From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 2 Mar 2012 16:54:13 +0000 (-0500)
Subject: Fix: incorrect close of fd 0 for syscall kernel event destroy
X-Git-Tag: v2.0.0-rc2~14
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=87eb4ab891dda35c54ffa95f356a4c4b198d8716

Fix: incorrect close of fd 0 for syscall kernel event destroy

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

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index 371ee4f98..2936406d8 100644
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -208,6 +208,11 @@ int kernel_create_event(struct lttng_event *ev,
 	 */
 	if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
 		DBG2("Kernel event syscall creation success");
+		/*
+		 * We use fd == -1 to ensure that we never trigger a close of fd
+		 * 0.
+		 */
+		event->fd = -1;
 		goto add_list;
 	}
 
diff --git a/src/bin/lttng-sessiond/trace-kernel.c b/src/bin/lttng-sessiond/trace-kernel.c
index 36f7c9708..68753286f 100644
--- a/src/bin/lttng-sessiond/trace-kernel.c
+++ b/src/bin/lttng-sessiond/trace-kernel.c
@@ -321,9 +321,13 @@ void trace_kernel_destroy_stream(struct ltt_kernel_stream *stream)
  */
 void trace_kernel_destroy_event(struct ltt_kernel_event *event)
 {
-	DBG("[trace] Closing event fd %d", event->fd);
-	/* Close kernel fd */
-	close(event->fd);
+	if (event->fd >= 0) {
+		DBG("[trace] Closing event fd %d", event->fd);
+		/* Close kernel fd */
+		close(event->fd);
+	} else {
+		DBG("[trace] Tearing down event (no associated fd)");
+	}
 
 	/* Remove from event list */
 	cds_list_del(&event->list);