[PATCH 4/5] 9p: virtio: skip incrementing unused variable

Dominique Martinet posted 5 patches 2 years, 9 months ago
There is a newer version of this series
[PATCH 4/5] 9p: virtio: skip incrementing unused variable
Posted by Dominique Martinet 2 years, 9 months ago
Fix the following scan-build warning:
net/9p/trans_virtio.c:504:3: warning: Value stored to 'in' is never read [deadcode.DeadStores]
                in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
                ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I'm honestly not 100% sure about this one; I'm tempted to think we
could (should?) just check the return value of pack_sg_list_p to skip
the in_sgs++ and setting sgs[] if it didn't process anything, but I'm
not sure it should ever happen so this is probably fine as is.

Just removing the assignment at least makes it clear the return value
isn't used, so it's an improvement in terms of readability.

Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
---
 net/9p/trans_virtio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index f3f678289423..e305071eb7b8 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -501,8 +501,8 @@ p9_virtio_zc_request(struct p9_client *client, struct p9_req_t *req,
 
 	if (in_pages) {
 		sgs[out_sgs + in_sgs++] = chan->sg + out + in;
-		in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
-				     in_pages, in_nr_pages, offs, inlen);
+		pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
+			       in_pages, in_nr_pages, offs, inlen);
 	}
 
 	BUG_ON(out_sgs + in_sgs > ARRAY_SIZE(sgs));

-- 
2.39.2
Re: [PATCH 4/5] 9p: virtio: skip incrementing unused variable
Posted by Simon Horman 2 years, 9 months ago
On Thu, Apr 27, 2023 at 08:23:37PM +0900, Dominique Martinet wrote:
> Fix the following scan-build warning:
> net/9p/trans_virtio.c:504:3: warning: Value stored to 'in' is never read [deadcode.DeadStores]
>                 in += pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
>                 ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> I'm honestly not 100% sure about this one; I'm tempted to think we
> could (should?) just check the return value of pack_sg_list_p to skip
> the in_sgs++ and setting sgs[] if it didn't process anything, but I'm
> not sure it should ever happen so this is probably fine as is.
> 
> Just removing the assignment at least makes it clear the return value
> isn't used, so it's an improvement in terms of readability.
> 
> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>

Reviewed-by: Simon Horman <simon.horman@corigine.com>