[PATCH 02/11] staging: comedi: comedi_buf: factor out common comedi_buf_write_alloc_* code

H Hartley Sweeten hsweeten at visionengravers.com
Fri Dec 21 16:37:19 UTC 2012


The only difference between comedi_but_write_alloc() and the *_strict()
version is that the *_strick() one will only allocate the chuck if it
can completely fulfill the request.

Factor out the common code and add a flag parameter to indicate the 'strict'
usage. Change the exported functions so they are just wrappers around the
common function.

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 | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
index fe2dcae..838f089 100644
--- a/drivers/staging/comedi/comedi_buf.c
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -191,14 +191,18 @@ unsigned int comedi_buf_write_n_available(struct comedi_async *async)
 	return nbytes;
 }
 
-/* allocates chunk for the writer from free buffer space */
-unsigned int comedi_buf_write_alloc(struct comedi_async *async,
-				    unsigned int nbytes)
+static unsigned int __comedi_buf_write_alloc(struct comedi_async *async,
+					     unsigned int nbytes,
+					     int strict)
 {
 	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
 
-	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)
-		nbytes = free_end - async->buf_write_alloc_count;
+	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0) {
+		if (strict)
+			nbytes = 0;
+		else
+			nbytes = free_end - async->buf_write_alloc_count;
+	}
 
 	async->buf_write_alloc_count += nbytes;
 	/* barrier insures the read of buf_read_count above occurs before
@@ -206,22 +210,20 @@ unsigned int comedi_buf_write_alloc(struct comedi_async *async,
 	smp_mb();
 	return nbytes;
 }
+
+/* allocates chunk for the writer from free buffer space */
+unsigned int comedi_buf_write_alloc(struct comedi_async *async,
+				    unsigned int nbytes)
+{
+	return __comedi_buf_write_alloc(async, nbytes, 0);
+}
 EXPORT_SYMBOL(comedi_buf_write_alloc);
 
 /* allocates nothing unless it can completely fulfill the request */
 unsigned int comedi_buf_write_alloc_strict(struct comedi_async *async,
 					   unsigned int nbytes)
 {
-	unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
-
-	if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)
-		nbytes = 0;
-
-	async->buf_write_alloc_count += nbytes;
-	/* barrier insures the read of buf_read_count above occurs before
-	   we write data to the write-alloc'ed buffer space */
-	smp_mb();
-	return nbytes;
+	return __comedi_buf_write_alloc(async, nbytes, 1);
 }
 
 /* munging is applied to data by core as it passes between user
-- 
1.8.0




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