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

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

diff --git a/src/bin/lttng-sessiond/agent-thread.c b/src/bin/lttng-sessiond/agent-thread.c
index d1bb122c171d9158b343f504497e5fba2fe64382..2b6f776dd1d2af6010dd9c3c4f550e6873d0280d 100644 (file)
--- a/src/bin/lttng-sessiond/agent-thread.c
+++ b/src/bin/lttng-sessiond/agent-thread.c
@@ -296,35 +296,22 @@ restart:
                                goto exit;
                        }
 
-                       /*
-                        * Check first if this is a POLLERR since POLLIN is also included
-                        * in an error value thus checking first.
-                        */
-                       if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
-                               /* Removing from the poll set */
-                               ret = lttng_poll_del(&events, pollfd);
-                               if (ret < 0) {
-                                       goto error;
-                               }
-
-                               agent_destroy_app_by_sock(pollfd);
-                       } else if (revents & (LPOLLIN)) {
+                       if (revents & LPOLLIN) {
                                int new_fd;
                                struct agent_app *app = NULL;
 
-                               /* Pollin event of agent app socket should NEVER happen. */
                                assert(pollfd == reg_sock->fd);
-
                                new_fd = handle_registration(reg_sock, &app);
                                if (new_fd < 0) {
-                                       WARN("[agent-thread] agent registration failed. Ignoring.");
-                                       /* Somehow the communication failed. Just continue. */
                                        continue;
                                }
                                /* Should not have a NULL app on success. */
                                assert(app);
 
-                               /* Only add poll error event to only detect shutdown. */
+                               /*
+                                * Since this is a command socket (write then read),
+                                * only add poll error event to only detect shutdown.
+                                */
                                ret = lttng_poll_add(&events, new_fd,
                                                LPOLLERR | LPOLLHUP | LPOLLRDHUP);
                                if (ret < 0) {
@@ -336,10 +323,26 @@ restart:
                                update_agent_app(app);
 
                                /* On failure, the poll will detect it and clean it up. */
-                               (void) agent_send_registration_done(app);
+                               ret = agent_send_registration_done(app);
+                               if (ret < 0) {
+                                       /* Removing from the poll set */
+                                       ret = lttng_poll_del(&events, new_fd);
+                                       if (ret < 0) {
+                                               goto error;
+                                       }
+                                       agent_destroy_app_by_sock(new_fd);
+                                       continue;
+                               }
+                       } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
+                               /* Removing from the poll set */
+                               ret = lttng_poll_del(&events, pollfd);
+                               if (ret < 0) {
+                                       goto error;
+                               }
+                               agent_destroy_app_by_sock(pollfd);
                        } else {
-                               ERR("Unknown poll events %u for sock %d", revents, pollfd);
-                               continue;
+                               ERR("Unexpected poll events %u for sock %d", revents, pollfd);
+                               goto error;
                        }
                }
        }