On 4/11/23 8:51?AM, Willem de Bruijn wrote: > Jens Axboe wrote: >> On 4/11/23 8:36?AM, David Ahern wrote: >>> On 4/11/23 6:00 AM, Breno Leitao wrote: >>>> I am not sure if avoiding io_uring details in network code is possible. >>>> >>>> The "struct proto"->uring_cmd callback implementation (tcp_uring_cmd() >>>> in the TCP case) could be somewhere else, such as in the io_uring/ >>>> directory, but, I think it might be cleaner if these implementations are >>>> closer to function assignment (in the network subsystem). >>>> >>>> And this function (tcp_uring_cmd() for instance) is the one that I am >>>> planning to map io_uring CMDs to ioctls. Such as SOCKET_URING_OP_SIOCINQ >>>> -> SIOCINQ. >>>> >>>> Please let me know if you have any other idea in mind. >>> >>> I am not convinced that this io_uring_cmd is needed. This is one >>> in-kernel subsystem calling into another, and there are APIs for that. >>> All of this set is ioctl based and as Willem noted a little refactoring >>> separates the get_user/put_user out so that in-kernel can call can be >>> made with existing ops. >> >> How do you want to wire it up then? We can't use fops->unlocked_ioctl() >> obviously, and we already have ->uring_cmd() for this purpose. > > Does this suggestion not work? Not sure I follow, what suggestion? >>> I was thinking just having sock_uring_cmd call sock->ops->ioctl, like >>> sock_do_ioctl. > >> I do think the right thing to do is have a common helper that returns >> whatever value you want (or sets it), and split the ioctl parts into a >> wrapper around that that simply copies in/out as needed. Then >> ->uring_cmd() could call that, or you could some exported function that >> does supports that. >> >> This works for the basic cases, though I do suspect we'll want to go >> down the ->uring_cmd() at some point for more advanced cases or cases >> that cannot sanely be done in an ioctl fashion. > > Right now the two examples are ioctls that return an integer. Do you > already have other calls in mind? That would help estimate whether > ->uring_cmd() indeed will be needed and we might as well do it now. Right, it's a proof of concept. But we'd want to support anything that setsockopt/getsockopt would do. This is necessary so that direct descriptors (eg ones that describe a struct file that isn't in the process file table or have a regular fd) can be used for anything that a regular file can. Beyond that, perhaps various things necessary for efficient zero copy rx. I do think we can make the ->uring_cmd() hookup a bit more palatable in terms of API. It really should be just a sub-opcode and then arguments to support that. The grunt of the work is really refactoring the ioctl and set/getsockopt bits so that they can be called in-kernel rather than assuming copy in/out is needed. Once that is done, the actual uring_cmd hookup should be simple and trivial. -- Jens Axboe
