MFC r275616:

Thread waiting for the vfork(2)-ed child to exec or exit, must allow
for the suspension.

MFC r275683 (by andreast):
Fix build for powerpc(32|64) kernels.

MFC r275686 (by andreast):
Fix kernel build for booke.

r275639 (by andrew) is not merged, since arm/arm/syscall.c is not
present on the stable/10 branch, and arm/arm/trap.c already includes
sys/kernel.h.

2 files changed, 27 insertions, 4 deletions

diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c
index 122a13d..8a49311 100644
--- a/sys/kern/kern_thread.c
+++ b/sys/kern/kern_thread.c
@@ -724,6 +724,19 @@ stopme:
 	return (0);
 }
 
+bool
+thread_suspend_check_needed(void)
+{
+	struct proc *p;
+	struct thread *td;
+
+	td = curthread;
+	p = td->td_proc;
+	PROC_LOCK_ASSERT(p, MA_OWNED);
+	return (P_SHOULDSTOP(p) || ((p->p_flag & P_TRACED) != 0 &&
+	    (td->td_dbgflags & TDB_SUSPEND) != 0));
+}
+
 /*
  * Called in from locations that can safely check to see
  * whether we have to suspend or at least throttle for a
@@ -768,8 +781,7 @@ thread_suspend_check(int return_instead)
 	p = td->td_proc;
 	mtx_assert(&Giant, MA_NOTOWNED);
 	PROC_LOCK_ASSERT(p, MA_OWNED);
-	while (P_SHOULDSTOP(p) ||
-	      ((p->p_flag & P_TRACED) && (td->td_dbgflags & TDB_SUSPEND))) {
+	while (thread_suspend_check_needed()) {
 		if (P_SHOULDSTOP(p) == P_STOPPED_SINGLE) {
 			KASSERT(p->p_singlethread != NULL,
 			    ("singlethread not set"));
diff --git a/sys/kern/subr_syscall.c b/sys/kern/subr_syscall.c
index 3d6dc5a..32872bc 100644
--- a/sys/kern/subr_syscall.c
+++ b/sys/kern/subr_syscall.c
@@ -227,9 +227,20 @@ syscallret(struct thread *td, int error, struct syscall_args *sa __unused)
 		 */
 		td->td_pflags &= ~TDP_RFPPWAIT;
 		p2 = td->td_rfppwait_p;
+again:
 		PROC_LOCK(p2);
-		while (p2->p_flag & P_PPWAIT)
-			cv_wait(&p2->p_pwait, &p2->p_mtx);
+		while (p2->p_flag & P_PPWAIT) {
+			PROC_LOCK(p);
+			if (thread_suspend_check_needed()) {
+				PROC_UNLOCK(p2);
+				thread_suspend_check(0);
+				PROC_UNLOCK(p);
+				goto again;
+			} else {
+				PROC_UNLOCK(p);
+			}
+			cv_timedwait(&p2->p_pwait, &p2->p_mtx, hz);
+		}
 		PROC_UNLOCK(p2);
 	}
 }