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 a6948b2f25ba8f64d3afb013790d4a97428c8213..5b82fadd2b70f94882c7357ba167a17285b72ae0 100644 (file)
--- a/src/lxc/commands.c
+++ b/src/lxc/commands.c
@@ -829,9 +829,8 @@ 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,
@@ -840,17 +839,10 @@ 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;
@@ -860,11 +852,19 @@ 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;
 }
 
@@ -883,10 +883,7 @@ 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..986d9904b35d024e8100431d0659f3115f45ef07 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;
 
@@ -210,12 +211,17 @@ int lxc_add_state_client(int state_client_fd, struct lxc_handler *handler,
                return -ENOMEM;
        }
 
-       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 4e877356205527de76ce75f99ae96a619a0b6298..1892df6521a27ba584c781a60b4d17b4da61a4c6 100644 (file)
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -351,10 +351,10 @@ 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));
 
-       process_lock();
        if (lxc_list_empty(&handler->state_clients)) {
                TRACE("No state clients registered");
                process_unlock();