commit c570f3f4751385153292c85c2f38dc78e9443923
Author: Jason Merrill <jason@redhat.com>
Date:   Sat Sep 14 14:02:20 2019 -0400

            * lock-and-run.sh: Check for process existence rather than timeout.

diff --git a/gcc/lock-and-run.sh b/gcc/lock-and-run.sh
index 3a6a84c253a..b1a4a4c8220 100644
--- a/gcc/lock-and-run.sh
+++ b/gcc/lock-and-run.sh
@@ -5,29 +5,28 @@ lockdir="$1" prog="$2"; shift 2 || exit 1
 
 # Remember when we started trying to acquire the lock.
 count=0
-touch lock-stamp.$$
 
-trap 'rm -r "$lockdir" lock-stamp.$$' 0
+trap 'rm -rf "$lockdir"' 0
 
 until mkdir "$lockdir" 2>/dev/null; do
     # Say something periodically so the user knows what's up.
     if [ `expr $count % 30` = 0 ]; then
-	# Reset if the lock has been renewed.
-	if [ -n "`find \"$lockdir\" -newer lock-stamp.$$`" ]; then
-	    touch lock-stamp.$$
-	    count=1
-	# Steal the lock after 5 minutes.
-	elif [ $count = 300 ]; then
-	    echo removing stale $lockdir >&2
-	    rm -r "$lockdir"
+	# Check for stale lock.
+	pid="`(cd $lockdir; echo *)`"
+	if ps "$pid" >/dev/null; then
+	    echo waiting $count sec to acquire $lockdir from PID $pid>&2
+	    found=$pid
 	else
-	    echo waiting to acquire $lockdir >&2
+	    echo PID $pid is dead, removing stale $lockdir >&2
+	    rm -r "$lockdir"
 	fi
     fi
     sleep 1
     count=`expr $count + 1`
 done
 
+touch $lockdir/$$
+echo acquired $lockdir after $count seconds >&2
 echo $prog "$@"
 $prog "$@"