On 9/28/22 11:55, Ben Noordhuis wrote:
On Wed, Sep 28, 2022 at 12:02 PM Pavel Begunkov <asml.silence@xxxxxxxxx> wrote:
On 9/28/22 10:50, Ben Noordhuis wrote:
I'm trying to chain accept+read but it's not working.
My code looks like this:
*sqe1 = (struct io_uring_sqe){
.opcode = IORING_OP_ACCEPT,
.flags = IOSQE_IO_LINK,
.fd = listenfd,
.file_index = 42, // or 42+1
};
*sqe2 = (struct io_uring_sqe){
.opcode = IORING_OP_READ,
.flags = IOSQE_FIXED_FILE,
.addr = (u64) buf,
.len = len,
.fd = 42,
};
submit();
Both ops fail immediately; accept with -ECANCELED, read with -EBADF,
presumably because fixed fd 42 doesn't exist at the time of submission.
Would it be possible to support this pattern in io_uring or are there
reasons for why things are the way they are?
It should already be supported. And errors look a bit odd, I'd rather
expect -EBADF or some other for accept and -ECANCELED for the read.
Do you have a test program / reporoducer? Hopefully in C.
Of course, please see below. Error handling elided for brevity. Hope
I'm not doing anything stupid.
Perfect thanks
For me it immediately prints this:
0 res=-125
1 res=-9
The reason is that in older kernels we're resolving the read's
file not after accept but when assembling the link, which was
specifically fixed a bit later. Jens, are there any plans to
backport it?
--
Pavel Begunkov
