ACK: [SRU][I][J][PATCH 1/1] s390/cio: verify the driver availability for path_event call

[Stefan Bader]

On 16.02.22 10:58, Krzysztof Kozlowski wrote:
> From: Vineeth Vijayan <vneethv at linux.ibm.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1960875
> 
> If no driver is attached to a device or the driver does not provide the
> path_event function, an FCES path-event on this device could end up in a
> kernel-panic. Verify the driver availability before the path_event
> function call.
> 
> Fixes: 32ef938815c1 ("s390/cio: Add support for FCES status notification")
> Cc: stable at vger.kernel.org
> Signed-off-by: Vineeth Vijayan <vneethv at linux.ibm.com>
> Suggested-by: Peter Oberparleiter <oberpar at linux.ibm.com>
> Reviewed-by: Jan Hoeppner <hoeppner at linux.ibm.com>
> Reviewed-by: Peter Oberparleiter <oberpar at linux.ibm.com>
> Signed-off-by: Vasily Gorbik <gor at linux.ibm.com>
> (cherry picked from commit dd9cb842fa9d90653a9b48aba52f89c069f3bc50)
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>   drivers/s390/cio/device.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
> index 84f659cafe76..ab734b66d008 100644
> --- a/drivers/s390/cio/device.c
> +++ b/drivers/s390/cio/device.c
> @@ -1208,7 +1208,7 @@ static int io_subchannel_chp_event(struct subchannel *sch,
>   			else
>   				path_event[chpid] = PE_NONE;
>   		}
> -		if (cdev)
> +		if (cdev && cdev->drv && cdev->drv->path_event)
>   			cdev->drv->path_event(cdev, path_event);
>   		break;
>   	}

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