Re: [PATCH 1/1] io_uring/net: send retry for zerocopy

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

On 8/14/22 15:48, Stefan Metzmacher wrote:
> Am 14.08.22 um 16:13 schrieb Jens Axboe:
>> On 8/14/22 8:11 AM, Stefan Metzmacher wrote:
>>>>> Don't we need a prep_async function and/or something like
>>>>> io_setup_async_msg() here to handle address?

>>> This has support for sockaddr address compared to io_send(),
>>> if the caller need to keep io_sendzc->addr valid until the qce arrived,
>>> then we need to clearly document that, as that doesn't match the common practice
>>> of other opcodes. Currently everything but data buffers can go after the sqe is
>>> submitted.

Yes, can be this way if we agree it's preferable.

>> Good point, it's not just the 'from' address. Pavel?

It is

> It's basically dest_addr from:
> 
>         ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
>                        const struct sockaddr *dest_addr, socklen_t addrlen);
> 
> It's not used in most cases, but for non-connected udp sockets you need it.
> 
> Maybe the fixed io_op_def.async_size could be changed to something that only
> allocated the async data if needed. Maybe the prep_async() hook could to the allocation
> itself if needed.

It's details, easy to implement, e.g. we can just decouple the
allocation from async preparation. I'll give it a try after sending
other small zc API changes

-- 
Pavel Begunkov