Patch "drivers/pci/hotplug: Handle presence detection change properly" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

drivers/pci/hotplug: Handle presence detection change properly

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drivers-pci-hotplug-handle-presence-detection-change-properly.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Gavin Shan <[email protected]>
Date: Wed, 11 Jan 2017 11:50:06 +1100
Subject: drivers/pci/hotplug: Handle presence detection change properly

From: Gavin Shan <[email protected]>

commit d7d55536c6cd1f80295b6d7483ad0587b148bde4 upstream.

The surprise hotplug is driven by interrupt in PowerNV PCI hotplug driver. In the interrupt handler, pnv_php_interrupt(), we bail when pnv_pci_get_presence_state() returns zero wrongly. It causes the presence change event is always ignored incorrectly.

This fixes the issue by bailing on error (non-zero value) returned from pnv_pci_get_presence_state().

---
 drivers/pci/hotplug/pnv_php.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

@@ -713,8 +713,12 @@ static irqreturn_t pnv_php_interrupt(int
 		added = !!(lsts & PCI_EXP_LNKSTA_DLLLA);
 	} else if (sts & PCI_EXP_SLTSTA_PDC) {
 		ret = pnv_pci_get_presence_state(php_slot->id, &presence);
-		if (!ret)
+		if (ret) {
+			dev_warn(&pdev->dev, "PCI slot [%s] error %d getting presence (0x%04x), to retry the operation.\n",
+				 php_slot->name, ret, sts);
 			return IRQ_HANDLED;
+		}
+
 		added = !!(presence == OPAL_PCI_SLOT_PRESENT);
 	} else {
 		return IRQ_NONE;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/pci-hotplug-pnv-php-remove-warn_on-in-pnv_php_put_slot.patch queue-4.9/pci-hotplug-pnv-php-disable-surprise-hotplug-capability-on-conflicts.patch queue-4.9/drivers-pci-hotplug-handle-presence-detection-change-properly.patch queue-4.9/drivers-pci-hotplug-fix-initial-state-for-empty-slot.patch