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Reference count ltt_session objects
[lttng-tools.git] / src / bin / lttng-sessiond / main.c
diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 7a0cdb81c83ac0c451341aa41ed29c57d4d3cb77..98f58630712ee720cb71225795c09696a9c9d5f9 100644 (file)
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -177,7 +177,6 @@ static int dispatch_thread_exit;
 /* Sockets and FDs */
 static int client_sock = -1;
 static int apps_sock = -1;
-static int kernel_poll_pipe[2] = { -1, -1 };
 
 /*
  * This pipe is used to inform the thread managing application communication
@@ -211,18 +210,6 @@ static pthread_t timer_thread;
  */
 static struct ust_cmd_queue ust_cmd_queue;
 
-/*
- * Pointer initialized before thread creation.
- *
- * This points to the tracing session list containing the session count and a
- * mutex lock. The lock MUST be taken if you iterate over the list. The lock
- * MUST NOT be taken if you call a public function in session.c.
- *
- * The lock is nested inside the structure: session_list_ptr->lock. Please use
- * session_lock_list and session_unlock_list for lock acquisition.
- */
-static struct ltt_session_list *session_list_ptr;
-
 static const char *module_proc_lttng = "/proc/lttng";
 
 /*
@@ -389,6 +376,7 @@ static void sessiond_cleanup(void)
 {
        int ret;
        struct ltt_session *sess, *stmp;
+       struct ltt_session_list *session_list = session_get_list();
 
        DBG("Cleanup sessiond");
 
@@ -437,15 +425,19 @@ static void sessiond_cleanup(void)
        DBG("Cleaning up all sessions");
 
        /* Destroy session list mutex */
-       if (session_list_ptr != NULL) {
-               pthread_mutex_destroy(&session_list_ptr->lock);
-
+       if (session_list) {
+               session_lock_list();
                /* Cleanup ALL session */
                cds_list_for_each_entry_safe(sess, stmp,
-                               &session_list_ptr->head, list) {
-                       cmd_destroy_session(sess, kernel_poll_pipe[1],
+                               &session_list->head, list) {
+                       if (sess->destroyed) {
+                               continue;
+                       }
+                       cmd_destroy_session(sess,
                                        notification_thread_handle);
                }
+               session_unlock_list();
+               pthread_mutex_destroy(&session_list->lock);
        }
 
        wait_consumer(&kconsumer_data);
@@ -619,16 +611,21 @@ static int setup_lttng_msg_no_cmd_header(struct command_ctx *cmd_ctx,
 static int update_kernel_poll(struct lttng_poll_event *events)
 {
        int ret;
-       struct ltt_session *session;
        struct ltt_kernel_channel *channel;
+       struct ltt_session *session;
+       const struct ltt_session_list *session_list = session_get_list();
 
        DBG("Updating kernel poll set");
 
        session_lock_list();
-       cds_list_for_each_entry(session, &session_list_ptr->head, list) {
+       cds_list_for_each_entry(session, &session_list->head, list) {
+               if (!session_get(session)) {
+                       continue;
+               }
                session_lock(session);
                if (session->kernel_session == NULL) {
                        session_unlock(session);
+                       session_put(session);
                        continue;
                }
 
@@ -638,6 +635,7 @@ static int update_kernel_poll(struct lttng_poll_event *events)
                        ret = lttng_poll_add(events, channel->fd, LPOLLIN | LPOLLRDNORM);
                        if (ret < 0) {
                                session_unlock(session);
+                               session_put(session);
                                goto error;
                        }
                        DBG("Channel fd %d added to kernel set", channel->fd);
@@ -665,14 +663,19 @@ static int update_kernel_stream(int fd)
        struct ltt_session *session;
        struct ltt_kernel_session *ksess;
        struct ltt_kernel_channel *channel;
+       const struct ltt_session_list *session_list = session_get_list();
 
        DBG("Updating kernel streams for channel fd %d", fd);
 
        session_lock_list();
-       cds_list_for_each_entry(session, &session_list_ptr->head, list) {
+       cds_list_for_each_entry(session, &session_list->head, list) {
+               if (!session_get(session)) {
+                       continue;
+               }
                session_lock(session);
                if (session->kernel_session == NULL) {
                        session_unlock(session);
+                       session_put(session);
                        continue;
                }
                ksess = session->kernel_session;
@@ -720,12 +723,14 @@ static int update_kernel_stream(int fd)
                        rcu_read_unlock();
                }
                session_unlock(session);
+               session_put(session);
        }
        session_unlock_list();
        return ret;
 
 error:
        session_unlock(session);
+       session_put(session);
        session_unlock_list();
        return ret;
 }
@@ -737,6 +742,7 @@ error:
 static void update_ust_app(int app_sock)
 {
        struct ltt_session *sess, *stmp;
+       const struct ltt_session_list *session_list = session_get_list();
 
        /* Consumer is in an ERROR state. Stop any application update. */
        if (uatomic_read(&ust_consumerd_state) == CONSUMER_ERROR) {
@@ -745,9 +751,12 @@ static void update_ust_app(int app_sock)
        }
 
        /* For all tracing session(s) */
-       cds_list_for_each_entry_safe(sess, stmp, &session_list_ptr->head, list) {
+       cds_list_for_each_entry_safe(sess, stmp, &session_list->head, list) {
                struct ust_app *app;
 
+               if (!session_get(sess)) {
+                       continue;
+               }
                session_lock(sess);
                if (!sess->ust_session) {
                        goto unlock_session;
@@ -771,6 +780,7 @@ static void update_ust_app(int app_sock)
                rcu_read_unlock();
        unlock_session:
                session_unlock(sess);
+               session_put(sess);
        }
 }
 
@@ -2716,17 +2726,22 @@ static unsigned int lttng_sessions_count(uid_t uid, gid_t gid)
 {
        unsigned int i = 0;
        struct ltt_session *session;
+       const struct ltt_session_list *session_list = session_get_list();
 
        DBG("Counting number of available session for UID %d GID %d",
                        uid, gid);
-       cds_list_for_each_entry(session, &session_list_ptr->head, list) {
-               /*
-                * Only list the sessions the user can control.
-                */
-               if (!session_access_ok(session, uid, gid)) {
+       cds_list_for_each_entry(session, &session_list->head, list) {
+               if (!session_get(session)) {
                        continue;
                }
-               i++;
+               session_lock(session);
+               /* Only count the sessions the user can control. */
+               if (session_access_ok(session, uid, gid) &&
+                               !session->destroyed) {
+                       i++;
+               }
+               session_unlock(session);
+               session_put(session);
        }
        return i;
 }
@@ -3213,7 +3228,8 @@ skip_domain:
        if (need_tracing_session) {
                if (!session_access_ok(cmd_ctx->session,
                                LTTNG_SOCK_GET_UID_CRED(&cmd_ctx->creds),
-                               LTTNG_SOCK_GET_GID_CRED(&cmd_ctx->creds))) {
+                               LTTNG_SOCK_GET_GID_CRED(&cmd_ctx->creds)) ||
+                               cmd_ctx->session->destroyed) {
                        ret = LTTNG_ERR_EPERM;
                        goto error;
                }
@@ -3728,11 +3744,8 @@ error_add_context:
        }
        case LTTNG_DESTROY_SESSION:
        {
-               ret = cmd_destroy_session(cmd_ctx->session, kernel_poll_pipe[1],
+               ret = cmd_destroy_session(cmd_ctx->session,
                                notification_thread_handle);
-
-               /* Set session to NULL so we do not unlock it after free. */
-               cmd_ctx->session = NULL;
                break;
        }
        case LTTNG_LIST_DOMAINS:
@@ -4189,6 +4202,7 @@ error:
 setup_error:
        if (cmd_ctx->session) {
                session_unlock(cmd_ctx->session);
+               session_put(cmd_ctx->session);
        }
        if (need_tracing_session) {
                session_unlock_list();
@@ -5961,12 +5975,6 @@ int main(int argc, char **argv)
        /* Init UST command queue. */
        cds_wfcq_init(&ust_cmd_queue.head, &ust_cmd_queue.tail);
 
-       /*
-        * Get session list pointer. This pointer MUST NOT be free'd. This list
-        * is statically declared in session.c
-        */
-       session_list_ptr = session_get_list();
-
        cmd_init();
 
        /* Check for the application socket timeout env variable. */
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