The only difference between comedi_buf_write_alloc() and the *_strict()
version is that the *_strict() one will only allocate the chunk 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.
Cleanup the common function a bit and use the comedi_buf_write_n_available()
helper to determine the number of bytes available.
Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Cc: Ian Abbott <abbobbi@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/comedi/comedi_buf.c | 33 ++++++++++++++-------------------
1 file changed, 14 insertions(+), 19 deletions(-)
diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c
index a6b22c5..56793d0 100644
--- a/drivers/staging/comedi/comedi_buf.c
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -196,37 +196,32 @@ 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;
+ unsigned int available = comedi_buf_write_n_available(async);
- if ((int)(async->buf_write_alloc_count + nbytes - free_end) > 0)
- nbytes = free_end - async->buf_write_alloc_count;
+ if (nbytes > available)
+ nbytes = strict ? 0 : available;
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;
}
+
+/* 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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