Add mutex protection for the traceable apps
authorDavid Goulet <david.goulet@polymtl.ca>
Wed, 27 Apr 2011 19:31:56 +0000 (15:31 -0400)
committerDavid Goulet <david.goulet@polymtl.ca>
Wed, 27 Apr 2011 19:33:12 +0000 (15:33 -0400)
The two threads are using this list so now protected
by a pthread_mutex_t using add and del function.

Also introduce add and del function to manage
the session list.

Signed-off-by: David Goulet <david.goulet@polymtl.ca>
ltt-sessiond/ltt-sessiond.c

index a4baafc0761147687a9b03410df5a986dff609a0..45f79a70980a4506b5dfc34f57f0cf17622cce7c 100644 (file)
@@ -61,6 +61,10 @@ static int init_daemon_socket(void);
 static int process_client_msg(int sock, struct lttcomm_session_msg*);
 static int send_unix_sock(int sock, void *buf, size_t len);
 static int setup_data_buffer(char **buf, size_t size, struct lttcomm_lttng_msg *llm);
+static void add_traceable_app(struct ltt_traceable_app *lta);
+static void del_traceable_app(struct ltt_traceable_app *lta);
+static void add_session_list(struct ltt_session *ls);
+static void del_session_list(struct ltt_session *ls);
 
 /* Command function */
 static void get_list_apps(pid_t *pids);
@@ -107,6 +111,9 @@ static struct ltt_traceable_app_list ltt_traceable_app_list = {
        .head = CDS_LIST_HEAD_INIT(ltt_traceable_app_list.head),
 };
 
+/* List mutex */
+pthread_mutex_t ltt_traceable_app_list_mutex;
+
 /*
  *     thread_manage_apps
  *
@@ -154,18 +161,13 @@ static void *thread_manage_apps(void *data)
                        lta = malloc(sizeof(struct ltt_traceable_app));
                        lta->pid = reg_msg.pid;
                        lta->uid = reg_msg.uid;
-                       cds_list_add(&lta->list, &ltt_traceable_app_list.head);
-                       traceable_app_count++;
+                       add_traceable_app(lta);
                } else {
                        /* Unregistering */
                        cds_list_for_each_entry(lta, &ltt_traceable_app_list.head, list) {
                                if (lta->pid == reg_msg.pid && lta->uid == reg_msg.uid) {
-                                       cds_list_del(&lta->list);
+                                       del_traceable_app(lta);
                                        free(lta);
-                                       /* Check to not overflow here */
-                                       if (traceable_app_count != 0) {
-                                               traceable_app_count--;
-                                       }
                                        break;
                                }
                        }
@@ -233,6 +235,62 @@ error:
        return NULL;
 }
 
+/*
+ *  add_traceable_app
+ *
+ *  Add a traceable application structure to the global
+ *  list protected by a mutex.
+ */
+static void add_traceable_app(struct ltt_traceable_app *lta)
+{
+       pthread_mutex_lock(&ltt_traceable_app_list_mutex);
+       cds_list_add(&lta->list, &ltt_traceable_app_list.head);
+       traceable_app_count++;
+       pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
+}
+
+/*
+ *  del_traceable_app
+ *
+ *  Delete a traceable application structure from the
+ *  global list protected by a mutex.
+ */
+static void del_traceable_app(struct ltt_traceable_app *lta)
+{
+       pthread_mutex_lock(&ltt_traceable_app_list_mutex);
+       cds_list_del(&lta->list);
+       /* Sanity check */
+       if (traceable_app_count != 0) {
+               traceable_app_count--;
+       }
+       pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
+}
+
+/*
+ *  add_session_list
+ *
+ *  Add a ltt_session structure to the global list.
+ */
+static void add_session_list(struct ltt_session *ls)
+{
+       cds_list_add(&ls->list, &ltt_session_list.head);
+       session_count++;
+}
+
+/*
+ *  del_session_list
+ *
+ *  Delete a ltt_session structure to the global list.
+ */
+static void del_session_list(struct ltt_session *ls)
+{
+       cds_list_del(&ls->list);
+       /* Sanity check */
+       if (session_count != 0) {
+               session_count--;
+       }
+}
+
 /*
  *  send_unix_sock
  *
@@ -316,12 +374,15 @@ static int find_app_by_pid(pid_t pid)
 {
        struct ltt_traceable_app *iter;
 
+       pthread_mutex_lock(&ltt_traceable_app_list_mutex);
        cds_list_for_each_entry(iter, &ltt_traceable_app_list.head, list) {
                if (iter->pid == pid) {
+                       pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
                        /* Found */
                        return 1;
                }
        }
+       pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
 
        return 0;
 }
@@ -396,9 +457,8 @@ static int destroy_session(uuid_t *uuid)
 
        cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
                if (uuid_compare(iter->uuid, *uuid) == 0) {
-                       cds_list_del(&iter->list);
+                       del_session_list(iter);
                        free(iter);
-                       session_count--;
                        found = 1;
                        break;
                }
@@ -450,9 +510,7 @@ static int create_session(char *name, uuid_t *session_id)
        CDS_INIT_LIST_HEAD(&new_session->lttng_traces);
 
        /* Add new session to the global session list */
-       cds_list_add(&new_session->list, &ltt_session_list.head);
-
-       session_count++;
+       add_session_list(new_session);
 
        return 0;
 
@@ -516,11 +574,15 @@ static void get_list_apps(pid_t *pids)
        int i = 0;
        struct ltt_traceable_app *iter;
 
-       /* TODO: Mutex needed to access this list */
+       /* Protected by a mutex here because the threads manage_client
+        * and manage_apps can access this list.
+        */
+       pthread_mutex_lock(&ltt_traceable_app_list_mutex);
        cds_list_for_each_entry(iter, &ltt_traceable_app_list.head, list) {
                pids[i] = iter->pid;
                i++;
        }
+       pthread_mutex_unlock(&ltt_traceable_app_list_mutex);
 }
 
 /*
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