Rev 300: reading on the write side of a pipe isn't allowed - this caused us to run without locking in the lockwait code in http://samba.org/~tridge/ctdb

[tridge at samba.org]

------------------------------------------------------------
revno: 300
revision-id: tridge at samba.org-20070514234403-ghdhn9vpf6fyqnhq
parent: tridge at samba.org-20070514234252-lkr0iynk4eys7ff1
committer: Andrew Tridgell <tridge at samba.org>
branch nick: tridge
timestamp: Tue 2007-05-15 09:44:03 +1000
message:
  reading on the write side of a pipe isn't allowed - this caused us to run without locking in the lockwait code
modified:
  common/ctdb_lockwait.c         ctdb_lockwait.c-20070416214118-n1aeonljj3vpdd9q-1
=== modified file 'common/ctdb_lockwait.c'
--- a/common/ctdb_lockwait.c	2007-05-14 04:01:33 +0000
+++ b/common/ctdb_lockwait.c	2007-05-14 23:44:03 +0000
@@ -57,10 +57,16 @@
 	ctdb_latency(&h->ctdb->status.max_lockwait_latency, h->start_time);
 	h->ctdb->status.pending_lockwait_calls--;
 
-	/* the fde needs to go away when the context is gone - when
-	   the fde goes away this implicitly closes the pipe, which
+	/* the handle needs to go away when the context is gone - when
+	   the handle goes away this implicitly closes the pipe, which
 	   kills the child holding the lock */
-	talloc_steal(tmp_ctx, fde);
+	talloc_steal(tmp_ctx, h);
+
+	if (h->ctdb->flags & CTDB_FLAG_TORTURE) {
+		if (tdb_chainlock_nonblock(tdb, key) == 0) {
+			ctdb_fatal(h->ctdb, "got chain lock while lockwait child active");
+		}
+	}
 
 	tdb_chainlock_mark(tdb, key);
 	callback(p);
@@ -96,6 +102,7 @@
 {
 	struct lockwait_handle *result;
 	int ret;
+	pid_t parent = getpid();
 
 	ctdb_db->ctdb->status.lockwait_calls++;
 	ctdb_db->ctdb->status.pending_lockwait_calls++;
@@ -134,9 +141,10 @@
 		close(result->fd[0]);
 		tdb_chainlock(ctdb_db->ltdb->tdb, key);
 		write(result->fd[1], &c, 1);
-		/* this read will exit when the parent closes its end
-		   of the pipe, or the parent dies */
-		read(result->fd[1], &c, 1);
+		/* make sure we die when our parent dies */
+		while (kill(parent, 0) == 0 || errno != ESRCH) {
+			sleep(5);
+		}
 		_exit(0);
 	}