Re: [PATCH rdma-next] RDMA/mlx5: Add a umr recovery flow

[Leon Romanovsky <leon@kernel.org>]

On Thu, May 26, 2022 at 02:21:32PM -0300, Jason Gunthorpe wrote:
> On Thu, May 26, 2022 at 07:29:20PM +0300, Leon Romanovsky wrote:
> 
> > > > +		err = mlx5r_umr_post_send(umrc->qp, mkey, &umr_context.cqe, wqe,
> > > > +					  with_data);
> > > > +		mutex_unlock(&umrc->lock);
> > > > +		if (err) {
> > > > +			mlx5_ib_warn(dev, "UMR post send failed, err %d\n",
> > > > +				     err);
> > > > +			break;
> > > >  		}
> > > > +
> > > > +		wait_for_completion(&umr_context.done);
> > > 
> > > Nor is sleeping under a semaphore.
> > 
> > Not according to the kernel/locking/semaphore.c. Semaphores can sleep
> > and the code protected by semaphores can sleep too.
> > 
> >    53 void down(struct semaphore *sem)
> >    54 {
> >    55         unsigned long flags;
> >    56
> >    57         might_sleep();
> >    ....
> >    64 }
> >    65 EXPORT_SYMBOL(down);
> 
> Hum, OK, I am confused
> 
> > > And, I'm pretty sure, this entire function is called under a spinlock
> > > in some cases.
> >
> > Can you point to such flow?
> 
> It seems like not anymore, or at least I couldn't find a case.

So are we fine with this patch and it can go as is after merge window?

Thanks

> 
> Jason