On 10/20/22 2:13 AM, Stefan Metzmacher wrote:
> Hi Pavel,
>
>> If a protocol doesn't support zerocopy it will silently fall back to
>> copying. This type of behaviour has always been a source of troubles
>> so it's better to fail such requests instead. For now explicitly
>> whitelist supported protocols in io_uring, which should be turned later
>> into a socket flag.
>>
>> Cc: <stable@xxxxxxxxxxxxxxx> # 6.0
>> Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
>> ---
>> io_uring/net.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> diff --git a/io_uring/net.c b/io_uring/net.c
>> index 8c7226b5bf41..28127f1de1f0 100644
>> --- a/io_uring/net.c
>> +++ b/io_uring/net.c
>> @@ -120,6 +120,13 @@ static void io_netmsg_recycle(struct io_kiocb *req, unsigned int issue_flags)
>> }
>> }
>> +static inline bool io_sock_support_zc(struct socket *sock)
>> +{
>> + return likely(sock->sk && sk_fullsock(sock->sk) &&
>> + (sock->sk->sk_protocol == IPPROTO_TCP ||
>> + sock->sk->sk_protocol == IPPROTO_UDP));
>> +}
>
> Can we please make this more generic (at least for 6.1, which is likely be an lts release)
>
> It means my out of tree smbdirect driver would not be able to provide SENDMSG_ZC.
>
> Currently sk_setsockopt has this logic:
>
> case SO_ZEROCOPY:
> if (sk->sk_family == PF_INET || sk->sk_family == PF_INET6) {
> if (!(sk_is_tcp(sk) ||
> (sk->sk_type == SOCK_DGRAM &&
> sk->sk_protocol == IPPROTO_UDP)))
> ret = -EOPNOTSUPP;
> } else if (sk->sk_family != PF_RDS) {
> ret = -EOPNOTSUPP;
> }
> if (!ret) {
> if (val < 0 || val > 1)
> ret = -EINVAL;
> else
> sock_valbool_flag(sk, SOCK_ZEROCOPY, valbool);
> }
> break;
>
> Maybe the socket creation code could set
> unsigned char skc_so_zerocopy_supported:1;
> and/or
> unsigned char skc_zerocopy_msg_ubuf_supported:1;
>
> In order to avoid the manual complex tests.
I agree that would be cleaner, even for 6.1. Let's drop these two
for now.
--
Jens Axboe
