[PATCH] net: ipv4: remove redundant initialization in inet_rtm_deladdr

[PATCH] net: ipv4: remove redundant initialization in inet_rtm_deladdr

[menglong8.dong]

From: Menglong Dong <dong.menglong@zte.com.cn>

The initialization for 'err' with '-EINVAL' is redundant and
can be removed, as it is updated soon.

Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
---
 net/ipv4/devinet.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 123a6d3..847cb18 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -651,7 +651,7 @@ static int inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct ifaddrmsg *ifm;
 	struct in_ifaddr *ifa;
 
-	int err = -EINVAL;
+	int err;
 
 	ASSERT_RTNL();
 
-- 
2.7.4

[PATCH] net: udp: remove redundant initialization in udp_dump_one

[menglong8.dong]

From: Menglong Dong <dong.menglong@zte.com.cn>

The initialization for 'err' with '-EINVAL' is redundant and
can be removed, as it is updated soon and not used.

Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
---
 net/ipv4/udp_diag.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/udp_diag.c b/net/ipv4/udp_diag.c
index 1dbece3..b2cee9a 100644
--- a/net/ipv4/udp_diag.c
+++ b/net/ipv4/udp_diag.c
@@ -30,7 +30,7 @@ static int udp_dump_one(struct udp_table *tbl,
 			const struct inet_diag_req_v2 *req)
 {
 	struct sk_buff *in_skb = cb->skb;
-	int err = -EINVAL;
+	int err;
 	struct sock *sk = NULL;
 	struct sk_buff *rep;
 	struct net *net = sock_net(in_skb->sk);
-- 
2.7.4

Re: [PATCH] net: udp: remove redundant initialization in udp_dump_one

[Jakub Kicinski]

On Fri,  6 Nov 2020 01:42:38 -0500 menglong8.dong@gmail.com wrote:
> From: Menglong Dong <dong.menglong@zte.com.cn>
> 
> The initialization for 'err' with '-EINVAL' is redundant and
> can be removed, as it is updated soon and not used.
> 
> Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>

Applied, thanks.

[PATCH] net: udp: remove redundant initialization in udp_gro_complete

[menglong8.dong]

From: Menglong Dong <dong.menglong@zte.com.cn>

The initialization for 'err' with '-ENOSYS' is redundant and
can be removed, as it is updated soon and not used.

Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
---
 net/ipv4/udp_offload.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index b8b1fde..65860f8 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -554,7 +554,7 @@ int udp_gro_complete(struct sk_buff *skb, int nhoff,
 {
 	__be16 newlen = htons(skb->len - nhoff);
 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
-	int err = -ENOSYS;
+	int err;
 	struct sock *sk;
 
 	uh->len = newlen;
-- 
2.7.4

Re: [PATCH] net: udp: remove redundant initialization in udp_gro_complete

[Jakub Kicinski]

On Fri,  6 Nov 2020 01:42:39 -0500 menglong8.dong@gmail.com wrote:
>  {
>  	__be16 newlen = htons(skb->len - nhoff);
>  	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
> -	int err = -ENOSYS;
> +	int err;
>  	struct sock *sk;

You can also move the err declaration below struct sock *sk; to get
this closer to revert xmas tree order. In other patches it'd increase
change / potential conflict radius but here the correct position is
close enough so we can move.

[PATCH] net: udp: remove redundant initialization in udp_send_skb

[menglong8.dong]

From: Menglong Dong <dong.menglong@zte.com.cn>

The initialization for 'err' with 0 is redundant and can be removed,
as it is updated by ip_send_skb and not used before that.

Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
---
 net/ipv4/udp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ca04a8a..6953688 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -874,7 +874,7 @@ static int udp_send_skb(struct sk_buff *skb, struct flowi4 *fl4,
 	struct sock *sk = skb->sk;
 	struct inet_sock *inet = inet_sk(sk);
 	struct udphdr *uh;
-	int err = 0;
+	int err;
 	int is_udplite = IS_UDPLITE(sk);
 	int offset = skb_transport_offset(skb);
 	int len = skb->len - offset;
-- 
2.7.4

Re: [PATCH] net: udp: remove redundant initialization in udp_send_skb

[Jakub Kicinski]

On Fri,  6 Nov 2020 01:42:40 -0500 menglong8.dong@gmail.com wrote:
> From: Menglong Dong <dong.menglong@zte.com.cn>
> 
> The initialization for 'err' with 0 is redundant and can be removed,
> as it is updated by ip_send_skb and not used before that.
> 
> Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>

Applied.

Re: [PATCH] net: ipv4: remove redundant initialization in inet_rtm_deladdr

[Jakub Kicinski]

On Fri,  6 Nov 2020 01:42:37 -0500 menglong8.dong@gmail.com wrote:
> From: Menglong Dong <dong.menglong@zte.com.cn>
> 
> The initialization for 'err' with '-EINVAL' is redundant and
> can be removed, as it is updated soon.
> 
> Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>

How many changes like this are there in the kernel right now?

I'm afraid that if there are too many it's not worth the effort.

Also - what tool do you use to find those, we need to make sure new
instances don't get into the tree.

> diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
> index 123a6d3..847cb18 100644
> --- a/net/ipv4/devinet.c
> +++ b/net/ipv4/devinet.c
> @@ -651,7 +651,7 @@ static int inet_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh,
>  	struct ifaddrmsg *ifm;
>  	struct in_ifaddr *ifa;
>  

You can remove this empty line while at it.

> -	int err = -EINVAL;
> +	int err;
>  
>  	ASSERT_RTNL();
>  

Re: [PATCH] net: ipv4: remove redundant initialization in inet_rtm_deladdr

[Menglong Dong]

Dear Jakub,

On Sun, Nov 8, 2020 at 7:48 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Fri,  6 Nov 2020 01:42:37 -0500 menglong8.dong@gmail.com wrote:
> > From: Menglong Dong <dong.menglong@zte.com.cn>
> >
> > The initialization for 'err' with '-EINVAL' is redundant and
> > can be removed, as it is updated soon.
> >
> > Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
>
> How many changes like this are there in the kernel right now?
>
> I'm afraid that if there are too many it's not worth the effort.
>
> Also - what tool do you use to find those, we need to make sure new
> instances don't get into the tree.
>

I didn't use any tools. Maybe some general tools, such as kw,
coverity, coccicheck,
are able to find these changes(as far as I know, they can).

In fact, I find these changes by my eyes. I believe 'err' is the most
likely victim
and checked every usage of it in 'net' directory. Here are all the
changes I found,
and I think there won't be too many.

Cheers,
Menglong Dong