Re: [PATCH] io_uring: cancel all requests on task exit

[Jens Axboe <axboe@kernel.dk>]

On 1/17/21 3:52 AM, Pavel Begunkov wrote:
> On 17/01/2021 04:04, Jens Axboe wrote:
>> We used to have task exit tied to canceling files_struct ownership, but we
>> really should just simplify this and cancel any request that the task has
>> pending when it exits. Instead of handling files ownership specially, we
>> do the same regardless of request type.
>>
>> This can be further simplified in the next major kernel release, unifying
>> how we cancel across exec and exit.
> 
> Looks good in general. See a comment below, but otherwise
> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
> 
> btw, I wonder if we can incite syzbot to try to break it.
> 
>>
>> Cc: stable@vger.kernel.org # 5.9+
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>>
>> ---
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 383ff6ed3734..1190296fc95f 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -9029,7 +9029,7 @@ static void io_uring_remove_task_files(struct io_uring_task *tctx)
>>  		io_uring_del_task_file(file);
>>  }
>>  
>> -void __io_uring_files_cancel(struct files_struct *files)
>> +static void __io_uring_files_cancel(void)
>>  {
>>  	struct io_uring_task *tctx = current->io_uring;
>>  	struct file *file;
>> @@ -9038,11 +9038,10 @@ void __io_uring_files_cancel(struct files_struct *files)
>>  	/* make sure overflow events are dropped */
>>  	atomic_inc(&tctx->in_idle);
>>  	xa_for_each(&tctx->xa, index, file)
>> -		io_uring_cancel_task_requests(file->private_data, files);
>> +		io_uring_cancel_task_requests(file->private_data, NULL);
>>  	atomic_dec(&tctx->in_idle);
>>  
>> -	if (files)
>> -		io_uring_remove_task_files(tctx);
>> +	io_uring_remove_task_files(tctx);
> 
> This restricts cancellations to only one iteration. Just delete it,
> __io_uring_task_cancel() calls it already.

Ah indeed, makes it even better. I removed it, thanks.

-- 
Jens Axboe