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

[Jens Axboe <axboe@kernel.dk>]

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?

-- 
Jens Axboe