When will IORING_CQE_F_MORE not be set while using multishot-accept?

[chimaoshu]

In io_uring_prep_recv_multishot, IORING_CQE_F_MORE will not be set in CQE flags when sever has read out of all data from a client send().(edit: that's not true) How about the io_uring_prep_multishot_accept? Under what circumstance will the listen_fd not "generate further CQEs"?

For example, if a client has connect() to the server, and multishot-accept successfully accepts it and generates a CQE, and there is no other client trying to connect() to the server at this time, will IORING_CQE_F_MORE be set?

According to Linux kernel, it seems that multishot-accept will always set IORING_CQE_F_MORE in CQE once the accept operation is successfully done, am I right?

[axboe]

It will remain set until an error has occurred accepting a connection. accept doesn't know if nobody else is trying to connect yet, that's a situation that could change at any point in time. Like any multishot request, it'll remain active until ones of these are true:

1. An error happens while accepting a connection
2. It's actively canceled by the application

[redbaron]

In io_uring_prep_recv_multishot, IORING_CQE_F_MORE will not be set in CQE flags when sever has read out of all data from a client send()

Is it true? I thought recv remains active as long as connection stays up

[axboe]

No it's not true, where is that from? It'll stay active with the same rules as mentioned in #822 (comment)

[axboe]

If it were true, there would be no difference between a normal recv and a multishot recv at that point. If all the data has been received, poll will be armed again and trigger when more data is available in the socket. Repeat until one of the termination conditions are met.

[chimaoshu]

No it's not true, where is that from? It'll stay active with the same rules as mentioned in #822 (comment)

So a single io_uring_prep_recv_multishot() can handle multiple send() from clients?
It may sound funny that I got that wrong info from Microsoft's AI new bing. I asked it about multishot-recv and it told me that multishot-recv is used in a single recv with large data size, also told me that IORING_CQE_F_MORE will not be set if server has read out of all data from a client send().

[axboe]

Of course, otherwise it'd just be a normal send. Don't trust any of the LLM generative AIs, they make shit up all the time... So yes, both of the things it told you is utter garbage.

[axboe]

For the last one, it has nothing to do with IORING_CQE_F_MORE, but IORING_CQE_F_SOCK_NONEMPTY is set in the cqe if there socket was NOT empty when the receive was done. Again this really has nothing to do with multishot, that's a generic receive property.