Re: [PATCH v3 1/2] io_uring/zcrx: add a read limit to recvzc requests

[Pavel Begunkov <asml.silence@gmail.com>]

On 2/24/25 04:13, David Wei wrote:
> Currently multishot recvzc requests have no read limit and will remain
> active so as long as the socket remains open. But, there are sometimes a
> need to do a fixed length read e.g. peeking at some data in the socket.
> 
> Add a length limit to recvzc requests `len`. A value of 0 means no limit
> which is the previous behaviour. A positive value N specifies how many
> bytes to read from the socket.
> 
> Data will still be posted in aux completions, as before. This could be
> split across multiple frags. But the primary recvzc request will now
> complete once N bytes have been read. The completion of the recvzc
> request will have res and cflags both set to 0.

Looks fine, can be improved later.

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>


> Signed-off-by: David Wei <dw@davidwei.uk>
> ---
>   io_uring/net.c  | 16 +++++++++++++---
>   io_uring/zcrx.c | 13 +++++++++----
>   io_uring/zcrx.h |  2 +-
>   3 files changed, 23 insertions(+), 8 deletions(-)
...
> diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
> index f2d326e18e67..9c95b5b6ec4e 100644
> --- a/io_uring/zcrx.c
> +++ b/io_uring/zcrx.c
> @@ -817,6 +817,7 @@ io_zcrx_recv_skb(read_descriptor_t *desc, struct sk_buff *skb,
...
>   static int io_zcrx_tcp_recvmsg(struct io_kiocb *req, struct io_zcrx_ifq *ifq,
>   				struct sock *sk, int flags,
> -				unsigned issue_flags)
> +				unsigned issue_flags, unsigned int *outlen)
>   {
> +	unsigned int len = *outlen;
>   	struct io_zcrx_args args = {
>   		.req = req,
>   		.ifq = ifq,
>   		.sock = sk->sk_socket,
>   	};
>   	read_descriptor_t rd_desc = {
> -		.count = 1,
> +		.count = len ? len : UINT_MAX,

typedef struct {
	...
	size_t count;
} read_descriptor_t;

Should be SIZE_MAX, but it's not worth of respinning.

-- 
Pavel Begunkov