Re: [PATCH for-next 4/4] RDMA/efa: CQ notifications

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Aug 11, 2021 at 06:11:31PM +0300, Gal Pressman wrote:
> diff --git a/drivers/infiniband/hw/efa/efa_main.c b/drivers/infiniband/hw/efa/efa_main.c
> index 417dea5f90cf..29db4dec02f0 100644
> +++ b/drivers/infiniband/hw/efa/efa_main.c
> @@ -67,6 +67,46 @@ static void efa_release_bars(struct efa_dev *dev, int bars_mask)
>  	pci_release_selected_regions(pdev, release_bars);
>  }
>  
> +static void efa_process_comp_eqe(struct efa_dev *dev, struct efa_admin_eqe *eqe)
> +{
> +	u16 cqn = eqe->u.comp_event.cqn;
> +	struct efa_cq *cq;
> +
> +	cq = xa_load(&dev->cqs_xa, cqn);
> +	if (unlikely(!cq)) {

This seems unlikely to be correct, what prevents cq from being
destroyed concurrently?

A comp_handler cannot be running after cq destroy completes.

> @@ -421,6 +551,7 @@ static struct efa_dev *efa_probe_device(struct pci_dev *pdev)
>  	edev->efa_dev = dev;
>  	edev->dmadev = &pdev->dev;
>  	dev->pdev = pdev;
> +	xa_init_flags(&dev->cqs_xa, XA_FLAGS_LOCK_IRQ);

And this is confusing too, since the above is the only reference and
doesn't take the xa_lock why does the xa need to use LOCK_IRQ?

Jason