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]

------------------------------------------------------------
revno: 300
revision-id: [EMAIL PROTECTED]
parent: [EMAIL PROTECTED]
committer: Andrew Tridgell <[EMAIL PROTECTED]>
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);
        }