Fix: compat poll: add missing empty revents checks

Poll returns the entire array, including entries that have no activity.
We need to check them explicitly.

Fixes #747

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-consumerd/health-consumerd.c b/src/bin/lttng-consumerd/health-consumerd.c
index bd47f0c497c042c5ec247f8537a62822f89938e4..fc9a266653f2361efe3a4987bd2640e125761d8c 100644 (file)
--- a/src/bin/lttng-consumerd/health-consumerd.c
+++ b/src/bin/lttng-consumerd/health-consumerd.c
@@ -261,6 +261,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = check_health_quit_pipe(pollfd, revents);
                        if (ret) {

diff --git a/src/bin/lttng-relayd/health-relayd.c b/src/bin/lttng-relayd/health-relayd.c
index af375e26d4b049d5d3d2f0be75c6e302f7a95c10..75149ba4b46526a0494bfea623b3115c676064d4 100644 (file)
--- a/src/bin/lttng-relayd/health-relayd.c
+++ b/src/bin/lttng-relayd/health-relayd.c
@@ -330,6 +330,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = check_health_quit_pipe(pollfd, revents);
                        if (ret) {

diff --git a/src/bin/lttng-relayd/live.c b/src/bin/lttng-relayd/live.c
index fd570e0fc4bd801ebe065e5fd32b2f1c7780323f..756efbedef8434c7126148a7fbdb09e28c57e1e5 100644 (file)
--- a/src/bin/lttng-relayd/live.c
+++ b/src/bin/lttng-relayd/live.c
@@ -488,6 +488,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -1922,6 +1927,11 @@ restart:
 
                        health_code_update();
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = check_thread_quit_pipe(pollfd, revents);
                        if (ret) {

diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index 1ec1eeaa4b14be22fa0a8cde2d708279a50bcf4b..94bb4cb8e6a1ea24924e96e449dbb0c610aee85e 100644 (file)
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -868,6 +868,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -2536,6 +2541,11 @@ restart:
 
                        health_code_update();
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -2638,46 +2648,49 @@ restart:
 
                        health_code_update();
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Skip the command pipe. It's handled in the first loop. */
                        if (pollfd == relay_conn_pipe[0]) {
                                continue;
                        }
 
-                       if (revents) {
-                               rcu_read_lock();
-                               conn = connection_find_by_sock(relay_connections_ht, pollfd);
-                               if (!conn) {
-                                       /* Skip it. Might be removed before. */
+                       rcu_read_lock();
+                       conn = connection_find_by_sock(relay_connections_ht, pollfd);
+                       if (!conn) {
+                               /* Skip it. Might be removed before. */
+                               rcu_read_unlock();
+                               continue;
+                       }
+
+                       if (revents & LPOLLIN) {
+                               if (conn->type != RELAY_DATA) {
                                        rcu_read_unlock();
                                        continue;
                                }
 
-                               if (revents & LPOLLIN) {
-                                       if (conn->type != RELAY_DATA) {
-                                               rcu_read_unlock();
-                                               continue;
-                                       }
-
-                                       ret = relay_process_data(conn);
-                                       /* Connection closed */
-                                       if (ret < 0) {
-                                               cleanup_connection_pollfd(&events, pollfd);
-                                               destroy_connection(relay_connections_ht, conn);
-                                               DBG("Data connection closed with %d", pollfd);
-                                               /*
-                                                * Every goto restart call sets the last seen fd where
-                                                * here we don't really care since we gracefully
-                                                * continue the loop after the connection is deleted.
-                                                */
-                                       } else {
-                                               /* Keep last seen port. */
-                                               last_seen_data_fd = pollfd;
-                                               rcu_read_unlock();
-                                               goto restart;
-                                       }
+                               ret = relay_process_data(conn);
+                               /* Connection closed */
+                               if (ret < 0) {
+                                       cleanup_connection_pollfd(&events, pollfd);
+                                       destroy_connection(relay_connections_ht, conn);
+                                       DBG("Data connection closed with %d", pollfd);
+                                       /*
+                                        * Every goto restart call sets the last seen fd where
+                                        * here we don't really care since we gracefully
+                                        * continue the loop after the connection is deleted.
+                                        */
+                               } else {
+                                       /* Keep last seen port. */
+                                       last_seen_data_fd = pollfd;
+                                       rcu_read_unlock();
+                                       goto restart;
                                }
-                               rcu_read_unlock();
                        }
+                       rcu_read_unlock();
                }
                last_seen_data_fd = -1;
        }

diff --git a/src/bin/lttng-sessiond/agent-thread.c b/src/bin/lttng-sessiond/agent-thread.c
index d7d9c6c349412ba659c3d3720e950b18ac3b8389..a9cc6e735ae0ec4097d7a3a72df4793e06d7bc41 100644 (file)
--- a/src/bin/lttng-sessiond/agent-thread.c
+++ b/src/bin/lttng-sessiond/agent-thread.c
@@ -330,6 +330,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {

diff --git a/src/bin/lttng-sessiond/ht-cleanup.c b/src/bin/lttng-sessiond/ht-cleanup.c
index ace41e5cd5654f6a791e50c82fe90bcc8c406722..373c913dccae1bbb484fefc8e518b9c3821ef255 100644 (file)
--- a/src/bin/lttng-sessiond/ht-cleanup.c
+++ b/src/bin/lttng-sessiond/ht-cleanup.c
@@ -96,6 +96,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        if (pollfd != ht_cleanup_pipe[0]) {
                                continue;
                        }
@@ -140,6 +145,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        if (pollfd == ht_cleanup_pipe[0]) {
                                continue;
                        }

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 0dbec232fe90c3dcca0e9fea4166fee09099e592..80eebf163a10af74b1edfdc1069ccd830050bdbb 100644 (file)
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -1090,6 +1090,11 @@ static void *thread_manage_kernel(void *data)
 
                        health_code_update();
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -1235,6 +1240,11 @@ restart:
 
                health_code_update();
 
+               if (!revents) {
+                       /* No activity for this FD (poll implementation). */
+                       continue;
+               }
+
                /* Thread quit pipe has been closed. Killing thread. */
                ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                if (ret) {
@@ -1362,6 +1372,11 @@ restart_poll:
 
                        health_code_update();
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /*
                         * Thread quit pipe has been triggered, flag that we should stop
                         * but continue the current loop to handle potential data from
@@ -1538,6 +1553,11 @@ static void *thread_manage_apps(void *data)
 
                        health_code_update();
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -1716,6 +1736,11 @@ static void sanitize_wait_queue(struct ust_reg_wait_queue *wait_queue)
                uint32_t revents = LTTNG_POLL_GETEV(&events, i);
                int pollfd = LTTNG_POLL_GETFD(&events, i);
 
+               if (!revents) {
+                       /* No activity for this FD (poll implementation). */
+                       continue;
+               }
+
                cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
                                &wait_queue->head, head) {
                        if (pollfd == wait_node->app->sock &&
@@ -2055,6 +2080,11 @@ static void *thread_registration_apps(void *data)
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -3918,6 +3948,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -4090,6 +4125,11 @@ static void *thread_manage_clients(void *data)
 
                        health_code_update();
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {

diff --git a/src/bin/lttng-sessiond/ust-thread.c b/src/bin/lttng-sessiond/ust-thread.c
index d92c1f9082882b428886edf8df89d31e10ee713b..6f4295db77833416893a16ce0b16288f04b87d3d 100644 (file)
--- a/src/bin/lttng-sessiond/ust-thread.c
+++ b/src/bin/lttng-sessiond/ust-thread.c
@@ -92,6 +92,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {

diff --git a/src/common/consumer.c b/src/common/consumer.c
index d192d7a5194cb6b439a33ebd68e38a2ce5560629..0035aae82d51e1afaa538fddfeb6e7463bfa53db 100644 (file)
--- a/src/common/consumer.c
+++ b/src/common/consumer.c
@@ -2212,6 +2212,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
+                       if (!revents) {
+                               /* No activity for this FD (poll implementation). */
+                               continue;
+                       }
+
                        if (pollfd == lttng_pipe_get_readfd(ctx->consumer_metadata_pipe)) {
                                if (revents & (LPOLLERR | LPOLLHUP )) {
                                        DBG("Metadata thread pipe hung up");
@@ -2782,10 +2787,11 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
-                       /* Just don't waste time if no returned events for the fd */
                        if (!revents) {
+                               /* No activity for this FD (poll implementation). */
                                continue;
                        }
+
                        if (pollfd == ctx->consumer_channel_pipe[0]) {
                                if (revents & (LPOLLERR | LPOLLHUP)) {
                                        DBG("Channel thread pipe hung up");