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 098e199..eaa7266 100644 (file)
--- 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);