[Lxc-users] [PATCH 1/1] do check for utmp checking at the right time

[Serge Hallyn]

We were doing the check for whether we need to watch utmp from a
thread cloned from that which will actually do the utmp watching.
As a result, the utmp file was always being watched, even if it
didn't need to be.

Move the check to the parent thread.

Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/948623

Signed-off-by: Serge Hallyn <serge.hallyn at canonical.com>
---
 src/lxc/start.c |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/lxc/start.c b/src/lxc/start.c
index eb26be2..ec48a48 100644
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -506,16 +506,12 @@ static int do_start(void *data)
 	if (lxc_sync_barrier_parent(handler, LXC_SYNC_CONFIGURE))
 		return -1;
 
-	if (must_drop_cap_sys_boot()) {
+	if (handler->conf->need_utmp_watch) {
 		if (prctl(PR_CAPBSET_DROP, CAP_SYS_BOOT, 0, 0, 0)) {
 			SYSERROR("failed to remove CAP_SYS_BOOT capability");
 			return -1;
 		}
-		handler->conf->need_utmp_watch = 1;
 		DEBUG("Dropped cap_sys_boot\n");
-	} else {
-		DEBUG("Not dropping cap_sys_boot or watching utmp\n");
-		handler->conf->need_utmp_watch = 0;
 	}
 
 	/* Setup the container, ip, names, utsname, ... */
@@ -638,6 +634,14 @@ int __lxc_start(const char *name, struct lxc_conf *conf,
 	handler->ops = ops;
 	handler->data = data;
 
+	if (must_drop_cap_sys_boot()) {
+		handler->conf->need_utmp_watch = 1;
+		DEBUG("Dropping cap_sys_boot and watching utmp\n");
+	} else {
+		DEBUG("Not dropping cap_sys_boot or watching utmp\n");
+		handler->conf->need_utmp_watch = 0;
+	}
+
 	err = lxc_spawn(handler);
 	if (err) {
 		ERROR("failed to spawn '%s'", name);
-- 
1.7.9.1