From: Gavin Shan <gwshan@linux.vnet.ibm.com>
Date: Wed, 11 Jan 2017 00:50:06 +0000 (+1100)
Subject: drivers/pci/hotplug: Handle presence detection change properly
X-Git-Tag: Ubuntu-4.10.0-19.21~492
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=633992b3d9078224e395d67ed429f575d7a94aec;p=mirror_ubuntu-artful-kernel.git

drivers/pci/hotplug: Handle presence detection change properly

BugLink: http://bugs.launchpad.net/bugs/1673118

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().

Fixes: 360aebd85a4 ("drivers/pci/hotplug: Support surprise hotplug in powernv driver")
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---

diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
index 99b05338b4bc..e1c29909e7d3 100644
--- a/drivers/pci/hotplug/pnv_php.c
+++ b/drivers/pci/hotplug/pnv_php.c
@@ -713,8 +713,12 @@ 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;