From: Julien Desfossez <jdesfossez@efficios.com>
Date: Mon, 11 Dec 2017 21:11:09 +0000 (-0500)
Subject: Fix: kernel snapshot handling of EAGAIN
X-Git-Tag: v2.9.9~7
X-Git-Url: http://git.liburcu.org/?p=lttng-tools.git;a=commitdiff_plain;h=ee6bb36a4235a005b7d674f341f50c10b2ae52aa

Fix: kernel snapshot handling of EAGAIN

kernctl_snapshot can return EAGAIN, this is not an error, it only means
there is no data to read.

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

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 1079047f0..0afa143a5 100644
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -60,7 +60,11 @@ int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
 	int infd = stream->wait_fd;
 
 	ret = kernctl_snapshot(infd);
-	if (ret != 0) {
+	/*
+	 * -EAGAIN is not an error, it just means that there is no data to
+	 *  be read.
+	 */
+	if (ret != 0 && ret != -EAGAIN) {
 		PERROR("Getting sub-buffer snapshot.");
 	}