netdev - Re: [PATCH v9 09/27] sfc: request cxl ram resource

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Message-ID: <678b0adea8dfe_20fa294c@dwillia2-xfh.jf.intel.com.notmuch>
Date: Fri, 17 Jan 2025 17:58:54 -0800
From: Dan Williams <dan.j.williams@...el.com>
To: <alejandro.lucero-palau@....com>, <linux-cxl@...r.kernel.org>,
	<netdev@...r.kernel.org>, <dan.j.williams@...el.com>, <edward.cree@....com>,
	<davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<edumazet@...gle.com>, <dave.jiang@...el.com>
CC: Alejandro Lucero <alucerop@....com>
Subject: Re: [PATCH v9 09/27] sfc: request cxl ram resource

alejandro.lucero-palau@ wrote:
> From: Alejandro Lucero <alucerop@....com>
> 
> Use cxl accessor for obtaining the ram resource the device advertises.
> 
> Signed-off-by: Alejandro Lucero <alucerop@....com>
> Reviewed-by: Martin Habets <habetsm.xilinx@...il.com>
> Reviewed-by: Fan Ni <fan.ni@...sung.com>
> Acked-by: Edward Cree <ecree.xilinx@...il.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
>  drivers/net/ethernet/sfc/efx_cxl.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/net/ethernet/sfc/efx_cxl.c b/drivers/net/ethernet/sfc/efx_cxl.c
> index 29368d010adc..2031f08ee689 100644
> --- a/drivers/net/ethernet/sfc/efx_cxl.c
> +++ b/drivers/net/ethernet/sfc/efx_cxl.c
> @@ -85,6 +85,12 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>  		goto err_resource_set;
>  	}
>  
> +	rc = cxl_request_resource(cxl->cxlds, CXL_RES_RAM);
> +	if (rc) {
> +		pci_err(pci_dev, "CXL request resource failed");
> +		goto err_resource_set;
> +	}
> +
>  	probe_data->cxl = cxl;
>  
>  	return 0;
> @@ -99,6 +105,7 @@ int efx_cxl_init(struct efx_probe_data *probe_data)
>  void efx_cxl_exit(struct efx_probe_data *probe_data)
>  {
>  	if (probe_data->cxl) {
> +		cxl_release_resource(probe_data->cxl->cxlds, CXL_RES_RAM);

Given that the DPA layout is a static property of 'struct cxl_dev_state'
once set there is no need to release it. Notice how there is no release
in the memdev case either. The 'release' is freeing @cxlds.

Now, any DPA reservations from that partition need to be released, but
those releases are with respect to cxl_dpa_{alloc,free}().