Re: [dpdk-stable] [PATCH 19.11] net/mlx5: fix incorrect r/w lock usage in DMA unmap

[Christian Ehrhardt <christian.ehrhardt@canonical.com>]

On Wed, Aug 11, 2021 at 10:31 AM Feifei Wang <feifei.wang2@arm.com> wrote:
>
> [ upstream commit 1c196da274b82e6f1642bde7b1c407a2066caee1 ]
>
> For mlx5 DMA unmap, write lock should be used for rebuilding memory
> region cache table rather than read lock.

Thank you, applied to the WIP 19.11 branch

> Fixes: 989e999d9305 ("net/mlx5: support PCI device DMA map and unmap")
> Cc: shahafs@mellanox.com
> Cc: stable@dpdk.org
>
> Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
> ---
>  drivers/net/mlx5/mlx5_mr.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/mlx5/mlx5_mr.c b/drivers/net/mlx5/mlx5_mr.c
> index 54a11bd5d1..71c2254c91 100644
> --- a/drivers/net/mlx5/mlx5_mr.c
> +++ b/drivers/net/mlx5/mlx5_mr.c
> @@ -1397,10 +1397,10 @@ mlx5_dma_unmap(struct rte_pci_device *pdev, void *addr,
>         }
>         priv = dev->data->dev_private;
>         sh = priv->sh;
> -       rte_rwlock_read_lock(&sh->mr.rwlock);
> +       rte_rwlock_write_lock(&sh->mr.rwlock);
>         mr = mr_lookup_dev_list(sh, &entry, (uintptr_t)addr);
>         if (!mr) {
> -               rte_rwlock_read_unlock(&sh->mr.rwlock);
> +               rte_rwlock_write_unlock(&sh->mr.rwlock);
>                 DRV_LOG(WARNING, "address 0x%" PRIxPTR " wasn't registered "
>                                  "to PCI device %p", (uintptr_t)addr,
>                                  (void *)pdev);
> @@ -1424,7 +1424,7 @@ mlx5_dma_unmap(struct rte_pci_device *pdev, void *addr,
>         ++sh->mr.dev_gen;
>         DEBUG("broadcasting local cache flush, gen=%d", sh->mr.dev_gen);
>         rte_smp_wmb();
> -       rte_rwlock_read_unlock(&sh->mr.rwlock);
> +       rte_rwlock_write_unlock(&sh->mr.rwlock);
>         return 0;
>  }
>
> --
> 2.25.1
>


-- 
Christian Ehrhardt
Staff Engineer, Ubuntu Server
Canonical Ltd