drivers/pci/hotplug: Handle presence detection change properly

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@vger.kernel.org #v4.9+
Reported-by: Hank Chang <hankmax0000@gmail.com>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Tested-by: Willie Liauw <williel@supermicro.com.tw>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
index 56efaf72d08e589bbaa13b15513534b144c1b174..306728cb57857a0e12ec70cb88b52a8220537faf 100644 (file)
--- 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 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;