Fix RCU-related hangs: incorrect lttng_ht_destroy use

[lttng-tools.git] / src / bin / lttng-sessiond / session.c

diff --git a/src/bin/lttng-sessiond/session.c b/src/bin/lttng-sessiond/session.c
index f9d20cc56dd8ac6bff654f676aa94e2e6c089350..b6b24b76c3f9ae28cec31d3c9e3224351647a2ef 100644 (file)
--- a/src/bin/lttng-sessiond/session.c
+++ b/src/bin/lttng-sessiond/session.c
@@ -45,7 +45,7 @@
 static struct ltt_session_list ltt_session_list = {
        .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
        .lock = PTHREAD_MUTEX_INITIALIZER,
-       .count = 0,
+       .next_uuid = 0,
 };
 
 /*
@@ -56,8 +56,10 @@ static struct ltt_session_list ltt_session_list = {
  */
 static unsigned int add_session_list(struct ltt_session *ls)
 {
+       assert(ls);
+
        cds_list_add(&ls->list, &ltt_session_list.head);
-       return ++ltt_session_list.count;
+       return ltt_session_list.next_uuid++;
 }
 
 /*
@@ -67,11 +69,9 @@ static unsigned int add_session_list(struct ltt_session *ls)
  */
 static void del_session_list(struct ltt_session *ls)
 {
+       assert(ls);
+
        cds_list_del(&ls->list);
-       /* Sanity check */
-       if (ltt_session_list.count > 0) {
-               ltt_session_list.count--;
-       }
 }
 
 /*
@@ -103,6 +103,8 @@ void session_unlock_list(void)
  */
 void session_lock(struct ltt_session *session)
 {
+       assert(session);
+
        pthread_mutex_lock(&session->lock);
 }
 
@@ -111,6 +113,8 @@ void session_lock(struct ltt_session *session)
  */
 void session_unlock(struct ltt_session *session)
 {
+       assert(session);
+
        pthread_mutex_unlock(&session->lock);
 }
 
@@ -123,6 +127,8 @@ struct ltt_session *session_find_by_name(char *name)
 {
        struct ltt_session *iter;
 
+       assert(name);
+
        DBG2("Trying to find session by name %s", name);
 
        cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
@@ -141,27 +147,27 @@ found:
  * Delete session from the session list and free the memory.
  *
  * Return -1 if no session is found.  On success, return 1;
+ * Should *NOT* be called with RCU read-side lock held.
  */
 int session_destroy(struct ltt_session *session)
 {
        /* Safety check */
-       if (session == NULL) {
-               ERR("Session pointer was null on session destroy");
-               return LTTCOMM_OK;
-       }
+       assert(session);
 
        DBG("Destroying session %s", session->name);
        del_session_list(session);
        pthread_mutex_destroy(&session->lock);
+
+       consumer_destroy_output(session->consumer);
        free(session);
 
-       return LTTCOMM_OK;
+       return LTTNG_OK;
 }
 
 /*
  * Create a brand new session and add it to the session list.
  */
-int session_create(char *name, char *path, uid_t uid, gid_t gid)
+int session_create(char *name, uid_t uid, gid_t gid)
 {
        int ret;
        struct ltt_session *new_session;
@@ -170,31 +176,19 @@ int session_create(char *name, char *path, uid_t uid, gid_t gid)
        new_session = zmalloc(sizeof(struct ltt_session));
        if (new_session == NULL) {
                PERROR("zmalloc");
-               ret = LTTCOMM_FATAL;
+               ret = LTTNG_ERR_FATAL;
                goto error_malloc;
        }
 
        /* Define session name */
        if (name != NULL) {
                if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
-                       ret = LTTCOMM_FATAL;
+                       ret = LTTNG_ERR_FATAL;
                        goto error_asprintf;
                }
        } else {
                ERR("No session name given");
-               ret = LTTCOMM_FATAL;
-               goto error;
-       }
-
-       /* Define session system path */
-       if (path != NULL) {
-               if (snprintf(new_session->path, PATH_MAX, "%s", path) < 0) {
-                       ret = LTTCOMM_FATAL;
-                       goto error_asprintf;
-               }
-       } else {
-               ERR("No session path given");
-               ret = LTTCOMM_FATAL;
+               ret = LTTNG_ERR_FATAL;
                goto error;
        }
 
@@ -208,36 +202,40 @@ int session_create(char *name, char *path, uid_t uid, gid_t gid)
        new_session->uid = uid;
        new_session->gid = gid;
 
-       /* Mkdir if we have a valid path length */
-       if (strlen(new_session->path) > 0) {
-               ret = run_as_mkdir_recursive(new_session->path, S_IRWXU | S_IRWXG,
-                               new_session->uid, new_session->gid);
-               if (ret < 0) {
-                       if (ret != -EEXIST) {
-                               ERR("Trace directory creation error");
-                               ret = LTTCOMM_CREATE_DIR_FAIL;
-                               goto error;
-                       }
-               }
-       }
-
        /* Add new session to the session list */
        session_lock_list();
        new_session->id = add_session_list(new_session);
        session_unlock_list();
 
-       DBG("Tracing session %s created in %s with ID %u by UID %d GID %d",
-               name, path, new_session->id,
-               new_session->uid, new_session->gid);
+       /*
+        * Consumer is let to NULL since the create_session_uri command will set it
+        * up and, if valid, assign it to the session.
+        */
+
+       DBG("Tracing session %s created with ID %u by UID %d GID %d", name,
+                       new_session->id, new_session->uid, new_session->gid);
 
-       return LTTCOMM_OK;
+       return LTTNG_OK;
 
 error:
 error_asprintf:
-       if (new_session != NULL) {
-               free(new_session);
-       }
+       free(new_session);
 
 error_malloc:
        return ret;
 }
+
+/*
+ * Check if the UID or GID match the session. Root user has access to all
+ * sessions.
+ */
+int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
+{
+       assert(session);
+
+       if (uid != session->uid && gid != session->gid && uid != 0) {
+               return 0;
+       } else {
+               return 1;
+       }
+}