diff mbox series

[net-next,v3,2/3] net: icmp: introduce __ping_queue_rcv_skb() to report drop reasons

Message ID 20220316063148.700769-3-imagedong@tencent.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: icmp: add skb drop reasons to icmp | expand

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netdev/header_inline success No static functions without inline keyword in header files
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netdev/verify_fixes success No Fixes tag
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netdev/source_inline success Was 0 now: 0

Commit Message

Menglong Dong March 16, 2022, 6:31 a.m. UTC 
From: Menglong Dong <imagedong@tencent.com>

In order to avoid to change the return value of ping_queue_rcv_skb(),
introduce the function __ping_queue_rcv_skb(), which is able to report
the reasons of skb drop as its return value, as Paolo suggested.

Meanwhile, make ping_queue_rcv_skb() a simple call to
__ping_queue_rcv_skb().

The kfree_skb() and sock_queue_rcv_skb() used in ping_queue_rcv_skb()
are replaced with kfree_skb_reason() and sock_queue_rcv_skb_reason()
now.

Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
v3:
- fix aligenment problem

v2:
- introduce __ping_queue_rcv_skb() instead of change the return value
  of ping_queue_rcv_skb()
---
 net/ipv4/ping.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

Comments

David Ahern March 17, 2022, 3:56 a.m. UTC | #1 
On 3/16/22 12:31 AM, menglong8.dong@gmail.com wrote:
> diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> index 3ee947557b88..9a1ea6c263f8 100644
> --- a/net/ipv4/ping.c
> +++ b/net/ipv4/ping.c
> @@ -934,16 +934,24 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
>  }
>  EXPORT_SYMBOL_GPL(ping_recvmsg);
>  
> -int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> +static enum skb_drop_reason __ping_queue_rcv_skb(struct sock *sk,
> +						 struct sk_buff *skb)
>  {
> +	enum skb_drop_reason reason;
> +
>  	pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)\n",
>  		 inet_sk(sk), inet_sk(sk)->inet_num, skb);
> -	if (sock_queue_rcv_skb(sk, skb) < 0) {
> -		kfree_skb(skb);
> +	if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0) {
> +		kfree_skb_reason(skb, reason);
>  		pr_debug("ping_queue_rcv_skb -> failed\n");
> -		return -1;
> +		return reason;
>  	}
> -	return 0;
> +	return SKB_NOT_DROPPED_YET;
> +}
> +
> +int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> +{
> +	return __ping_queue_rcv_skb(sk, skb) ?: -1;
>  }
>  EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);
>  

This is a generic proto callback and you are now changing its return
code in a way that seems to conflict with existing semantics
Menglong Dong March 17, 2022, 5:25 a.m. UTC | #2 
On Thu, Mar 17, 2022 at 11:56 AM David Ahern <dsahern@kernel.org> wrote:
>
> On 3/16/22 12:31 AM, menglong8.dong@gmail.com wrote:
> > diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> > index 3ee947557b88..9a1ea6c263f8 100644
> > --- a/net/ipv4/ping.c
> > +++ b/net/ipv4/ping.c
> > @@ -934,16 +934,24 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
> >  }
> >  EXPORT_SYMBOL_GPL(ping_recvmsg);
> >
> > -int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> > +static enum skb_drop_reason __ping_queue_rcv_skb(struct sock *sk,
> > +                                              struct sk_buff *skb)
> >  {
> > +     enum skb_drop_reason reason;
> > +
> >       pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)\n",
> >                inet_sk(sk), inet_sk(sk)->inet_num, skb);
> > -     if (sock_queue_rcv_skb(sk, skb) < 0) {
> > -             kfree_skb(skb);
> > +     if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0) {
> > +             kfree_skb_reason(skb, reason);
> >               pr_debug("ping_queue_rcv_skb -> failed\n");
> > -             return -1;
> > +             return reason;
> >       }
> > -     return 0;
> > +     return SKB_NOT_DROPPED_YET;
> > +}
> > +
> > +int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> > +{
> > +     return __ping_queue_rcv_skb(sk, skb) ?: -1;
> >  }
> >  EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);
> >
>
> This is a generic proto callback and you are now changing its return
> code in a way that seems to conflict with existing semantics

The return value of ping_queue_rcv_skb() seems not changed.
In the previous code, -1 is returned on failure and 0 for success.
This logic isn't changed, giving __ping_queue_rcv_skb() != 0 means
failure and -1 is returned. Isn't it?
Paolo Abeni March 17, 2022, 8:33 a.m. UTC | #3 
On Thu, 2022-03-17 at 13:25 +0800, Menglong Dong wrote:
> On Thu, Mar 17, 2022 at 11:56 AM David Ahern <dsahern@kernel.org> wrote:
> > 
> > On 3/16/22 12:31 AM, menglong8.dong@gmail.com wrote:
> > > diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> > > index 3ee947557b88..9a1ea6c263f8 100644
> > > --- a/net/ipv4/ping.c
> > > +++ b/net/ipv4/ping.c
> > > @@ -934,16 +934,24 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
> > >  }
> > >  EXPORT_SYMBOL_GPL(ping_recvmsg);
> > > 
> > > -int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> > > +static enum skb_drop_reason __ping_queue_rcv_skb(struct sock *sk,
> > > +                                              struct sk_buff *skb)
> > >  {
> > > +     enum skb_drop_reason reason;
> > > +
> > >       pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)\n",
> > >                inet_sk(sk), inet_sk(sk)->inet_num, skb);
> > > -     if (sock_queue_rcv_skb(sk, skb) < 0) {
> > > -             kfree_skb(skb);
> > > +     if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0) {
> > > +             kfree_skb_reason(skb, reason);
> > >               pr_debug("ping_queue_rcv_skb -> failed\n");
> > > -             return -1;
> > > +             return reason;
> > >       }
> > > -     return 0;
> > > +     return SKB_NOT_DROPPED_YET;
> > > +}
> > > +
> > > +int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> > > +{
> > > +     return __ping_queue_rcv_skb(sk, skb) ?: -1;
> > >  }
> > >  EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);
> > > 
> > 
> > This is a generic proto callback and you are now changing its return
> > code in a way that seems to conflict with existing semantics
> 
> The return value of ping_queue_rcv_skb() seems not changed.
> In the previous code, -1 is returned on failure and 0 for success.
> This logic isn't changed, giving __ping_queue_rcv_skb() != 0 means
> failure and -1 is returned. Isn't it?

With this patch, on failure __ping_queue_rcv_skb() returns 'reason' (>
0) and ping_queue_rcv_skb() returns the same value.

On success __ping_queue_rcv_skb() returns SKB_NOT_DROPPED_YET (==0) and
ping_queue_rcv_skb() return -1.

You need to preserve the old ping_queue_rcv_skb() return values, under
the same circumstances.

Thanks,

Paolo
Menglong Dong March 17, 2022, 8:36 a.m. UTC | #4 
On Thu, Mar 17, 2022 at 4:33 PM Paolo Abeni <pabeni@redhat.com> wrote:
>
> On Thu, 2022-03-17 at 13:25 +0800, Menglong Dong wrote:
> > On Thu, Mar 17, 2022 at 11:56 AM David Ahern <dsahern@kernel.org> wrote:
> > >
> > > On 3/16/22 12:31 AM, menglong8.dong@gmail.com wrote:
> > > > diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
> > > > index 3ee947557b88..9a1ea6c263f8 100644
> > > > --- a/net/ipv4/ping.c
> > > > +++ b/net/ipv4/ping.c
> > > > @@ -934,16 +934,24 @@ int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(ping_recvmsg);
> > > >
> > > > -int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> > > > +static enum skb_drop_reason __ping_queue_rcv_skb(struct sock *sk,
> > > > +                                              struct sk_buff *skb)
> > > >  {
> > > > +     enum skb_drop_reason reason;
> > > > +
> > > >       pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)\n",
> > > >                inet_sk(sk), inet_sk(sk)->inet_num, skb);
> > > > -     if (sock_queue_rcv_skb(sk, skb) < 0) {
> > > > -             kfree_skb(skb);
> > > > +     if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0) {
> > > > +             kfree_skb_reason(skb, reason);
> > > >               pr_debug("ping_queue_rcv_skb -> failed\n");
> > > > -             return -1;
> > > > +             return reason;
> > > >       }
> > > > -     return 0;
> > > > +     return SKB_NOT_DROPPED_YET;
> > > > +}
> > > > +
> > > > +int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
> > > > +{
> > > > +     return __ping_queue_rcv_skb(sk, skb) ?: -1;
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);
> > > >
> > >
> > > This is a generic proto callback and you are now changing its return
> > > code in a way that seems to conflict with existing semantics
> >
> > The return value of ping_queue_rcv_skb() seems not changed.
> > In the previous code, -1 is returned on failure and 0 for success.
> > This logic isn't changed, giving __ping_queue_rcv_skb() != 0 means
> > failure and -1 is returned. Isn't it?
>
> With this patch, on failure __ping_queue_rcv_skb() returns 'reason' (>
> 0) and ping_queue_rcv_skb() returns the same value.
>
> On success __ping_queue_rcv_skb() returns SKB_NOT_DROPPED_YET (==0) and
> ping_queue_rcv_skb() return -1.
>
> You need to preserve the old ping_queue_rcv_skb() return values, under
> the same circumstances.

Oops...my mistake....:)

Thanks for your explanation!

Menglong Dong

>
> Thanks,
>
> Paolo
>
diff mbox series

Patch

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 3ee947557b88..9a1ea6c263f8 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -934,16 +934,24 @@  int ping_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
 }
 EXPORT_SYMBOL_GPL(ping_recvmsg);
 
-int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+static enum skb_drop_reason __ping_queue_rcv_skb(struct sock *sk,
+						 struct sk_buff *skb)
 {
+	enum skb_drop_reason reason;
+
 	pr_debug("ping_queue_rcv_skb(sk=%p,sk->num=%d,skb=%p)\n",
 		 inet_sk(sk), inet_sk(sk)->inet_num, skb);
-	if (sock_queue_rcv_skb(sk, skb) < 0) {
-		kfree_skb(skb);
+	if (sock_queue_rcv_skb_reason(sk, skb, &reason) < 0) {
+		kfree_skb_reason(skb, reason);
 		pr_debug("ping_queue_rcv_skb -> failed\n");
-		return -1;
+		return reason;
 	}
-	return 0;
+	return SKB_NOT_DROPPED_YET;
+}
+
+int ping_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	return __ping_queue_rcv_skb(sk, skb) ?: -1;
 }
 EXPORT_SYMBOL_GPL(ping_queue_rcv_skb);