1 files changed, 20 insertions, 3 deletions

diff --git a/fw/src/fw.c b/fw/src/fw.c
index bb97960..800e004 100644
--- a/fw/src/fw.c
+++ b/fw/src/fw.c
@@ -1463,9 +1463,26 @@ threadmain(int argc, char **argv)
 		 * that has no card behind it and no network at all, which
 		 * is a bad way to discover a typo in -m.
 		 */
-		if(access(mtpt, AEXIST) < 0)
-			sysfatal("%s: %r; not touching %s until it exists",
-				mtpt, etherdev);
+		if(access(mtpt, AEXIST) < 0){
+			/*
+			 * A fw that died left its control filesystem mounted
+			 * here and what remains is a corpse: the name is
+			 * there and every operation on it fails, including
+			 * the check above.  So the restart after a crash was
+			 * refused by the very test meant to keep fw from
+			 * taking a card it could not then serve.  Clear it,
+			 * the same way reclaim() clears the pkt interface the
+			 * same dead fw left behind; both are its wreckage,
+			 * and a firewall that cannot restart into its own
+			 * wreckage stays down for good.
+			 */
+			unmount(nil, mtpt);
+			if(access(mtpt, AEXIST) < 0)
+				sysfatal("%s: %r; not touching %s until it exists",
+					mtpt, etherdev);
+			fprint(2, "fw: cleared %s, left mounted by an earlier fw\n",
+				mtpt);
+		}
 
 		fprint(2, "fw: filtering packets on %s\n", etherdev);
 		syslog(0, "fw", "started, filtering %s for %s", etherdev, etheraddr);