On Mon, Dec 20, 2021 at 07:47:22PM +0530, Kanchan Joshi wrote:
> Completion of a uring_cmd ioctl may involve referencing certain
> ioctl-specific fields, requiring original submitter context.
> Export an API that driver can use for this purpose.
> The API facilitates reusing task-work infra of io_uring, while driver
> gets to implement cmd-specific handling in a callback.
>
> Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
> Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
> ---
> fs/io_uring.c | 16 ++++++++++++++++
> include/linux/io_uring.h | 8 ++++++++
> 2 files changed, 24 insertions(+)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index e96ed3d0385e..246f1085404d 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2450,6 +2450,22 @@ static void io_req_task_submit(struct io_kiocb *req, bool *locked)
> io_req_complete_failed(req, -EFAULT);
> }
>
> +static void io_uring_cmd_work(struct io_kiocb *req, bool *locked)
> +{
> + req->uring_cmd.driver_cb(&req->uring_cmd);
If the callback memory area is gone, boom.
> +}
> +
> +void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
> + void (*driver_cb)(struct io_uring_cmd *))
Adding kdoc style comment for this would be nice. Please document
the context that is allowed.
> +{
> + struct io_kiocb *req = container_of(ioucmd, struct io_kiocb, uring_cmd);
> +
> + req->uring_cmd.driver_cb = driver_cb;
> + req->io_task_work.func = io_uring_cmd_work;
> + io_req_task_work_add(req, !!(req->ctx->flags & IORING_SETUP_SQPOLL));
This can schedules, and so the callback may go fishing in the meantime.
> +}
> +EXPORT_SYMBOL_GPL(io_uring_cmd_complete_in_task);
> +
> static void io_req_task_queue_fail(struct io_kiocb *req, int ret)
> {
> req->result = ret;
> diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
> index 64e788b39a86..f4b4990a3b62 100644
> --- a/include/linux/io_uring.h
> +++ b/include/linux/io_uring.h
> @@ -14,11 +14,15 @@ struct io_uring_cmd {
> __u16 op;
> __u16 unused;
> __u32 len;
> + /* used if driver requires update in task context*/
By using kdoc above youcan remove this comment.
> + void (*driver_cb)(struct io_uring_cmd *cmd);
So we'd need a struct module here I think if we're going to
defer this into memory which can be removed.
Luis
