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SubjectRe: [PATCH net-next v2 4/4] bonding: balance ICMP echoes in layer3+4 mode
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On 30/10/2019 01:04, Eric Dumazet wrote:
>
>
> On 10/29/19 2:50 PM, Nikolay Aleksandrov wrote:
>
>> Right, I was just giving it as an example. Your suggestion sounds much better and
>> wouldn't interfere with other layers, plus we already use skb->hash in bond_xmit_hash()
>> and skb_set_owner_w() sets l4_hash if txhash is present which is perfect.
>>
>> One thing - how do we deal with sk_rethink_txhash() ? I guess we'll need some way to
>> signal that the user specified the txhash and it is not to be recomputed ?
>> That can also be used to avoid the connect txhash set as well if SO_TXHASH was set prior
>> to the connect. It's quite late here, I'll look into it more tomorrow. :)
>
> I guess that we have something similar with SO_RCVBUF/SO_SNDBUF
>
> autotuning is disabled when/if they are used :
>
> SOCK_RCVBUF_LOCK & SOCK_SNDBUF_LOCK
>
> We could add a SOCK_TXHASH_LOCK so that sk_rethink_txhash() does nothing if
> user forced a TXHASH value.
>
> Something like the following (probably not complete) patch.
>

Actually I think it's ok. I had a similar change last night sans the userlocks.
I just built and tested a kernel with it successfully using the bonding.
The only case that doesn't seem to work is a raw socket without hdrincl, IIUC due to
the direct alloc_skb() (transhdrlen == 0) in ip_append_data().
Unless you have other concerns could you please submit it formally ?

> diff --git a/include/net/sock.h b/include/net/sock.h
> index 380312cc67a9d9ee8720eb2db82b1f7f8a5615ab..a8882738710eaa9d9d629e1207837a798401a594 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -1354,6 +1354,7 @@ static inline int __sk_prot_rehash(struct sock *sk)
> #define SOCK_RCVBUF_LOCK 2
> #define SOCK_BINDADDR_LOCK 4
> #define SOCK_BINDPORT_LOCK 8
> +#define SOCK_TXHASH_LOCK 16
>
> struct socket_alloc {
> struct socket socket;
> @@ -1852,7 +1853,8 @@ static inline u32 net_tx_rndhash(void)
>
> static inline void sk_set_txhash(struct sock *sk)
> {
> - sk->sk_txhash = net_tx_rndhash();
> + if (!(sk->sk_userlocks & SOCK_TXHASH_LOCK))
> + sk->sk_txhash = net_tx_rndhash();
> }
>
> static inline void sk_rethink_txhash(struct sock *sk)
> diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
> index 77f7c1638eb1ce7d3e143bbffd60056e472b1122..998be6ee7991de3a76d4ad33df3a38dbe791eae8 100644
> --- a/include/uapi/asm-generic/socket.h
> +++ b/include/uapi/asm-generic/socket.h
> @@ -118,6 +118,7 @@
> #define SO_SNDTIMEO_NEW 67
>
> #define SO_DETACH_REUSEPORT_BPF 68
> +#define SO_TXHASH 69
>
> #if !defined(__KERNEL__)
>
> diff --git a/net/core/sock.c b/net/core/sock.c
> index 997b352c2a72ee39f00b102a553ac1191202b74f..85b85dffd462bc3b497e0432100ff24b759832e0 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -770,6 +770,10 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
> case SO_BROADCAST:
> sock_valbool_flag(sk, SOCK_BROADCAST, valbool);
> break;
> + case SO_TXHASH:
> + sk->sk_txhash = val;
> + sk->sk_userlocks |= SOCK_TXHASH_LOCK;
> + break;
> case SO_SNDBUF:
> /* Don't error on this BSD doesn't and if you think
> * about it this is right. Otherwise apps have to
> @@ -1249,6 +1253,10 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
> v.val = sock_flag(sk, SOCK_BROADCAST);
> break;
>
> + case SO_TXHASH:
> + v.val = sk->sk_txhash;
> + break;
> +
> case SO_SNDBUF:
> v.val = sk->sk_sndbuf;
> break;
>

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