stop: add nolock option

If the system gets into a bad state, it may become impossible to get
the lxc container locks.  We should still be able to stop containers
in that case.  Add a -L/--nolock option to specify this behavior.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

doc/lxc-stop.sgml.in

@@ -120,6 +120,19 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 	</listitem>
 	</varlistentry>
 
+    <varlistentry>
+	<term>
+	  <option>--nolock </option>
+	</term>
+	<listitem>
+	  <para>
+	This option avoids the use of any of the API lxc locking, and should
+	only be used if <command>lxc-stop</command> is hanging due to a bad
+	system state.
+	  </para>
+	</listitem>
+	</varlistentry>
+
     <varlistentry>
 	<term>
 	  <option>-W,--nowait </option>

src/lxc/arguments.h

@@ -73,6 +73,9 @@ struct lxc_arguments {
 	int hardstop;
 	int shutdown;
 
+	/* for lxc-stop */
+	int nolock;
+
 	/* for lxc-destroy */
 	int force;
 

src/lxc/lxc_stop.c

@@ -33,6 +33,8 @@
 #include "commands.h"
 #include "utils.h"
 
+#define OPT_NO_LOCK OPT_USAGE+1
+
 static int my_parser(struct lxc_arguments* args, int c, char* arg)
 {
 	switch (c) {
@@ -41,6 +43,7 @@ static int my_parser(struct lxc_arguments* args, int c, char* arg)
 	case 't': args->timeout = atoi(arg); break;
 	case 'k': args->hardstop = 1; break;
 	case 's': args->shutdown = 1; break;
+	case OPT_NO_LOCK: args->nolock = 1; break;
 	}
 	return 0;
 }
@@ -51,6 +54,7 @@ static const struct option my_longopts[] = {
 	{"timeout", required_argument, 0, 't'},
 	{"kill", no_argument, 0, 'k'},
 	{"shutdown", no_argument, 0, 's'},
+	{"no-lock", no_argument, 0, OPT_NO_LOCK},
 	LXC_COMMON_OPTIONS
 };
 
@@ -67,6 +71,7 @@ Options :\n\
   -W, --nowait      don't wait for shutdown or reboot to complete\n\
   -t, --timeout=T   wait T seconds before hard-stopping\n\
   -k, --kill        kill container rather than request clean shutdown\n\
+      --nolock      Avoid using API locks\n\
   -s, --shutdown    Only request clean shutdown, don't later force kill\n",
 	.options  = my_longopts,
 	.parser   = my_parser,
@@ -139,6 +144,11 @@ int main(int argc, char *argv[])
 			 my_args.progname, my_args.quiet, my_args.lxcpath[0]))
 		return 1;
 
+	/* shortcut - if locking is bogus, we should be able to kill
+	 * containers at least */
+	if (my_args.nolock)
+		return lxc_cmd_stop(my_args.name, my_args.lxcpath[0]);
+
 	c = lxc_container_new(my_args.name, my_args.lxcpath[0]);
 	if (!c) {
 		fprintf(stderr, "Error opening container\n");