Fix: LPOLLHUP and LPOLLERR when there is still data in pipe/socket

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

diff --git a/src/bin/lttng-sessiond/ust-thread.c b/src/bin/lttng-sessiond/ust-thread.c
index b421eb29560c2d780ddb705224ed52e382003f28..9c944c55288f7470025e47fffbf77ae981fe6199 100644 (file)
--- a/src/bin/lttng-sessiond/ust-thread.c
+++ b/src/bin/lttng-sessiond/ust-thread.c
@@ -57,7 +57,8 @@ void *ust_thread_manage_notify(void *data)
        }
 
        /* Add notify pipe to the pollset. */
-       ret = lttng_poll_add(&events, apps_cmd_notify_pipe[0], LPOLLIN | LPOLLERR);
+       ret = lttng_poll_add(&events, apps_cmd_notify_pipe[0],
+                       LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
        if (ret < 0) {
                goto error;
        }
@@ -109,45 +110,56 @@ restart:
                        if (pollfd == apps_cmd_notify_pipe[0]) {
                                int sock;
 
-                               if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
+                               if (revents & LPOLLIN) {
+                                       /* Get socket from dispatch thread. */
+                                       size_ret = lttng_read(apps_cmd_notify_pipe[0],
+                                                       &sock, sizeof(sock));
+                                       if (size_ret < sizeof(sock)) {
+                                               PERROR("read apps notify pipe");
+                                               goto error;
+                                       }
+                                       health_code_update();
+
+                                       ret = lttng_poll_add(&events, sock,
+                                                       LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
+                                       if (ret < 0) {
+                                               /*
+                                                * It's possible we've reached the max poll fd allowed.
+                                                * Let's close the socket but continue normal execution.
+                                                */
+                                               ret = close(sock);
+                                               if (ret) {
+                                                       PERROR("close notify socket %d", sock);
+                                               }
+                                               lttng_fd_put(LTTNG_FD_APPS, 1);
+                                               continue;
+                                       }
+                                       DBG3("UST thread notify added sock %d to pollset", sock);
+                               } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                        ERR("Apps notify command pipe error");
                                        goto error;
-                               } else if (!(revents & LPOLLIN)) {
-                                       /* No POLLIN and not a catched error, stop the thread. */
-                                       ERR("Notify command pipe failed. revent: %u", revents);
-                                       goto error;
-                               }
-
-                               /* Get socket from dispatch thread. */
-                               size_ret = lttng_read(apps_cmd_notify_pipe[0],
-                                               &sock, sizeof(sock));
-                               if (size_ret < sizeof(sock)) {
-                                       PERROR("read apps notify pipe");
+                               } else {
+                                       ERR("Unexpected poll events %u for sock %d", revents, pollfd);
                                        goto error;
                                }
-                               health_code_update();
-
-                               ret = lttng_poll_add(&events, sock,
-                                               LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
-                               if (ret < 0) {
-                                       /*
-                                        * It's possible we've reached the max poll fd allowed.
-                                        * Let's close the socket but continue normal execution.
-                                        */
-                                       ret = close(sock);
-                                       if (ret) {
-                                               PERROR("close notify socket %d", sock);
-                                       }
-                                       lttng_fd_put(LTTNG_FD_APPS, 1);
-                                       continue;
-                               }
-                               DBG3("UST thread notify added sock %d to pollset", sock);
                        } else {
                                /*
                                 * At this point, we know that a registered application
                                 * triggered the event.
                                 */
-                               if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
+                               if (revents & (LPOLLIN | LPOLLPRI)) {
+                                       ret = ust_app_recv_notify(pollfd);
+                                       if (ret < 0) {
+                                               /* Removing from the poll set */
+                                               ret = lttng_poll_del(&events, pollfd);
+                                               if (ret < 0) {
+                                                       goto error;
+                                               }
+
+                                               /* The socket is closed after a grace period here. */
+                                               ust_app_notify_sock_unregister(pollfd);
+                                       }
+                               } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                        /* Removing from the poll set */
                                        ret = lttng_poll_del(&events, pollfd);
                                        if (ret < 0) {
@@ -156,22 +168,9 @@ restart:
 
                                        /* The socket is closed after a grace period here. */
                                        ust_app_notify_sock_unregister(pollfd);
-                               } else if (revents & (LPOLLIN | LPOLLPRI)) {
-                                       ret = ust_app_recv_notify(pollfd);
-                                       if (ret < 0) {
-                                               /*
-                                                * If the notification failed either the application is
-                                                * dead or an internal error happened. In both cases,
-                                                * we can only continue here. If the application is
-                                                * dead, an unregistration will follow or else the
-                                                * application will notice that we are not responding
-                                                * on that socket and will close it.
-                                                */
-                                               continue;
-                                       }
                                } else {
-                                       ERR("Unknown poll events %u for sock %d", revents, pollfd);
-                                       continue;
+                                       ERR("Unexpected poll events %u for sock %d", revents, pollfd);
+                                       goto error;
                                }
                                health_code_update();
                        }