On 6/13/22 22:05, Pavel Begunkov wrote:
On 6/13/22 14:16, Dylan Yudaken wrote:
On Mon, 2022-06-13 at 13:59 +0100, Pavel Begunkov wrote:
On 6/13/22 12:08, Hao Xu wrote:
On 6/13/22 18:11, Dylan Yudaken wrote:
This fixes two problems in the new provided buffer ring feature.
One
is a simple arithmetic bug (I think this came out from a
refactor).
The other is due to type differences between head & tail, which
causes
it to sometimes reuse an old buffer incorrectly.
Patch 1&2 fix bugs
Patch 3 limits the size of the ring as it's not
possible to address more entries with 16 bit head/tail
Reviewed-by: Hao Xu <howeyxu@xxxxxxxxxxx>
I will send test cases for liburing shortly.
One question might be if we should change the type of
ring_entries
to uint16_t in struct io_uring_buf_reg?
Why not? 5.19 is just rc2 now. So we can assume there is no users
using
it right now I think?
It's fine to change, but might be better if we want to extend it
in the future. Do other pbuf bits allow more than 2^16 buffers?
might be better to leave it u32 *
I guess with
+ if (reg.ring_entries >= 65536)
+ return -EINVAL;
it doesn't matter either way. we can always use those bits later if we
need?
I think so as well.
I was also wondering whether pbufs can potentially allow >16 bits,
but taking a quick look IORING_CQE_BUFFER_SHIFT=16, so we only have
16 bits in cqe::flags for indexes we return.
Yea, the 16 bits return index in cqe->flags is a hard limit for
pbuf ring feature, but I do think it's ok since 1<<16 is already big
