staging: comedi: comedi_buf: cleanup comedi_buf_read_n_available()

For aesthetic reasons, cleanup this function a bit.

Change the (async == NULL) test to simply (!async).

Reword the comment about the need for the smp_rmb()..

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
index fd2a92e..06dd544 100644 (file)
--- a/drivers/staging/comedi/comedi_buf.c
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -273,14 +273,17 @@ unsigned int comedi_buf_read_n_available(struct comedi_async *async)
 {
        unsigned num_bytes;
 
-       if (async == NULL)
+       if (!async)
                return 0;
+
        num_bytes = async->munge_count - async->buf_read_count;
-       /* barrier insures the read of munge_count in this
-          query occurs before any following reads of the buffer which
-          might be based on the return value from this query.
+
+       /*
+        * ensure the async buffer 'counts' are read before we
+        * attempt to read data from the buffer
         */
        smp_rmb();
+
        return num_bytes;
 }
 EXPORT_SYMBOL(comedi_buf_read_n_available);