sessiond: dispatch.cpp: iterate on list using list_iteration_adapter

Change-Id: Ie8a45753922b0a5dd476be06ce15a1f7d6883c08
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/dispatch.cpp b/src/bin/lttng-sessiond/dispatch.cpp
index 32d50a25eee38e5171879756438e923443f7b536..058582ec316a8345e99d1377386e38434ce5b626 100644 (file)
--- a/src/bin/lttng-sessiond/dispatch.cpp
+++ b/src/bin/lttng-sessiond/dispatch.cpp
@@ -38,7 +38,6 @@ struct thread_notifiers {
  */
 static void update_ust_app(int app_sock)
 {
-       struct ltt_session *sess, *stmp;
        const struct ltt_session_list *session_list = session_get_list();
        struct ust_app *app;
 
@@ -65,7 +64,8 @@ static void update_ust_app(int app_sock)
        ust_app_global_update_event_notifier_rules(app);
 
        /* For all tracing session(s) */
-       cds_list_for_each_entry_safe (sess, stmp, &session_list->head, list) {
+       for (auto *sess : lttng::urcu::list_iteration_adapter<ltt_session, &ltt_session::list>(
+                    session_list->head)) {
                if (!session_get(sess)) {
                        continue;
                }
@@ -91,7 +91,6 @@ static void sanitize_wait_queue(struct ust_reg_wait_queue *wait_queue)
        int ret, nb_fd = 0, i;
        unsigned int fd_added = 0;
        struct lttng_poll_event events;
-       struct ust_reg_wait_node *wait_node = nullptr, *tmp_wait_node;
 
        LTTNG_ASSERT(wait_queue);
 
@@ -107,7 +106,9 @@ static void sanitize_wait_queue(struct ust_reg_wait_queue *wait_queue)
                goto error_create;
        }
 
-       cds_list_for_each_entry_safe (wait_node, tmp_wait_node, &wait_queue->head, head) {
+       for (auto *wait_node :
+            lttng::urcu::list_iteration_adapter<ust_reg_wait_node, &ust_reg_wait_node::head>(
+                    wait_queue->head)) {
                LTTNG_ASSERT(wait_node->app);
                ret = lttng_poll_add(&events, wait_node->app->sock, LPOLLIN);
                if (ret < 0) {
@@ -136,18 +137,16 @@ static void sanitize_wait_queue(struct ust_reg_wait_queue *wait_queue)
                const uint32_t revents = LTTNG_POLL_GETEV(&events, i);
                const int pollfd = LTTNG_POLL_GETFD(&events, i);
 
-               cds_list_for_each_entry_safe (wait_node, tmp_wait_node, &wait_queue->head, head) {
+               for (auto *wait_node :
+                    lttng::urcu::list_iteration_adapter<ust_reg_wait_node,
+                                                        &ust_reg_wait_node::head>(
+                            wait_queue->head)) {
                        if (pollfd == wait_node->app->sock && (revents & (LPOLLHUP | LPOLLERR))) {
                                cds_list_del(&wait_node->head);
                                wait_queue->count--;
                                ust_app_put(wait_node->app);
                                free(wait_node);
 
-                               /*
-                                * Silence warning of use-after-free in
-                                * cds_list_for_each_entry_safe which uses
-                                * __typeof__(*wait_node).
-                                */
                                wait_node = nullptr;
                                break;
                        } else {
@@ -224,7 +223,7 @@ static void *thread_dispatch_ust_registration(void *data)
        int ret, err = -1;
        struct cds_wfcq_node *node;
        struct ust_command *ust_cmd = nullptr;
-       struct ust_reg_wait_node *wait_node = nullptr, *tmp_wait_node;
+       struct ust_reg_wait_node *wait_node = nullptr;
        struct ust_reg_wait_queue wait_queue = {
                .count = 0,
                .head = {},
@@ -338,16 +337,19 @@ static void *thread_dispatch_ust_registration(void *data)
                                 * Look for the application in the local wait queue and set the
                                 * notify socket if found.
                                 */
-                               cds_list_for_each_entry_safe (
-                                       wait_node, tmp_wait_node, &wait_queue.head, head) {
+                               for (auto *wait_node_in_queue :
+                                    lttng::urcu::list_iteration_adapter<ust_reg_wait_node,
+                                                                        &ust_reg_wait_node::head>(
+                                            wait_queue.head)) {
                                        health_code_update();
-                                       if (wait_node->app->pid == ust_cmd->reg_msg.pid) {
-                                               wait_node->app->notify_sock = ust_cmd->sock;
-                                               cds_list_del(&wait_node->head);
+                                       if (wait_node_in_queue->app->pid == ust_cmd->reg_msg.pid) {
+                                               wait_node_in_queue->app->notify_sock =
+                                                       ust_cmd->sock;
+                                               cds_list_del(&wait_node_in_queue->head);
                                                wait_queue.count--;
-                                               app = wait_node->app;
-                                               free(wait_node);
-                                               wait_node = nullptr;
+                                               app = wait_node_in_queue->app;
+                                               free(wait_node_in_queue);
+
                                                DBG3("UST app notify socket %d is set",
                                                     ust_cmd->sock);
                                                break;
@@ -447,10 +449,12 @@ static void *thread_dispatch_ust_registration(void *data)
 
 error:
        /* Clean up wait queue. */
-       cds_list_for_each_entry_safe (wait_node, tmp_wait_node, &wait_queue.head, head) {
-               cds_list_del(&wait_node->head);
+       for (auto *wait_node_in_queue :
+            lttng::urcu::list_iteration_adapter<ust_reg_wait_node, &ust_reg_wait_node::head>(
+                    wait_queue.head)) {
+               cds_list_del(&wait_node_in_queue->head);
                wait_queue.count--;
-               free(wait_node);
+               free(wait_node_in_queue);
        }
 
        /* Empty command queue. */

diff --git a/src/common/urcu.hpp b/src/common/urcu.hpp
index 6466fac4309896c531a7e85c7226f09af28b62b0..c5b4c13c048cc9082255e9484716d79fc219c34b 100644 (file)
--- a/src/common/urcu.hpp
+++ b/src/common/urcu.hpp
@@ -345,7 +345,7 @@ public:
                cds_list_head _node_contents;
        };
 
-       explicit list_iteration_adapter(cds_list_head& list) : _list(list)
+       explicit list_iteration_adapter(const cds_list_head& list) : _list(list)
        {
        }
 
@@ -363,7 +363,7 @@ public:
 
 protected:
        /* Reference to the list being iterated over. */
-       cds_list_head& _list;
+       const cds_list_head& _list;
 };
 
 template <typename ContainedType, cds_list_head ContainedType::*Member>
@@ -396,7 +396,7 @@ public:
                }
        };
 
-       explicit rcu_list_iteration_adapter(cds_list_head& list) :
+       explicit rcu_list_iteration_adapter(const cds_list_head& list) :
                list_iteration_adapter<ContainedType, Member>(list)
        {
        }