right now.
This fixes regress/sys/kern/signal/sig-stop3.

OK mpi@

4 files changed, 14 insertions, 15 deletions

diff --git a/sys/kern/kern_exit.c b/sys/kern/kern_exit.c
index 5dee520ef44..d5dd1f387b7 100644
--- a/sys/kern/kern_exit.c
+++ b/sys/kern/kern_exit.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_exit.c,v 1.238 2024/10/15 11:54:07 claudio Exp $	*/
+/*	$OpenBSD: kern_exit.c,v 1.239 2024/10/15 13:49:26 claudio Exp $	*/
 /*	$NetBSD: kern_exit.c,v 1.39 1996/04/22 01:38:25 christos Exp $	*/
 
 /*
@@ -502,7 +502,6 @@ dowait6(struct proc *q, idtype_t idtype, id_t id, int *statusp, int options,
 {
 	int nfound;
 	struct process *pr;
-	struct proc *p;
 	int error;
 
 	if (info != NULL)
@@ -516,8 +515,6 @@ loop:
 		    (idtype == P_PGID && id != pr->ps_pgid))
 			continue;
 
-		p = pr->ps_mainproc;
-
 		nfound++;
 		if ((options & WEXITED) && (pr->ps_flags & PS_ZOMBIE)) {
 			*retval = pr->ps_pid;
@@ -571,11 +568,9 @@ loop:
 				memset(rusage, 0, sizeof(*rusage));
 			return (0);
 		}
-		if (p->p_stat == SSTOP &&
+		if (((pr->ps_flags & PS_TRACED) || (options & WUNTRACED)) &&
 		    (pr->ps_flags & PS_WAITED) == 0 &&
-		    (p->p_flag & P_SUSPSINGLE) == 0 &&
-		    ((pr->ps_flags & PS_TRACED) ||
-		    (options & WUNTRACED))) {
+		    (pr->ps_flags & PS_STOPPED)) {
 			if ((options & WNOWAIT) == 0)
 				atomic_setbits_int(&pr->ps_flags, PS_WAITED);
 
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index d7179d0645f..f061b06cffe 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_proc.c,v 1.99 2024/07/08 13:17:12 claudio Exp $	*/
+/*	$OpenBSD: kern_proc.c,v 1.100 2024/10/15 13:49:26 claudio Exp $	*/
 /*	$NetBSD: kern_proc.c,v 1.14 1996/02/09 18:59:41 christos Exp $	*/
 
 /*
@@ -462,7 +462,7 @@ orphanpg(struct pgrp *pg)
 	struct process *pr;
 
 	LIST_FOREACH(pr, &pg->pg_members, ps_pglist) {
-		if (pr->ps_mainproc->p_stat == SSTOP) {
+		if (pr->ps_flags & PS_STOPPED) {
 			LIST_FOREACH(pr, &pg->pg_members, ps_pglist) {
 				prsignal(pr, SIGHUP);
 				prsignal(pr, SIGCONT);
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index db6bf45abaf..c0576093843 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sig.c,v 1.341 2024/10/09 08:58:19 claudio Exp $	*/
+/*	$OpenBSD: kern_sig.c,v 1.342 2024/10/15 13:49:26 claudio Exp $	*/
 /*	$NetBSD: kern_sig.c,v 1.54 1996/04/22 01:38:32 christos Exp $	*/
 
 /*
@@ -1100,6 +1100,8 @@ ptsignal(struct proc *p, int signum, enum signal_type type)
 			 * Otherwise, process goes back to sleep state.
 			 */
 			atomic_setbits_int(&pr->ps_flags, PS_CONTINUED);
+			atomic_clearbits_int(&pr->ps_flags,
+			    PS_WAITED | PS_STOPPED);
 			atomic_clearbits_int(&p->p_flag, P_SUSPSIG);
 			wakeparent = 1;
 			if (action == SIG_DFL)
@@ -1512,6 +1514,7 @@ proc_stop_sweep(void *v)
 	LIST_FOREACH(pr, &allprocess, ps_list) {
 		if ((pr->ps_flags & PS_STOPPING) == 0)
 			continue;
+		atomic_setbits_int(&pr->ps_flags, PS_STOPPED);
 		atomic_clearbits_int(&pr->ps_flags, PS_STOPPING);
 
 		if ((pr->ps_pptr->ps_sigacts->ps_sigflags & SAS_NOCLDSTOP) == 0)
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 0a6fee0f87a..4667ddb9d62 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: proc.h,v 1.374 2024/10/08 12:02:24 claudio Exp $	*/
+/*	$OpenBSD: proc.h,v 1.375 2024/10/15 13:49:26 claudio Exp $	*/
 /*	$NetBSD: proc.h,v 1.44 1996/04/22 01:23:21 christos Exp $	*/
 
 /*-
@@ -304,15 +304,16 @@ struct process {
 #define	PS_NOBTCFI	0x02000000	/* No Branch Target CFI */
 #define	PS_ITIMER	0x04000000	/* Virtual interval timers running */
 #define	PS_CONTINUED	0x20000000	/* Continued proc not yet waited for */
+#define	PS_STOPPED	0x40000000	/* Stopped process */
 
 #define	PS_BITS \
     ("\20" "\01CONTROLT" "\02EXEC" "\03INEXEC" "\04EXITING" "\05SUGID" \
      "\06SUGIDEXEC" "\07PPWAIT" "\010ISPWAIT" "\011PROFIL" "\012TRACED" \
      "\013WAITED" "\014COREDUMP" "\015SINGLEEXIT" "\016SINGLEUNWIND" \
-     "\017NOZOMBIE" "\020STOPPED" "\021SYSTEM" "\022EMBRYO" "\023ZOMBIE" \
+     "\017NOZOMBIE" "\020STOPPING" "\021SYSTEM" "\022EMBRYO" "\023ZOMBIE" \
      "\024NOBROADCASTKILL" "\025PLEDGE" "\026WXNEEDED" "\027EXECPLEDGE" \
-     "\030ORPHAN" "\031CHROOT" "\032NOBTCFI" "\033ITIMER" "\034PIN" \
-     "\035LIBCPIN" "\036CONTINUED")
+     "\030ORPHAN" "\031CHROOT" "\032NOBTCFI" "\033ITIMER" "\036CONTINUED" \
+     "\037STOPPED")
 
 struct kcov_dev;
 struct lock_list_entry;