On 17/01/2021 02:13, Jens Axboe wrote:
> On 1/16/21 4:37 PM, Pavel Begunkov wrote:
>> If there are no requests at the time __io_uring_task_cancel() is called,
>> tctx_inflight() returns zero and and it terminates not getting a chance
>> to go through __io_uring_files_cancel() and do
>> io_disable_sqo_submit(). And we absolutely want them disabled by the
>> time cancellation ends.
>>
>> Also a fix potential false positive warning because of ctx->sq_data
>> check before io_disable_sqo_submit().
>>
>> Reported-by: Jens Axboe <axboe@xxxxxxxxx>
>> Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
>> ---
>>
>> To not grow diffstat now will be cleaned for-next
>>
>> fs/io_uring.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index d494c4269fc5..0d50845f1f3f 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -8937,10 +8937,12 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx,
>> {
>> struct task_struct *task = current;
>>
>> - if ((ctx->flags & IORING_SETUP_SQPOLL) && ctx->sq_data) {
>> + if (ctx->flags & IORING_SETUP_SQPOLL) {
>> /* for SQPOLL only sqo_task has task notes */
>> WARN_ON_ONCE(ctx->sqo_task != current);
>> io_disable_sqo_submit(ctx);
>> + }
>> + if ((ctx->flags & IORING_SETUP_SQPOLL) && ctx->sq_data) {
>> task = ctx->sq_data->thread;
>> atomic_inc(&task->io_uring->in_idle);
>> io_sq_thread_park(ctx->sq_data);
>
> Maybe just nest that inside?
>
> if (ctx->flags & IORING_SETUP_SQPOLL) {
> /* for SQPOLL only sqo_task has task notes */
> WARN_ON_ONCE(ctx->sqo_task != current);
> io_disable_sqo_submit(ctx);
> if (ctx->sq_data) {
> ...
> }
> }
>
> That'd look a bit cleaner imho.
second thought, it can't even happen because if not set we failed
during creation, and it has its own disable hooks.
sent v2 without that part
--
Pavel Begunkov
