Re: [PATCH] RDMA/rxe: Restore tasklet call for rxe_cq.c

[Honggang LI <honggangli@163.com>]

On Thu, Jul 11, 2024 at 03:46:24PM +0200, Zhu Yanjun wrote:
> Subject: Re: [PATCH] RDMA/rxe: Restore tasklet call for rxe_cq.c
> > 
> > > Please explain the deadlock in details.
> 
> I read the discussion carefully. I have the following:
> 1). This problem is not from RXE. It seems to be related with krping
> modules. As such, the root cause is not in RXE. It is not good to fix this
> problem in RXE.

Can't say it a problem in krping. As krping works over irdma/mlx5/siw.
The deadlock only happens with rxe.

> 
> 2). In the kernel upstream, tasklet is marked obsolete and has some design
> flaws. So replacing workqueue with tasklet in RXE does not keep up with the
> kernel upstream.
> 
> https://patchwork.kernel.org/project/linux-rdma/cover/20240621050525.3720069-1-allen.lkml@gmail.com/
> In this link, there are some work to replace tasklet with BH workqueue.
> As such, it is not good to replace workqueue with tasklet.

Yes, you are right. Tasklet is obsoleted. We need a better solution for
this issue. Please feel free to drop the patch.