From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 13 Sep 2016 20:17:04 +0000 (-0400)
Subject: Fix: honor send timeout on unix socket connect
X-Git-Tag: v2.7.5~5
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=27d8df8abdd6b40203be18365146889d88a28e11;p=lttng-ust.git

Fix: honor send timeout on unix socket connect

Needed if we want to hold the ust_lock() while we connect to the session
daemon without blocking the application forever if the session daemon is
hung on SIGSTOP.

This only triggers if we launchs _many_ applications with a session
daemon SIGSTOP'd (e.g. 1000 in parallel), so we fill the socket queue,
and applications hang there until the session daemon is SIGCONT'd.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/include/ust-comm.h b/include/ust-comm.h
index b9bbb39b..1fb5796f 100644
--- a/include/ust-comm.h
+++ b/include/ust-comm.h
@@ -170,7 +170,8 @@ struct ustcomm_notify_channel_reply {
  */
 
 extern int ustcomm_create_unix_sock(const char *pathname);
-extern int ustcomm_connect_unix_sock(const char *pathname);
+extern int ustcomm_connect_unix_sock(const char *pathname,
+		long timeout);
 extern int ustcomm_accept_unix_sock(int sock);
 extern int ustcomm_listen_unix_sock(int sock);
 extern int ustcomm_close_unix_sock(int sock);
diff --git a/liblttng-ust-comm/lttng-ust-comm.c b/liblttng-ust-comm/lttng-ust-comm.c
index cee1b694..d065499a 100644
--- a/liblttng-ust-comm/lttng-ust-comm.c
+++ b/liblttng-ust-comm/lttng-ust-comm.c
@@ -86,7 +86,7 @@ const char *lttng_ust_strerror(int code)
  *
  * Connect to unix socket using the path name.
  */
-int ustcomm_connect_unix_sock(const char *pathname)
+int ustcomm_connect_unix_sock(const char *pathname, long timeout)
 {
 	struct sockaddr_un sun;
 	int fd, ret;
@@ -101,6 +101,15 @@ int ustcomm_connect_unix_sock(const char *pathname)
 		ret = -errno;
 		goto error;
 	}
+	if (timeout >= 0) {
+		/* Give at least 10ms. */
+		if (timeout < 10)
+			timeout = 10;
+		ret = ustcomm_setsockopt_snd_timeout(fd, timeout);
+		if (ret < 0) {
+			WARN("Error setting connect socket send timeout");
+		}
+	}
 	ret = fcntl(fd, F_SETFD, FD_CLOEXEC);
 	if (ret < 0) {
 		PERROR("fcntl");
diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 373a1c2d..335279fb 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -433,7 +433,7 @@ int setup_local_apps(void)
 }
 
 /*
- * Get notify_sock timeout, in ms.
+ * Get socket timeout, in ms.
  * -1: wait forever. 0: don't wait. >0: timeout, in ms.
  */
 static
@@ -453,12 +453,20 @@ long get_timeout(void)
 	return constructor_delay_ms;
 }
 
+/* Timeout for notify socket send and recv. */
 static
 long get_notify_sock_timeout(void)
 {
 	return get_timeout();
 }
 
+/* Timeout for connecting to cmd and notify sockets. */
+static
+long get_connect_sock_timeout(void)
+{
+	return get_timeout();
+}
+
 /*
  * Return values: -1: wait forever. 0: don't wait. 1: timeout wait.
  */
@@ -1274,7 +1282,8 @@ restart:
 	 * first connect registration message.
 	 */
 	/* Connect cmd socket */
-	ret = ustcomm_connect_unix_sock(sock_info->sock_path);
+	ret = ustcomm_connect_unix_sock(sock_info->sock_path,
+		get_connect_sock_timeout());
 	if (ret < 0) {
 		DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
 		prev_connect_failed = 1;
@@ -1330,7 +1339,8 @@ restart:
 	ust_unlock();
 
 	/* Connect notify socket */
-	ret = ustcomm_connect_unix_sock(sock_info->sock_path);
+	ret = ustcomm_connect_unix_sock(sock_info->sock_path,
+		get_connect_sock_timeout());
 	if (ret < 0) {
 		DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
 		prev_connect_failed = 1;