commands: tweak locking

Take the lock on the list after we've done all necessary work and check state.
If we are in requested state, do cleanup and return without adding the state
client to the state client list.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/commands.c b/src/lxc/commands.c
index 0c7d0d7393225149dde71c3bba3e6b654da7e421..a78921e73d369113d870a98c02cdeb1b10c075dc 100644 (file)
--- a/src/lxc/commands.c
+++ b/src/lxc/commands.c
@@ -830,9 +830,8 @@ int lxc_cmd_add_state_client(const char *name, const char *lxcpath,
                             lxc_state_t states[MAX_STATE],
                             int *state_client_fd)
 {
-       int stopped;
+       int state, stopped;
        ssize_t ret;
-       int state = -1;
        struct lxc_cmd_rr cmd = {
            .req = {
                .cmd     = LXC_CMD_ADD_STATE_CLIENT,
@@ -841,17 +840,10 @@ int lxc_cmd_add_state_client(const char *name, const char *lxcpath,
            },
        };
 
-       /* Check if already in requested state. */
-       state = lxc_getstate(name, lxcpath);
-       if (state < 0) {
-               TRACE("%s - Failed to retrieve state of container", strerror(errno));
-               return -1;
-       } else if (states[state]) {
-               TRACE("Container is %s state", lxc_state2str(state));
-               return state;
-       }
-
        ret = lxc_cmd(name, &cmd, &stopped, lxcpath, NULL);
+       if (states[STOPPED] != 0 && stopped != 0)
+               return STOPPED;
+
        if (ret < 0) {
                ERROR("%s - Failed to execute command", strerror(errno));
                return -1;
@@ -861,11 +853,19 @@ int lxc_cmd_add_state_client(const char *name, const char *lxcpath,
         * function.
         */
        if (cmd.rsp.ret < 0) {
-               ERROR("Failed to receive socket fd");
+               ERROR("%s - Failed to receive socket fd", strerror(-cmd.rsp.ret));
                return -1;
        }
 
+       state = PTR_TO_INT(cmd.rsp.data);
+       if (state < MAX_STATE) {
+               TRACE("Container is already in requested state %s",
+                     lxc_state2str(state));
+               return state;
+       }
+
        *state_client_fd = cmd.rsp.ret;
+       TRACE("Added state client %d to state client list", cmd.rsp.ret);
        return MAX_STATE;
 }
 
@@ -884,10 +884,7 @@ static int lxc_cmd_add_state_client_callback(int fd, struct lxc_cmd_req *req,
                return -1;
 
        rsp.ret = lxc_add_state_client(fd, handler, (lxc_state_t *)req->data);
-       if (rsp.ret < 0)
-               ERROR("Failed to add state client %d to state client list", fd);
-       else
-               TRACE("Added state client %d to state client list", fd);
+       rsp.data = INT_TO_PTR(rsp.ret);
 
        return lxc_cmd_rsp_send(fd, &rsp);
 }

diff --git a/src/lxc/commands_utils.c b/src/lxc/commands_utils.c
index e03022f2821ab467ac966b58b0348cc1c7b253e7..e1de26e07c35ef920344c97029c43fa95e6940a2 100644 (file)
--- a/src/lxc/commands_utils.c
+++ b/src/lxc/commands_utils.c
@@ -193,6 +193,7 @@ int lxc_cmd_connect(const char *name, const char *lxcpath,
 int lxc_add_state_client(int state_client_fd, struct lxc_handler *handler,
                         lxc_state_t states[MAX_STATE])
 {
+       int state;
        struct state_client *newclient;
        struct lxc_list *tmplist;
 
@@ -211,11 +212,17 @@ int lxc_add_state_client(int state_client_fd, struct lxc_handler *handler,
        }
 
        process_lock();
-       lxc_list_add_elem(tmplist, newclient);
-       lxc_list_add_tail(&handler->state_clients, tmplist);
-       process_unlock();
+       state = handler->state;
+       if (states[state] != 1) {
+               lxc_list_add_elem(tmplist, newclient);
+               lxc_list_add_tail(&handler->state_clients, tmplist);
+               process_unlock();
+       } else {
+               process_unlock();
+               free(newclient);
+               return state;
+       }
 
        TRACE("added state client %d to state client list", state_client_fd);
-
-       return 0;
+       return MAX_STATE;
 }

diff --git a/src/lxc/start.c b/src/lxc/start.c
index 5dfef2ef568e4960de2956dfd1cf14f5b48d9364..0adce3bbd7f5a1db17b7459198769669b043753d 100644 (file)
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -364,6 +364,7 @@ static int lxc_serve_state_clients(const char *name,
        struct state_client *client;
        struct lxc_msg msg = {.type = lxc_msg_state, .value = state};
 
+       process_lock();
        handler->state = state;
        TRACE("Set container state to %s", lxc_state2str(state));