> 2019年10月11日 10:35，Jens Axboe <axboe@xxxxxxxxx> 写道：
>
> On 10/10/19 8:24 PM, yangerkun wrote:
>>
>>
>> On 2019/10/9 9:19, Jackie Liu wrote:
>>> __io_get_deferred_req is used to get all defer lists, including defer_list
>>> and timeout_list, but io_sequence_defer should be only cares about the sequence.
>>>
>>> Signed-off-by: Jackie Liu <liuyun01@xxxxxxxxxx>
>>> ---
>>> fs/io_uring.c | 13 +++++--------
>>> 1 file changed, 5 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>> index 8a0381f1a43b..8ec2443eb019 100644
>>> --- a/fs/io_uring.c
>>> +++ b/fs/io_uring.c
>>> @@ -418,9 +418,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
>>> static inline bool io_sequence_defer(struct io_ring_ctx *ctx,
>>> struct io_kiocb *req)
>>> {
>>> - /* timeout requests always honor sequence */
>>> - if (!(req->flags & REQ_F_TIMEOUT) &&
>>> - (req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
>>> + if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
>>> return false;
>>>
>>> return req->sequence != ctx->cached_cq_tail + ctx->rings->sq_dropped;
>>> @@ -435,12 +433,11 @@ static struct io_kiocb *__io_get_deferred_req(struct io_ring_ctx *ctx,
>>> return NULL;
>>>
>>> req = list_first_entry(list, struct io_kiocb, list);
>>> - if (!io_sequence_defer(ctx, req)) {
>>> - list_del_init(&req->list);
>>> - return req;
>>> - }
>>> + if (!(req->flags & REQ_F_TIMEOUT) && io_sequence_defer(ctx, req))
>>> + return NULL;
>> Hi,
>>
>> For timeout req, we should also compare the sequence to determine to
>> return NULL or the req. But now we will return req directly. Actually,
>> no need to compare req->flags with REQ_F_TIMEOUT.
>
> Yes, not sure how I missed this, the patch is broken as-is. I will kill
> it, cleanup can be done differently.
Sorry for miss it, I don't wanna change the logic, it's not my original meaning.
Personal opinion, timeout list should not be mixed with defer_list, which makes
the code more complicated and difficult to understand.
--
BR, Jackie Liu
