Re: [PATCH 3/3] io_uring: move struct io_kiocb from task_struct to io_uring_task

[Pavel Begunkov <asml.silence@gmail.com>]

On 11/3/24 21:54, Jens Axboe wrote:
> On 11/3/24 2:47 PM, Pavel Begunkov wrote:
>> On 11/3/24 17:49, Jens Axboe wrote:
>> ...
>>> diff --git a/include/linux/io_uring/cmd.h b/include/linux/io_uring/cmd.h
>> ...
>>>        nd->head = prev_nd->head;
>>> @@ -115,7 +115,7 @@ struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx)
>>>        notif->opcode = IORING_OP_NOP;
>>>        notif->flags = 0;
>>>        notif->file = NULL;
>>> -    notif->task = current;
>>> +    notif->tctx = current->io_uring;
>>>        io_get_task_refs(1);
>>>        notif->file_node = NULL;
>>>        notif->buf_node = NULL;
>>> diff --git a/io_uring/poll.c b/io_uring/poll.c
>>> index 7db3010b5733..56332893a4b0 100644
>>> --- a/io_uring/poll.c
>>> +++ b/io_uring/poll.c
>>> @@ -224,8 +224,7 @@ static int io_poll_check_events(struct io_kiocb *req, struct io_tw_state *ts)
>>>    {
>>>        int v;
>>>    -    /* req->task == current here, checking PF_EXITING is safe */
>>> -    if (unlikely(req->task->flags & PF_EXITING))
>>> +    if (unlikely(current->flags & PF_EXITING))
>>>            return -ECANCELED
>>
>> Unlike what the comment says, req->task doesn't have to match current,
>> in which case the new check does nothing and it'll break in many very
>> interesting ways.
> 
> In which cases does it not outside of fallback?

I think it can only be fallback path

-- 
Pavel Begunkov