[PATCH v3] cxl: Check if vphb exists before iterating over AFU devices

[Andrew Donnellan]

On 23/11/17 14:38, Vaibhav Jain wrote:
> During an eeh a kernel-oops is reported if no vPHB is allocated to the
> AFU. This happens as during AFU init, an error in creation of vPHB is
> a non-fatal error. Hence afu->phb should always be checked for NULL
> before iterating over it for the virtual AFU pci devices.
> 
> This patch fixes the kenel-oops by adding a NULL pointer check for
> afu->phb before it is dereferenced.
> 
> Fixes: 9e8df8a2196("cxl: EEH support")
> Cc: stable at vger.kernel.org
> Signed-off-by: Vaibhav Jain <vaibhav at linux.vnet.ibm.com>

Thanks for fixing it!

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

> ---
> Changelog:
> 
> v3	-> Fixed a reverse NULL check [Fred]
> 
> Resend 	-> Added the 'Fixes' info and marking the patch to stable tree [Mpe]
> 
> v2     	-> Added the vphb NULL check to cxl_vphb_error_detected() [Andrew]
> ---
>   drivers/misc/cxl/pci.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
> index bb7fd3f4edab..19969ee86d6f 100644
> --- a/drivers/misc/cxl/pci.c
> +++ b/drivers/misc/cxl/pci.c
> @@ -2083,6 +2083,9 @@ static pci_ers_result_t cxl_vphb_error_detected(struct cxl_afu *afu,
>   	/* There should only be one entry, but go through the list
>   	 * anyway
>   	 */
> +	if (afu->phb == NULL)
> +		return result;
> +
>   	list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) {
>   		if (!afu_dev->driver)
>   			continue;
> @@ -2124,8 +2127,7 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
>   			 * Tell the AFU drivers; but we don't care what they
>   			 * say, we're going away.
>   			 */
> -			if (afu->phb != NULL)
> -				cxl_vphb_error_detected(afu, state);
> +			cxl_vphb_error_detected(afu, state);
>   		}
>   		return PCI_ERS_RESULT_DISCONNECT;
>   	}
> @@ -2265,6 +2267,9 @@ static pci_ers_result_t cxl_pci_slot_reset(struct pci_dev *pdev)
>   		if (cxl_afu_select_best_mode(afu))
>   			goto err;
> 
> +		if (afu->phb == NULL)
> +			continue;
> +
>   		list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) {
>   			/* Reset the device context.
>   			 * TODO: make this less disruptive
> @@ -2327,6 +2332,9 @@ static void cxl_pci_resume(struct pci_dev *pdev)
>   	for (i = 0; i < adapter->slices; i++) {
>   		afu = adapter->afu[i];
> 
> +		if (afu->phb == NULL)
> +			continue;
> +
>   		list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) {
>   			if (afu_dev->driver && afu_dev->driver->err_handler &&
>   			    afu_dev->driver->err_handler->resume)
> 

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