Re: [PATCH 0/5] fixes for REQ_F_COMP_LOCKED

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

On 13/10/2020 09:43, Pavel Begunkov wrote:
> This removes REQ_F_COMP_LOCKED to fix a couple of problems with it.
> 
> [5/5] is harsh and some work should be done to ease the aftermath,
> i.e. io_submit_flush_completions() and maybe fail_links().
> 
> Another way around would be to replace the flag with an comp_locked
> argument in put_req(), free_req() and so on, but IMHO in a long run
> removing it should be better.
> 
> note: there is a new io_req_task_work_add() call in [5/5]. Jens,
> could you please verify whether passed @twa_signal_ok=true is ok,
> because I don't really understand the difference.

btw, when I copied task_work_add(TWA_RESUME) from __io_free_req(),
tasks were hanging sleeping uninterruptibly, and fail_links()
wasn't waking them. It looks like the deferring branch of
__io_free_req() is buggy as well and should use
io_req_task_work_add().


> 
> Pavel Begunkov (5):
>   io_uring: don't set COMP_LOCKED if won't put
>   io_uring: don't unnecessarily clear F_LINK_TIMEOUT
>   io_uring: don't put a poll req under spinlock
>   io_uring: dig out COMP_LOCK from deep call chain
>   io_uring: fix REQ_F_COMP_LOCKED by killing it
> 
>  fs/io_uring.c | 158 ++++++++++++++++++--------------------------------
>  1 file changed, 57 insertions(+), 101 deletions(-)
> 

-- 
Pavel Begunkov