Re: [PATCH v2] ocxl: Fix endiannes bug in read_afu_name()

[Andrew Donnellan <andrew.donnellan@au1.ibm.com>]

On 12/12/18 4:58 am, Greg Kurz wrote:
> The AFU Descriptor Template in the PCI config space has a Name Space
> field which is a 24 Byte ASCII character string of descriptive name
> space for the AFU. The OCXL driver read the string four characters at
> a time with pci_read_config_dword().
> 
> This optimization is valid on a little-endian system since this is PCI,
> but a big-endian system ends up with each subset of four characters in
> reverse order.
> 
> This could be fixed by switching to read characters one by one. Another
> option is to swap the bytes if we're big-endian.
> 
> Go for the latter with le32_to_cpu().
> 
> Cc: stable@vger.kernel.org      # v4.16
> Signed-off-by: Greg Kurz <groug@kaod.org>
> Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>

Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

> ---
> v2: - silence sparse with (__force __le32) cast
>      - new changelog
> ---
>   drivers/misc/ocxl/config.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/ocxl/config.c b/drivers/misc/ocxl/config.c
> index 57a6bb1fd3c9..8f2c5d8bd2ee 100644
> --- a/drivers/misc/ocxl/config.c
> +++ b/drivers/misc/ocxl/config.c
> @@ -318,7 +318,7 @@ static int read_afu_name(struct pci_dev *dev, struct ocxl_fn_config *fn,
>   		if (rc)
>   			return rc;
>   		ptr = (u32 *) &afu->name[i];
> -		*ptr = val;
> +		*ptr = le32_to_cpu((__force __le32) val);
>   	}
>   	afu->name[OCXL_AFU_NAME_SZ - 1] = '\0'; /* play safe */
>   	return 0;
> 

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited