Re: [PATCH net-next V2 10/13] net: devmem: add netdev_has_dmabuf_binding() helper

[sashiko-bot@kernel.org]

> From: Dragos Tatulea <dtatulea@nvidia.com>
> 
> Currently there is no way to check whether a dmabuf is bound on a TX
> queue. RX side has netif_rxq_has_unreadable_mp() which gives a hint
> of it.
> 
> To help with that, add a helper to check whether a devmem dmabuf
> binding may still be in use on a given netdev, optionally filtered by
> the DMA device the dmabuf was mapped against.
> 
> A binding can outlive the user's unbind: it can still be referenced by
> in-flight TX skbs, whose DMA mappings are only valid for the device the
> dmabuf was attached to. Reporting such a binding as gone would let a
> driver swap the DMA device out from under those skbs. Bindings stay in
> the bindings xarray until they are freed, so walk it and report every
> binding of the netdev that is still mapped. Bindings that were already
> unmapped are not reported.
> 
> This API is necessary for the upcoming support of data direct in mlx5e.
> 
> Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
> Cc: Bobby Eshleman <bobbyeshleman@gmail.com>
> Signed-off-by: Tariq Toukan <tariqt@nvidia.com>

Sashiko has reviewed this patch and found no issues.

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