[PATCH 07/11] staging: comedi: comedi_buf: clarify comedi_buf_write_free()

H Hartley Sweeten hsweeten at visionengravers.com
Fri Dec 21 16:41:19 UTC 2012


Clarify the check to make sure the number of bytes to free is not
more than the number of bytes allocated.

Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
Cc: Ian Abbott <abbobbi at mev.co.uk>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/staging/comedi/comedi_buf.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
index 60acb73..5e08266 100644
--- a/drivers/staging/comedi/comedi_buf.c
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -262,11 +262,12 @@ static unsigned int comedi_buf_munge(struct comedi_async *async,
 /* transfers a chunk from writer to filled buffer space */
 unsigned comedi_buf_write_free(struct comedi_async *async, unsigned int nbytes)
 {
-	if ((int)(async->buf_write_count + nbytes -
-		  async->buf_write_alloc_count) > 0) {
+	unsigned allocated = comedi_buf_write_n_allocated(async);
+
+	if (nbytes > allocated) {
 		dev_info(async->subdevice->device->class_dev,
 			 "attempted to write-free more bytes than have been write-allocated.\n");
-		nbytes = async->buf_write_alloc_count - async->buf_write_count;
+		nbytes = allocated;
 	}
 	async->buf_write_count += nbytes;
 	async->buf_write_ptr += nbytes;
-- 
1.8.0




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