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

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

On 22/11/17 16:46, Vaibhav Jain wrote:
> During an eeh a kernel-oops is reported if no vPHB to 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.
> 
> Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>

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

Looks to me like we might need the same fix in 
cxl_vphb_error_detected()? It's called twice in 
cxl_pci_error_detected(), and in only one of those cases is it 
surrounded by an afu->phb NULL check.

> ---
>   drivers/misc/cxl/pci.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
> index bb7fd3f4edab..80ac40cdc31b 100644
> --- a/drivers/misc/cxl/pci.c
> +++ b/drivers/misc/cxl/pci.c
> @@ -2265,6 +2265,9 @@ 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 +2330,9 @@ 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@au1.ibm.com  IBM Australia Limited