On 14/04/2023 07:10, Pavel Begunkov wrote:
> >
> On 4/12/23 23:27, David Wei wrote:
>> A multishot timeout submission will repeatedly generate completions with
>> the IORING_CQE_F_MORE cflag set. Depending on the value of the `off' field
>> in the submission, these timeouts can either repeat indefinitely until
>> cancelled (`off' = 0) or for a fixed number of times (`off' > 0).
>>
>> Only noseq timeouts (i.e. not dependent on the number of I/O
>> completions) are supported.
>>
>> An indefinite timer will be cancelled with EOVERFLOW if the CQ ever
>> overflows.
>
> Seems mostly fine, two comments below
>
>
>> Signed-off-by: David Wei <davidhwei@xxxxxxxx>
>> ---
>> include/uapi/linux/io_uring.h | 1 +
>> io_uring/timeout.c | 59 +++++++++++++++++++++++++++++++++--
>> 2 files changed, 57 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
>> index f8d14d1c58d3..0716cb17e436 100644
>> --- a/include/uapi/linux/io_uring.h
>> +++ b/include/uapi/linux/io_uring.h
>> @@ -250,6 +250,7 @@ enum io_uring_op {
>> #define IORING_TIMEOUT_REALTIME (1U << 3)
>> #define IORING_LINK_TIMEOUT_UPDATE (1U << 4)
>> #define IORING_TIMEOUT_ETIME_SUCCESS (1U << 5)
>> +#define IORING_TIMEOUT_MULTISHOT (1U << 6)
>> #define IORING_TIMEOUT_CLOCK_MASK (IORING_TIMEOUT_BOOTTIME | IORING_TIMEOUT_REALTIME)
>> #define IORING_TIMEOUT_UPDATE_MASK (IORING_TIMEOUT_UPDATE | IORING_LINK_TIMEOUT_UPDATE)
>> /*
>> diff --git a/io_uring/timeout.c b/io_uring/timeout.c
>> index 5c6c6f720809..61b8488565ce 100644
> ...
>> +static void io_timeout_complete(struct io_kiocb *req, struct io_tw_state *ts)
>> +{
>> + struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
>> + struct io_timeout_data *data = req->async_data;
>> + struct io_ring_ctx *ctx = req->ctx;
>> +
>> + if (!io_timeout_finish(timeout, data)) {
>> + bool filled;
>> + filled = io_aux_cqe(ctx, false, req->cqe.user_data, -ETIME,
>> + IORING_CQE_F_MORE, false);
>> + if (filled) {
>> + /* re-arm timer */
>> + spin_lock_irq(&ctx->timeout_lock);
>> + list_add(&timeout->list, ctx->timeout_list.prev);
>> + data->timer.function = io_timeout_fn;
>> + hrtimer_start(&data->timer, timespec64_to_ktime(data->ts), data->mode);
>> + spin_unlock_irq(&ctx->timeout_lock);
>> + return;
>> + }
>> + io_req_set_res(req, -EOVERFLOW, 0);
>
> Let's not change the return value. It's considered a normal completion
> and we don't change the code for them. And there is IORING_CQE_F_MORE
> for userspace to figure out that it has been terminated.
Makes sense. I'll keep the return value as-is.
>
>
>> + }
>> +
>> + io_req_task_complete(req, ts);
>> +}
>> +
>> static bool io_kill_timeout(struct io_kiocb *req, int status)
>> __must_hold(&req->ctx->timeout_lock)
>> {
>> @@ -212,7 +253,7 @@ static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
>> req_set_fail(req);
>> io_req_set_res(req, -ETIME, 0);
>> - req->io_task_work.func = io_req_task_complete;
>> + req->io_task_work.func = io_timeout_complete;
>> io_req_task_work_add(req);
>> return HRTIMER_NORESTART;
>> }
>> @@ -470,16 +511,28 @@ static int __io_timeout_prep(struct io_kiocb *req,
>> return -EINVAL;
>> flags = READ_ONCE(sqe->timeout_flags);
>> if (flags & ~(IORING_TIMEOUT_ABS | IORING_TIMEOUT_CLOCK_MASK |
>> - IORING_TIMEOUT_ETIME_SUCCESS))
>> + IORING_TIMEOUT_ETIME_SUCCESS |
>> + IORING_TIMEOUT_MULTISHOT)) {
>> return -EINVAL;
>> + }
>
> Please, don't add braces, they're not needed here.
Thanks, will remove.
>
>> /* more than one clock specified is invalid, obviously */
>> if (hweight32(flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
>> return -EINVAL;
>> + /* multishot requests only make sense with rel values */
>> + if (!(~flags & (IORING_TIMEOUT_MULTISHOT | IORING_TIMEOUT_ABS)))
>> + return -EINVAL;
>> INIT_LIST_HEAD(&timeout->list);
>> timeout->off = off;
>> if (unlikely(off && !req->ctx->off_timeout_used))
>> req->ctx->off_timeout_used = true;
>> + /*
>> + * for multishot reqs w/ fixed nr of repeats, target_seq tracks the
>> + * remaining nr
>> + */
>> + timeout->repeats = 0;
>> + if ((flags & IORING_TIMEOUT_MULTISHOT) && off > 0)
>> + timeout->repeats = off;
>> if (WARN_ON_ONCE(req_has_async_data(req)))
>> return -EFAULT;
>
