2022-03-16 15:56:56

by Menglong Dong

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

From: Menglong Dong <[email protected]>

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 <[email protected]>
Reviewed-by: Jiang Biao <[email protected]>
Signed-off-by: Menglong Dong <[email protected]>
---
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(-)

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);

--
2.35.1

2022-03-17 05:53:43

by Menglong Dong

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

On Thu, Mar 17, 2022 at 11:56 AM David Ahern <[email protected]> wrote:
>
> On 3/16/22 12:31 AM, [email protected] 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?

2022-03-17 06:18:12

by David Ahern

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

On 3/16/22 12:31 AM, [email protected] 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

2022-03-17 09:24:41

by Menglong Dong

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

On Thu, Mar 17, 2022 at 4:33 PM Paolo Abeni <[email protected]> wrote:
>
> On Thu, 2022-03-17 at 13:25 +0800, Menglong Dong wrote:
> > On Thu, Mar 17, 2022 at 11:56 AM David Ahern <[email protected]> wrote:
> > >
> > > On 3/16/22 12:31 AM, [email protected] 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
>

2022-03-17 10:14:17

by Paolo Abeni

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

On Thu, 2022-03-17 at 13:25 +0800, Menglong Dong wrote:
> On Thu, Mar 17, 2022 at 11:56 AM David Ahern <[email protected]> wrote:
> >
> > On 3/16/22 12:31 AM, [email protected] 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