From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Thu, 24 Sep 2015 16:34:49 +0000 (-0400)
Subject: Fix: Handle EINTR of waitpid when spawning a session daemon
X-Git-Tag: v2.8.0-rc1~300
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=81527d36f84a02110360f0332f3b35f2d3024d17;hp=034a784813438dd99cfd1c1ea2fc9ee713dad345;ds=sidebyside

Fix: Handle EINTR of waitpid when spawning a session daemon

waitpid may fail for various reasons, being interrupted being
the most frequent. In such a case, status is left uninitialized
which results in the WIFSIGNALED and WIFEXITED macros returning
undefined value, resulting in surprising logging statements such
as "killed by signal 114".

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/bin/lttng/commands/create.c b/src/bin/lttng/commands/create.c
index a7d327fbc..abc5cb9b8 100644
--- a/src/bin/lttng/commands/create.c
+++ b/src/bin/lttng/commands/create.c
@@ -579,14 +579,22 @@ static int spawn_sessiond(char *pathname)
 		kill(getppid(), SIGTERM);	/* wake parent */
 		exit(EXIT_FAILURE);
 	} else if (pid > 0) {
-		int status;
-
 		/*
 		 * In daemon mode (--daemonize), sessiond only exits when
 		 * it's ready to accept commands.
 		 */
 		for (;;) {
-			waitpid(pid, &status, 0);
+			int status;
+			pid_t wait_pid_ret = waitpid(pid, &status, 0);
+
+			if (wait_pid_ret < 0) {
+				if (errno == EINTR) {
+					continue;
+				}
+				PERROR("waitpid");
+				ret = -errno;
+				goto end;
+			}
 
 			if (WIFSIGNALED(status)) {
 				ERR("Session daemon was killed by signal %d",