linux-kernel - [PATCH v9 04/16] PCI/acpiphp: don't rely on function 0 in disable

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Date:	Fri, 12 Apr 2013 23:44:18 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	"Rafael J . Wysocki" <rjw@...k.pl>
Cc:	Jiang Liu <jiang.liu@...wei.com>, Yinghai Lu <yinghai@...nel.org>,
	Yijing Wang <wangyijing@...wei.com>,
	Jiang Liu <liuj97@...il.com>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Toshi Kani <toshi.kani@...com>,
	Myron Stowe <myron.stowe@...hat.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH v9 04/16] PCI/acpiphp: don't rely on function 0 in disable_device()

Currently function disable_device() detects slot state by checking
existence of PCI device for function 0. It's unreliable because PCI
device for function 0 may be removed through sysfs interface. If that
happens, it will cause powering off a hotplug slot without destroying
all PCI devices.

On the other hand, it won't hurt us except wasting some computation
power if the check is removed, because all code of disable_device()
is self-protected. So remove the check.

Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
Signed-off-by: Yijing Wang <wangyijing@...wei.com>
Cc: Yinghai Lu <yinghai@...nel.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Cc: Toshi Kani <toshi.kani@...com>
Cc: linux-pci@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
 drivers/pci/hotplug/acpiphp_glue.c |    7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 7948bc9..a1c8dd6 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -914,13 +914,6 @@ static int disable_device(struct acpiphp_slot *slot)
 	struct pci_dev *pdev;
 	struct pci_bus *bus = slot->bridge->pci_bus;
 
-	/* The slot will be enabled when func 0 is added, so check
-	   func 0 before disable the slot. */
-	pdev = pci_get_slot(bus, PCI_DEVFN(slot->device, 0));
-	if (!pdev)
-		goto err_exit;
-	pci_dev_put(pdev);
-
 	list_for_each_entry(func, &slot->funcs, sibling) {
 		if (func->bridge) {
 			/* cleanup p2p bridges under this P2P bridge */
-- 
1.7.9.5

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