From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Thu, 16 Aug 2012 00:49:47 +0000 (-0700)
Subject: Kernel - Fix numerous procfs/ptrace issues (2)
X-Git-Tag: v3.2.0~387
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/3c319633569e3d5212b1b525fd5216a542996a9e

Kernel - Fix numerous procfs/ptrace issues (2)

* The last fix wasn't quite right.  Fix it for real.
---

diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index bda5911fb8..728b9c5e5c 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -177,15 +177,20 @@ pstall(struct proc *p, const char *wmesg, int count)
 		tsleep_interlock(&p->p_lock, 0);
 
 		/*
-		 * If someone is trying to single-step the process they can
-		 * prevent us from going into zombie-land.
+		 * If someone is trying to single-step the process during
+		 * an exec or an exit they can deadlock us because procfs
+		 * sleeps with the process held.
 		 */
-		if (p->p_step) {
-			spin_lock(&p->p_spin);
-			p->p_stops = 0;
-			p->p_step = 0;
-			spin_unlock(&p->p_spin);
-			wakeup(&p->p_step);
+		if (p->p_stops) {
+			if (p->p_flags & P_INEXEC) {
+				wakeup(&p->p_stype);
+			} else if (p->p_flags & P_POSTEXIT) {
+				spin_lock(&p->p_spin);
+				p->p_stops = 0;
+				p->p_step = 0;
+				spin_unlock(&p->p_spin);
+				wakeup(&p->p_stype);
+			}
 		}
 
 		if (atomic_cmpset_int(&p->p_lock, o, n)) {