On Thu, May 26, 2022 at 11:32:12AM -0300, Jason Gunthorpe wrote:
> On Sun, May 15, 2022 at 07:19:53AM +0300, Leon Romanovsky wrote:
> > @@ -270,17 +296,49 @@ static int mlx5r_umr_post_send_wait(struct mlx5_ib_dev *dev, u32 mkey,
> > mlx5r_umr_init_context(&umr_context);
> >
> > down(&umrc->sem);
> > + while (true) {
> > + mutex_lock(&umrc->lock);
>
> You need to test this with lockdep, nesing a mutex under a semaphor is
> not allowed, AFAIK.
We are running with lockdep all our tests.
>
> > + 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);
>
> And, I'm pretty sure, this entire function is called under a spinlock
> in some cases.
Can you point to such flow?
Thanks
>
> Jason
