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

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

[Vaibhav Jain]

commit 12841f87b7a8ceb3d54f171660f72a86941bfcb3 upstream, for 4.9.

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: 9e8df8a21963 ("cxl: EEH support")
Cc: stable@vger.kernel.org
Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
Changelog:
Rebased the upstream patch over stable 4.9 tree
---
 drivers/misc/cxl/pci.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index eef202d4399b..a5422f483ad5 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1758,6 +1758,9 @@ 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;
@@ -1801,6 +1804,11 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
 			/* Only participate in EEH if we are on a virtual PHB */
 			if (afu->phb == NULL)
 				return PCI_ERS_RESULT_NONE;
+
+			/*
+			 * Tell the AFU drivers; but we don't care what they
+			 * say, we're going away.
+			 */
 			cxl_vphb_error_detected(afu, state);
 		}
 		return PCI_ERS_RESULT_DISCONNECT;
@@ -1941,6 +1949,9 @@ 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
@@ -2003,6 +2014,9 @@ 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)
-- 
2.14.3

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

[Greg KH]

On Wed, Dec 20, 2017 at 03:07:06PM +0530, Vaibhav Jain wrote:
> commit 12841f87b7a8ceb3d54f171660f72a86941bfcb3 upstream, for 4.9.

Thanks, do we also need this for 4.4?  If so, can you provide a
backport?

thanks,

greg k-h

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

[Vaibhav Jain]

Greg KH <greg@kroah.com> writes:

> On Wed, Dec 20, 2017 at 03:07:06PM +0530, Vaibhav Jain wrote:
>> commit 12841f87b7a8ceb3d54f171660f72a86941bfcb3 upstream, for 4.9.
>
> Thanks, do we also need this for 4.4?  If so, can you provide a
> backport?
>
Thanks Greg for applying this patch on 4.9 stable tree. I have done a
back-port for 4.3+ and will send the back-ported-patch across.

Cheers,
-- 
Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Linux Technology Center, IBM India Pvt. Ltd.

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

[Vaibhav Jain]

commit 12841f87b7a8ceb3d54f171660f72a86941bfcb3 upstream, for 4.3.

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: 9e8df8a21963 ("cxl: EEH support")
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
Changelog:
- Rebased the patch on 4.3 stable tree
---
 drivers/misc/cxl/pci.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index 85761d7eb333..b982329f3837 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1328,6 +1328,9 @@ 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;
@@ -1368,6 +1371,10 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
 		 */
 		for (i = 0; i < adapter->slices; i++) {
 			afu = adapter->afu[i];
+			/*
+			 * Tell the AFU drivers; but we don't care what they
+			 * say, we're going away.
+			 */
 			cxl_vphb_error_detected(afu, state);
 		}
 		return PCI_ERS_RESULT_DISCONNECT;
@@ -1491,6 +1498,9 @@ 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;
+
 		cxl_pci_vphb_reconfigure(afu);
 
 		list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) {
@@ -1555,6 +1565,9 @@ 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)
-- 
2.14.3

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

[Greg KH]

On Thu, Dec 21, 2017 at 09:36:19AM +0530, Vaibhav Jain wrote:
> commit 12841f87b7a8ceb3d54f171660f72a86941bfcb3 upstream, for 4.3.

Thanks, now applied to 4.4.

greg k-h