On 2013-05-10 17:27, H Hartley Sweeten wrote:
On Friday, May 10, 2013 6:07 AM, Ian Abbott wrote:
When allocating a buffer to support asynchronous comedi commands, if a
DMA coherent buffer was requested but `CONFIG_HAS_DMA` is undefined,
bail out of local helper function `__comedi_buf_alloc()` with an error
message.
Signed-off-by: Ian Abbott <abbo...@mev.co.uk>
---
drivers/staging/comedi/comedi_buf.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/staging/comedi/comedi_buf.c
b/drivers/staging/comedi/comedi_buf.c
index b6cd67a..d4be0e6 100644
--- a/drivers/staging/comedi/comedi_buf.c
+++ b/drivers/staging/comedi/comedi_buf.c
@@ -76,6 +76,12 @@ static void __comedi_buf_alloc(struct comedi_device *dev,
struct comedi_buf_page *buf;
unsigned i;
+ if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) {
+ dev_err(dev->class_dev,
+ "dma buffer allocation not supported\n");
+ return;
+ }
+
async->buf_page_list = vzalloc(sizeof(*buf) * n_pages);
if (async->buf_page_list)
pages = vmalloc(sizeof(struct page *) * n_pages);
Would it be better to put this test in comedi_buf_alloc() and return a different
errno?
With the check in __comedi_buf_alloc(), comedi_buf_alloc() needlessly calls
__comedi_buf_free() and __comedi_buf_alloc() before returning an errno of
-ENOMEM. I think an errno of -ENOSYS, or even -EINVAL, would be more
appropriate.
What would a fake dma_alloc_coherent() inline stub function return if it
existed? I think it might return -ENOMEM. Since __comedi_buf_alloc()
is only called from comedi_buf_alloc() and could easily be changed to
return an errno, I don't think it matters where the test is done.
--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbo...@mev.co.uk> )=-
-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
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