[PATCH] drivers/pci/hotplug: Handle presence detection change properly

[Gavin Shan]

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().

Fixes: 360aebd85a4 ("drivers/pci/hotplug: Support surprise hotplug in powernv driver")
Cc: stable at vger.kernel.org #v4.9+
Reported-by: Hank Chang <hankmax0000 at gmail.com>
Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
Tested-by: Willie Liauw <williel at supermicro.com.tw>
---
 drivers/pci/hotplug/pnv_php.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
index 56efaf7..38a2309 100644
--- a/drivers/pci/hotplug/pnv_php.c
+++ b/drivers/pci/hotplug/pnv_php.c
@@ -707,8 +707,12 @@ static irqreturn_t pnv_php_interrupt(int irq, void *data)
 		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 handling PDC event (0x%04x)\n",
+				php_slot->name, ret, sts);
 			return IRQ_HANDLED;
+		}
+
 		added = !!(presence == OPAL_PCI_SLOT_PRESENT);
 	} else {
 		return IRQ_NONE;
-- 
2.7.4