On Thu, Apr 11, 2024 at 11:04:15AM +0000, Tung Quang Nguyen wrote:
> >Subject: Re: [PATCH][next] tipc: remove redundant assignment to ret, simplify code
> >
> >On 11/04/2024 11:31, Dan Carpenter wrote:
> >> On Thu, Apr 11, 2024 at 10:04:10AM +0000, Tung Quang Nguyen wrote:
> >>>>
> >>> I suggest that err variable should be completely removed. Could you
> >>> please also do the same thing for this code ?
> >>> "
> >>> ...
> >>> err = skb_handler(skb, cb, tsk);
> >>> if (err) {
> >>
> >> If we write the code as:
> >>
> >> if (some_function(parameters)) {
> >>
> >> then at first that looks like a boolean. People probably think the
> >> function returns true/false. But if we leave it as-is:
> >>
> >> err = some_function(parameters);
> >> if (err) {
> >>
> >> Then that looks like error handling.
> >>
> >> So it's better and more readable to leave it as-is.
> >>
> >> regards,
> >> dan carpenter
> >
> >I concur with Dan's comments.
> >
> >Colin
> I have a different view.
> It does not make sense to me to use stack variable 'err' just for
> checking return code of the functions (__tipc_nl_add_sk/
> __tipc_add_sock_diag) that we know always return true on error.
>
I think you are trying to mirco optimize the code at the expense
of readability. It is unnecessary. The compiler is smart enough to
generate the same code either way. I have just tested this on my system
and it is true.
$ md5sum net/tipc/socket.o.*
f5ebea97eeb9736c5b8097158c2b12e5 net/tipc/socket.o.without_var
f5ebea97eeb9736c5b8097158c2b12e5 net/tipc/socket.o.with_var
$
When you're doing these tests, you need to ensure that the line numbers
do change so I have commented out the old lines instead of deleting
them.
regards,
dan carpenter
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 7e4135db5816..879a8a9786b0 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -3560,24 +3560,21 @@ int tipc_nl_sk_walk(struct sk_buff *skb, struct netlink_callback *cb,
{
struct rhashtable_iter *iter = (void *)cb->args[4];
struct tipc_sock *tsk;
- int err;
+// int err;
rhashtable_walk_start(iter);
while ((tsk = rhashtable_walk_next(iter)) != NULL) {
if (IS_ERR(tsk)) {
- err = PTR_ERR(tsk);
- if (err == -EAGAIN) {
- err = 0;
+ if (PTR_ERR(tsk) == -EAGAIN)
continue;
- }
break;
}
sock_hold(&tsk->sk);
rhashtable_walk_stop(iter);
lock_sock(&tsk->sk);
- err = skb_handler(skb, cb, tsk);
- if (err) {
+// err = skb_handler(skb, cb, tsk);
+ if (skb_handler(skb, cb, tsk)) {
release_sock(&tsk->sk);
sock_put(&tsk->sk);
goto out;
