Re: io_uring process termination/killing is not working

[Jens Axboe <axboe@kernel.dk>]

On 8/13/20 10:07 AM, Josef wrote:
> On Thu, 13 Aug 2020 at 01:32, Jens Axboe <axboe@kernel.dk> wrote:
>> Yeah I think you're right. How about something like the below? That'll
>> potentially cancel more than just the one we're looking for, but seems
>> kind of silly to only cancel from the file table holding request and to
>> the end.
>>
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 8a2afd8c33c9..0630a9622baa 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -4937,6 +5003,7 @@ static bool io_poll_remove_one(struct io_kiocb *req)
>>                 io_cqring_fill_event(req, -ECANCELED);
>>                 io_commit_cqring(req->ctx);
>>                 req->flags |= REQ_F_COMP_LOCKED;
>> +               req_set_fail_links(req);
>>                 io_put_req(req);
>>         }
>>
>> @@ -7935,6 +8002,47 @@ static bool io_wq_files_match(struct io_wq_work *work, void *data)
>>         return work->files == files;
>>  }
>>
>> +static bool __io_poll_remove_link(struct io_kiocb *preq, struct io_kiocb *req)
>> +{
>> +       struct io_kiocb *link;
>> +
>> +       if (!(preq->flags & REQ_F_LINK_HEAD))
>> +               return false;
>> +
>> +       list_for_each_entry(link, &preq->link_list, link_list) {
>> +               if (link != req)
>> +                       break;
>> +               io_poll_remove_one(preq);
>> +               return true;
>> +       }
>> +
>> +       return false;
>> +}
>> +
>> +/*
>> + * We're looking to cancel 'req' because it's holding on to our files, but
>> + * 'req' could be a link to another request. See if it is, and cancel that
>> + * parent request if so.
>> + */
>> +static void io_poll_remove_link(struct io_ring_ctx *ctx, struct io_kiocb *req)
>> +{
>> +       struct hlist_node *tmp;
>> +       struct io_kiocb *preq;
>> +       int i;
>> +
>> +       spin_lock_irq(&ctx->completion_lock);
>> +       for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
>> +               struct hlist_head *list;
>> +
>> +               list = &ctx->cancel_hash[i];
>> +               hlist_for_each_entry_safe(preq, tmp, list, hash_node) {
>> +                       if (__io_poll_remove_link(preq, req))
>> +                               break;
>> +               }
>> +       }
>> +       spin_unlock_irq(&ctx->completion_lock);
>> +}
>> +
>>  static void io_uring_cancel_files(struct io_ring_ctx *ctx,
>>                                   struct files_struct *files)
>>  {
>> @@ -7989,6 +8097,8 @@ static void io_uring_cancel_files(struct io_ring_ctx *ctx,
>>                         }
>>                 } else {
>>                         io_wq_cancel_work(ctx->io_wq, &cancel_req->work);
>> +                       /* could be a link, check and remove if it is */
>> +                       io_poll_remove_link(ctx, cancel_req);
>>                         io_put_req(cancel_req);
>>                 }
>>
>>
> 
> btw it works for me thanks

Thanks for testing, I've committed an updated version that also ensures
we find timeout based links:

https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.9&id=f254ac04c8744cf7bfed012717eac34eacc65dfb

-- 
Jens Axboe