From: Serge E. Hallyn <serge.hallyn@canonical.com>
Date: Tue, 9 Aug 2011 14:51:01 +0000 (+0200)
Subject: Silence lxc-unshare warning when removing cgroup
X-Git-Tag: lxc-0.7.5~8
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0b9c21ab8ab3e7a1eacdb087950fe9f680053486;p=thirdparty%2Flxc.git

Silence lxc-unshare warning when removing cgroup

If ns cgroup is mounted, then when lxc-unshare runs, the kernel automatically
creates a new cgroup for the task.  So lxc-unshare tries to delete it.  But
if ns cgroup is not mounted, that cgroup does not get created, and now
lxc-unshare spits an error.
Author: Serge Hallyn <serge.hallyn@canonical.com>
Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/819319
Forwarded: no

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
---

diff --git a/src/lxc/cgroup.c b/src/lxc/cgroup.c
index c4769f97b..a2b823e2b 100644
--- a/src/lxc/cgroup.c
+++ b/src/lxc/cgroup.c
@@ -82,6 +82,13 @@ static int get_cgroup_mount(const char *subsystem, char *mnt)
 	return -1;
 }
 
+int lxc_ns_is_mounted(void)
+{
+	static char        buf[MAXPATHLEN];
+
+	return (get_cgroup_mount("ns", buf) == 0);
+}
+
 static int get_cgroup_flags(struct mntent *mntent)
 {
 	int flags = 0;
diff --git a/src/lxc/cgroup.h b/src/lxc/cgroup.h
index f6df8c538..188d94807 100644
--- a/src/lxc/cgroup.h
+++ b/src/lxc/cgroup.h
@@ -30,4 +30,5 @@ int lxc_cgroup_create(const char *name, pid_t pid);
 int lxc_cgroup_destroy(const char *name);
 int lxc_cgroup_path_get(char **path, const char *subsystem, const char *name);
 int lxc_cgroup_nrtasks(const char *name);
+int lxc_ns_is_mounted(void);
 #endif
diff --git a/src/lxc/lxc_unshare.c b/src/lxc/lxc_unshare.c
index eb93c89db..0baccb007 100644
--- a/src/lxc/lxc_unshare.c
+++ b/src/lxc/lxc_unshare.c
@@ -210,12 +210,14 @@ int main(int argc, char *argv[])
 		return -1;
 	}
 
-	if (asprintf(&pid_name, "%d", pid) == -1) {
-		ERROR("pid_name: failed to allocate memory");
-		return -1;
+	if (lxc_ns_is_mounted()) {
+		if (asprintf(&pid_name, "%d", pid) == -1) {
+			ERROR("pid_name: failed to allocate memory");
+			return -1;
+		}
+		lxc_cgroup_destroy(pid_name);
+		free(pid_name);
 	}
-	lxc_cgroup_destroy(pid_name);
-	free(pid_name);
 
 	return  lxc_error_set_and_log(pid, status);
 }