On 12/01/2021 21:33, Bijan Mottahedeh wrote:
> Implement buffer sharing among multiple rings.
>
> A ring shares its (future) buffer registrations at setup time with
> IORING_SETUP_SHARE_BUF. A ring attaches to another ring's buffer
> registration at setup time with IORING_SETUP_ATTACH_BUF, after
> authenticating with the buffer registration owner's fd. Any updates to
> the owner's buffer registrations become immediately available to the
> attached rings.
I'm thinking it through, but there is an easy to miss potential bug,
so see below a comment to not forget.
>
> Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@xxxxxxxxxx>
>
> Conflicts:
> fs/io_uring.c
> ---
> fs/io_uring.c | 85 +++++++++++++++++++++++++++++++++++++++++--
> include/uapi/linux/io_uring.h | 2 +
> 2 files changed, 83 insertions(+), 4 deletions(-)
[...]
> +
> +static int io_init_buf_data(struct io_ring_ctx *ctx, struct io_uring_params *p)
> +{
> + if ((p->flags & (IORING_SETUP_SHARE_BUF | IORING_SETUP_ATTACH_BUF)) ==
> + (IORING_SETUP_SHARE_BUF | IORING_SETUP_ATTACH_BUF))
> + return -EINVAL;
> +
> + if (p->flags & IORING_SETUP_SHARE_BUF) {
> + struct fixed_rsrc_data *buf_data;
> +
> + buf_data = alloc_fixed_rsrc_data(ctx);
> + if (IS_ERR(buf_data))
> + return PTR_ERR(buf_data);
Because of sneaked through 5.11 fixes it'll be
if (!buf_data) return -ENOMEM
> +
> + ctx->buf_data = buf_data;
> + return 0;
> + }
> +
> + if (p->flags & IORING_SETUP_ATTACH_BUF)
> + return io_attach_buf_data(ctx, p);
> +
> + return 0;
> +}
> +
--
Pavel Begunkov
