From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 23 May 2014 13:26:11 +0000 (-0400)
Subject: Fix: refuse overwrite mode buffers with less than two subbuffers
X-Git-Tag: v2.5.0-rc1~2
X-Git-Url: http://git.lttng.org/?p=lttng-modules.git;a=commitdiff_plain;h=5140d2b3070f211e6d8a0ad7cb0a190e8b6f3e28

Fix: refuse overwrite mode buffers with less than two subbuffers

Fixes #793

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

diff --git a/lib/ringbuffer/ring_buffer_backend.c b/lib/ringbuffer/ring_buffer_backend.c
index f7ed20df..3cc22d77 100644
--- a/lib/ringbuffer/ring_buffer_backend.c
+++ b/lib/ringbuffer/ring_buffer_backend.c
@@ -331,6 +331,12 @@ int channel_backend_init(struct channel_backend *chanb,
 		return -EINVAL;
 	if (!num_subbuf || (num_subbuf & (num_subbuf - 1)))
 		return -EINVAL;
+	/*
+	 * Overwrite mode buffers require at least 2 subbuffers per
+	 * buffer.
+	 */
+	if (config->mode == RING_BUFFER_OVERWRITE && num_subbuf < 2)
+		return -EINVAL;
 
 	ret = subbuffer_id_check_index(config, num_subbuf);
 	if (ret)