ring-buffer: check for less than two in size allocation

The ring buffer must have at least two pages allocated for the
reader page swap to work.

The page count check will miss the case of a zero size passed in.
Even though a zero size ring buffer would probably fail an allocation,
making the min size check for less than two instead of equal to one makes
the code a bit more robust.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 162da2305cbcc321d3f939baccb03962f6878b97..2e99dba6dc48cdff7041d80055dfce68fe6c0849 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -657,8 +657,8 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
        buffer->reader_lock_key = key;
 
        /* need at least two pages */
-       if (buffer->pages == 1)
-               buffer->pages++;
+       if (buffer->pages < 2)
+               buffer->pages = 2;
 
        /*
         * In case of non-hotplug cpu, if the ring-buffer is allocated