Re: [PATCH net v3] net: sched: fix packet stuck problem for lockless qdisc

On 2021/4/13 11:26, Hillf Danton wrote:

On Tue, 13 Apr 2021 10:56:42 Yunsheng Lin wrote:

quoted

On 2021/4/13 10:21, Hillf Danton wrote:

quoted

On Mon, 12 Apr 2021 20:00:43  Yunsheng Lin wrote:

quoted

Yes, the below patch seems to fix the data race described in
the commit log.
Then what is the difference between my patch and your patch below:)

Hehe, this is one of the tough questions over a bounch of weeks.

If a seqcount can detect the race between skb enqueue and dequeue then we
cant see any excuse for not rolling back to the point without NOLOCK.

I am not sure I understood what you meant above.

As my understanding, the below patch is essentially the same as
your previous patch, the only difference I see is it uses qdisc->pad
instead of __QDISC_STATE_NEED_RESCHEDULE.

So instead of proposing another patch, it would be better if you
comment on my patch, and make improvement upon that.

Happy to do that after you show how it helps revert NOLOCK.

Actually I am not going to revert NOLOCK, but add optimization
to it if the patch fixes the packet stuck problem.

Is there any reason why you want to revert it?

.