[PATCH net-next] netlink: gc useless variable in nlmsg_attrdata()

Kernel permits pointer arithmetic on "void*" so might as well use it
without casts back and forth.

Signed-off-by: Alexey Dobriyan <redacted>
---

 include/net/netlink.h |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/include/net/netlink.h
+++ b/include/net/netlink.h

@@ -587,8 +587,7 @@ static inline int nlmsg_len(const struct nlmsghdr *nlh)
 static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
 					    int hdrlen)
 {
-	unsigned char *data = nlmsg_data(nlh);
-	return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
+	return nlmsg_data(nlh) + NLMSG_ALIGN(hdrlen);
 }
 
 /**

On Fri, 13 Aug 2021 00:24:01 +0300 Alexey Dobriyan wrote:

Kernel permits pointer arithmetic on "void*" so might as well use it
without casts back and forth.

But why change existing code? It's perfectly fine, right?

On Thu, Aug 12, 2021 at 03:05:52PM -0700, Jakub Kicinski wrote:

On Fri, 13 Aug 2021 00:24:01 +0300 Alexey Dobriyan wrote:

quoted

Kernel permits pointer arithmetic on "void*" so might as well use it
without casts back and forth.

But why change existing code? It's perfectly fine, right?

It is harder to read (marginally of course).

quoted

--- a/include/net/netlink.h
+++ b/include/net/netlink.h

@@ -587,8 +587,7 @@ static inline int nlmsg_len(const struct nlmsghdr *nlh)
 static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
 					    int hdrlen)
 {
-	unsigned char *data = nlmsg_data(nlh);
-	return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
+	return nlmsg_data(nlh) + NLMSG_ALIGN(hdrlen);
 }
 
 /**

On Fri, 13 Aug 2021 08:27:30 +0300 Alexey Dobriyan wrote:

On Thu, Aug 12, 2021 at 03:05:52PM -0700, Jakub Kicinski wrote:

quoted

On Fri, 13 Aug 2021 00:24:01 +0300 Alexey Dobriyan wrote:  

quoted

Kernel permits pointer arithmetic on "void*" so might as well use it
without casts back and forth.  

But why change existing code? It's perfectly fine, right?  

It is harder to read (marginally of course).

TBH I prefer the current code, I don't have to wonder what type
nlmsg_data() returns and whether it's okay to do void* arithmetic 
in this header (if it's uAPI). Sorry :(