Match up work done in "io_uring: allow iov_len = 0 for recvmsg and buffer
select", but for compat code path.
Fixes: a68caad69ce5 ("io_uring: allow iov_len = 0 for recvmsg and buffer select")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220708181838.1495428-3-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If multishot is not actually polling then return IOU_OK rather than the
result.
If the result was > 0 this will confuse things further up the callstack
which expect a return <= 0.
Fixes: 1300ebb20286 ("io_uring: multishot recv")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220708181838.1495428-2-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
For recvmsg/sendmsg, if they don't complete inline, we currently need
to allocate a struct io_async_msghdr for each request. This is a
somewhat large struct.
Hook up sendmsg/recvmsg to use the io_alloc_cache. This reduces the
alloc + free overhead considerably, yielding 4-5% of extra performance
running netbench.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
recvmsg has semantics that do not make it trivial to extend to
multishot. Specifically it has user pointers and returns data in the
original parameter. In order to make this API useful these will need to be
somehow included with the provided buffers.
For now remove multishot for recvmsg as it is not useful.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220704140106.200167-1-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Support multishot receive for io_uring.
Typical server applications will run a loop where for each recv CQE it
requeues another recv/recvmsg.
This can be simplified by using the existing multishot functionality
combined with io_uring's provided buffers.
The API is to add the IORING_RECV_MULTISHOT flag to the SQE. CQEs will
then be posted (with IORING_CQE_F_MORE flag set) when data is available
and is read. Once an error occurs or the socket ends, the multishot will
be removed and a completion without IORING_CQE_F_MORE will be posted.
The benefit to this is that the recv is much more performant.
* Subsequent receives are queued up straight away without requiring the
application to finish a processing loop.
* If there are more data in the socket (sat the provided buffer size is
smaller than the socket buffer) then the data is immediately
returned, improving batching.
* Poll is only armed once and reused, saving CPU cycles
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-11-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Some use cases of io_post_aux_cqe would not want to overflow as is, but
might want to change the flags/result. For example multishot receive
requires in order CQE, and so if there is an overflow it would need to
stop receiving until the overflow is taken care of.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-8-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Rather than passing an error back to the user with a buffer attached,
recycle the buffer immediately.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-5-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When using BUFFER_SELECT there is no technical requirement that the user
actually provides iov, and this removes one copy_from_user call.
So allow iov_len to be 0.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220630091231.1456789-4-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
