Remove MSG_WAITALL on every recvmsg() socket type

In order to handle messages that are possibly larger than the socket
buffer size set by wmem_max and rmem_max /proc files, ensure that the
recv-side reads the data chunk-wise rather than hanging on a
MSG_WAITALL.

In addition to fixing this issue, chances are that it will also help
fixing hangs detected due to UNIX socket buffers filling up. The
MSG_WAITALL behavior in such situations might be unexpected.

Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>

diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index bd19a323715309697ba3b3ff61c6d29a615ad379..2a7152b892192f7e683bf881b2b106af0a2da36c 100644 (file)
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -932,7 +932,7 @@ int relay_add_stream(struct lttcomm_relayd_hdr *recv_hdr,
 
        /* FIXME : use data_size for something ? */
        ret = cmd->sock->ops->recvmsg(cmd->sock, &stream_info,
-                       sizeof(struct lttcomm_relayd_add_stream), MSG_WAITALL);
+                       sizeof(struct lttcomm_relayd_add_stream), 0);
        if (ret < sizeof(struct lttcomm_relayd_add_stream)) {
                ERR("Relay didn't receive valid add_stream struct size : %d", ret);
                ret = -1;
@@ -1028,7 +1028,7 @@ int relay_close_stream(struct lttcomm_relayd_hdr *recv_hdr,
        }
 
        ret = cmd->sock->ops->recvmsg(cmd->sock, &stream_info,
-                       sizeof(struct lttcomm_relayd_close_stream), MSG_WAITALL);
+                       sizeof(struct lttcomm_relayd_close_stream), 0);
        if (ret < sizeof(struct lttcomm_relayd_close_stream)) {
                ERR("Relay didn't receive valid add_stream struct size : %d", ret);
                ret = -1;
@@ -1232,8 +1232,7 @@ int relay_recv_metadata(struct lttcomm_relayd_hdr *recv_hdr,
        }
        memset(data_buffer, 0, data_size);
        DBG2("Relay receiving metadata, waiting for %" PRIu64 " bytes", data_size);
-       ret = cmd->sock->ops->recvmsg(cmd->sock, data_buffer, data_size,
-                       MSG_WAITALL);
+       ret = cmd->sock->ops->recvmsg(cmd->sock, data_buffer, data_size, 0);
        if (ret < 0 || ret != data_size) {
                ret = -1;
                ERR("Relay didn't receive the whole metadata");
@@ -1300,7 +1299,7 @@ int relay_send_version(struct lttcomm_relayd_hdr *recv_hdr,
        session->version_check_done = 1;
 
        /* Get version from the other side. */
-       ret = cmd->sock->ops->recvmsg(cmd->sock, &msg, sizeof(msg), MSG_WAITALL);
+       ret = cmd->sock->ops->recvmsg(cmd->sock, &msg, sizeof(msg), 0);
        if (ret < 0 || ret != sizeof(msg)) {
                ret = -1;
                ERR("Relay failed to receive the version values.");
@@ -1358,7 +1357,7 @@ int relay_data_pending(struct lttcomm_relayd_hdr *recv_hdr,
                goto end_no_session;
        }
 
-       ret = cmd->sock->ops->recvmsg(cmd->sock, &msg, sizeof(msg), MSG_WAITALL);
+       ret = cmd->sock->ops->recvmsg(cmd->sock, &msg, sizeof(msg), 0);
        if (ret < sizeof(msg)) {
                ERR("Relay didn't receive valid data_pending struct size : %d", ret);
                ret = -1;
@@ -1493,7 +1492,7 @@ int relay_process_data(struct relay_command *cmd, struct lttng_ht *streams_ht)
        uint32_t data_size;
 
        ret = cmd->sock->ops->recvmsg(cmd->sock, &data_hdr,
-                       sizeof(struct lttcomm_relayd_data_hdr), MSG_WAITALL);
+                       sizeof(struct lttcomm_relayd_data_hdr), 0);
        if (ret <= 0) {
                ERR("Connections seems to be closed");
                ret = -1;
@@ -1527,7 +1526,7 @@ int relay_process_data(struct relay_command *cmd, struct lttng_ht *streams_ht)
 
        DBG3("Receiving data of size %u for stream id %" PRIu64 " seqnum %" PRIu64,
                data_size, stream_id, net_seq_num);
-       ret = cmd->sock->ops->recvmsg(cmd->sock, data_buffer, data_size, MSG_WAITALL);
+       ret = cmd->sock->ops->recvmsg(cmd->sock, data_buffer, data_size, 0);
        if (ret <= 0) {
                ret = -1;
                goto end_unlock;
@@ -1767,7 +1766,7 @@ void *relay_thread_worker(void *data)
                                        if (relay_connection->type == RELAY_CONTROL) {
                                                ret = relay_connection->sock->ops->recvmsg(
                                                                relay_connection->sock, &recv_hdr,
-                                                               sizeof(struct lttcomm_relayd_hdr), MSG_WAITALL);
+                                                               sizeof(struct lttcomm_relayd_hdr), 0);
                                                /* connection closed */
                                                if (ret <= 0) {
                                                        relay_cleanup_poll_connection(&events, pollfd);

diff --git a/src/common/sessiond-comm/inet.c b/src/common/sessiond-comm/inet.c
index f9ea17dbf975b246448e463b69ff64978745c9bc..7aee725602f1441f72093cc42ffdac7e16257117 100644 (file)
--- a/src/common/sessiond-comm/inet.c
+++ b/src/common/sessiond-comm/inet.c
@@ -207,6 +207,7 @@ ssize_t lttcomm_recvmsg_inet_sock(struct lttcomm_sock *sock, void *buf,
        struct msghdr msg;
        struct iovec iov[1];
        ssize_t ret = -1;
+       size_t len_last;
 
        memset(&msg, 0, sizeof(msg));
 
@@ -218,16 +219,21 @@ ssize_t lttcomm_recvmsg_inet_sock(struct lttcomm_sock *sock, void *buf,
        msg.msg_name = (struct sockaddr *) &sock->sockaddr.addr.sin;
        msg.msg_namelen = sizeof(sock->sockaddr.addr.sin);
 
-       if (flags == 0) {
-               flags = MSG_WAITALL;
-       }
-
        do {
+               len_last = iov[0].iov_len;
                ret = recvmsg(sock->fd, &msg, flags);
-       } while (ret < 0 && errno == EINTR);
+               if (ret > 0) {
+                       iov[0].iov_base += ret;
+                       iov[0].iov_len -= ret;
+                       assert(ret <= len_last);
+               }
+       } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
        if (ret < 0) {
                PERROR("recvmsg inet");
+       } else if (ret > 0) {
+               ret = len;
        }
+       /* Else ret = 0 meaning an orderly shutdown. */
 
        return ret;
 }

diff --git a/src/common/sessiond-comm/inet6.c b/src/common/sessiond-comm/inet6.c
index 024beace3bed4ff8dc704936317ebc546540a1b9..ddbb50ed43aa96dc94b6f2fe4b8201c4925b8c5c 100644 (file)
--- a/src/common/sessiond-comm/inet6.c
+++ b/src/common/sessiond-comm/inet6.c
@@ -207,6 +207,7 @@ ssize_t lttcomm_recvmsg_inet6_sock(struct lttcomm_sock *sock, void *buf,
        struct msghdr msg;
        struct iovec iov[1];
        ssize_t ret = -1;
+       size_t len_last;
 
        memset(&msg, 0, sizeof(msg));
 
@@ -218,16 +219,21 @@ ssize_t lttcomm_recvmsg_inet6_sock(struct lttcomm_sock *sock, void *buf,
        msg.msg_name = (struct sockaddr *) &sock->sockaddr.addr.sin6;
        msg.msg_namelen = sizeof(sock->sockaddr.addr.sin6);
 
-       if (flags == 0) {
-               flags = MSG_WAITALL;
-       }
-
        do {
+               len_last = iov[0].iov_len;
                ret = recvmsg(sock->fd, &msg, flags);
-       } while (ret < 0 && errno == EINTR);
+               if (ret > 0) {
+                       iov[0].iov_base += ret;
+                       iov[0].iov_len -= ret;
+                       assert(ret <= len_last);
+               }
+       } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
        if (ret < 0) {
-               PERROR("recvmsg inet6");
+               PERROR("recvmsg inet");
+       } else if (ret > 0) {
+               ret = len;
        }
+       /* Else ret = 0 meaning an orderly shutdown. */
 
        return ret;
 }

diff --git a/src/common/sessiond-comm/unix.c b/src/common/sessiond-comm/unix.c
index 2f79f3a280a123bd85a861ff039f72e5e4c6064c..bbf030f67f6bc0cef88b956af83da132f548bd57 100644 (file)
--- a/src/common/sessiond-comm/unix.c
+++ b/src/common/sessiond-comm/unix.c
@@ -157,6 +157,7 @@ ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
        struct msghdr msg;
        struct iovec iov[1];
        ssize_t ret = -1;
+       size_t len_last;
 
        memset(&msg, 0, sizeof(msg));
 
@@ -166,11 +167,20 @@ ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
        msg.msg_iovlen = 1;
 
        do {
-               ret = recvmsg(sock, &msg, MSG_WAITALL);
-       } while (ret < 0 && errno == EINTR);
+               len_last = iov[0].iov_len;
+               ret = recvmsg(sock, &msg, 0);
+               if (ret > 0) {
+                       iov[0].iov_base += ret;
+                       iov[0].iov_len -= ret;
+                       assert(ret <= len_last);
+               }
+       } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
        if (ret < 0) {
                PERROR("recvmsg");
+       } else if (ret > 0) {
+               ret = len;
        }
+       /* Else ret = 0 meaning an orderly shutdown. */
 
        return ret;
 }