From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 26 Jun 2013 17:55:31 +0000 (-0400)
Subject: Fix: don't do 0 byte event reservation
X-Git-Tag: v2.3.0-rc1~22
X-Git-Url: http://git.lttng.org/?p=lttng-modules.git;a=commitdiff_plain;h=9de2c21569afcb6b983e81a2e9b1d0c2b83c98f0

Fix: don't do 0 byte event reservation

Caused sequence of:

lttng create
lttng enable-event -k sched_switch
lttng start
lttng stop
lttng start
lttng stop

to hang on waiting for data......

Issue appeared in

commit d83004aa718065e5221d8ef4b99e4302b70b3df9
Author: Julien Desfossez <jdesfossez@efficios.com>
Date:   Thu Jun 6 16:38:48 2013 -0400

    Metadata cache and multiple metadata channels

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

diff --git a/lttng-events.c b/lttng-events.c
index faf3e1f0..27a8f864 100644
--- a/lttng-events.c
+++ b/lttng-events.c
@@ -563,6 +563,8 @@ int lttng_metadata_output_channel(struct lttng_channel *chan,
 
 	len = stream->metadata_cache->metadata_written -
 		stream->metadata_cache_read;
+	if (!len)
+		return 0;
 	reserve_len = min_t(size_t,
 			chan->ops->packet_avail_size(chan->chan),
 			len);