From 44c180cac90d0c2a0486d6bc1aeaf0f1538c1075 Mon Sep 17 00:00:00 2001 From: Jonathan Rajotte Date: Thu, 9 Jul 2020 14:57:57 -0400 Subject: [PATCH] Fix: partial recv lead to client disconnect MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit On EWOULDBLOCK and EAGAIN, the ret value from `lttcomm_send_unix_sock_non_block` and `lttcomm_recv_unix_sock_non_block` would be equal to -1. Solution ===== For such cases, set ret equal to zero since it is effectively what was received/sent. Caller should treat ret >= 0 as `success` anyway. Signed-off-by: Jonathan Rajotte Signed-off-by: Jérémie Galarneau Change-Id: I47677f26850bf544f672d270972de7cc2c6a2817 --- .../notification-thread-events.c | 3 +- src/common/unix.c | 43 +++++++++++++++---- 2 files changed, 36 insertions(+), 10 deletions(-) diff --git a/src/bin/lttng-sessiond/notification-thread-events.c b/src/bin/lttng-sessiond/notification-thread-events.c index 2cb6ad68a..7b86fb39c 100644 --- a/src/bin/lttng-sessiond/notification-thread-events.c +++ b/src/bin/lttng-sessiond/notification-thread-events.c @@ -2564,8 +2564,7 @@ int client_flush_outgoing_queue(struct notification_client *client, ret = lttcomm_send_unix_sock_non_block(client->socket, client->communication.outbound.buffer.data, to_send_count); - if ((ret < 0 && (errno == EAGAIN || errno == EWOULDBLOCK)) || - (ret > 0 && ret < to_send_count)) { + if ((ret >= 0 && ret < to_send_count)) { DBG("[notification-thread] Client (socket fd = %i) outgoing queue could not be completely flushed", client->socket); to_send_count -= max(ret, 0); diff --git a/src/common/unix.c b/src/common/unix.c index 26eda52d9..df92b7a06 100644 --- a/src/common/unix.c +++ b/src/common/unix.c @@ -210,6 +210,9 @@ ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len) * Receive data of size len in put that data into the buf param. Using recvmsg * API. Only use with sockets set in non-blocking mode. * + * NOTE: EPIPE errors are NOT reported. This call expects the socket to be in a + * poll set. The poll loop will handle the EPIPE original cause. + * * Return the size of received data. */ LTTNG_HIDDEN @@ -232,11 +235,21 @@ retry: if (errno == EINTR) { goto retry; } else { - /* We consider EPIPE and EAGAIN as expected. */ - if (!lttng_opt_quiet && - (errno != EPIPE && errno != EAGAIN)) { - PERROR("recvmsg"); + /* + * We consider EPIPE and EAGAIN/EWOULDBLOCK as expected. + */ + if (errno == EAGAIN || errno == EWOULDBLOCK || + errno == EPIPE) { + /* + * Nothing was recv. + */ + ret = 0; + goto end; } + + /* Unexpected error */ + PERROR("recvmsg"); + ret = -1; goto end; } } @@ -295,6 +308,9 @@ end: * of the function is that this one does not retry to send on partial sends, * except if the interruption was caused by a signal (EINTR). * + * NOTE: EPIPE errors are NOT reported. This call expects the socket to be in a + * poll set. The poll loop will handle the EPIPE original cause. + * * Return the size of sent data. */ LTTNG_HIDDEN @@ -317,11 +333,22 @@ retry: if (errno == EINTR) { goto retry; } else { - /* We consider EPIPE and EAGAIN as expected. */ - if (!lttng_opt_quiet && - (errno != EPIPE && errno != EAGAIN)) { - PERROR("sendmsg"); + /* + * We consider EPIPE and EAGAIN/EWOULDBLOCK as expected. + */ + if (errno == EAGAIN || errno == EWOULDBLOCK || + errno == EPIPE) { + /* + * This can happen in non blocking mode. + * Nothing was sent. + */ + ret = 0; + goto end; } + + /* Unexpected error */ + PERROR("sendmsg"); + ret = -1; goto end; } } -- 2.34.1