linux-kernel - [PATCH 5/5] PCI/xen-pcifront: simplify code by hotplug safe pci_get_domain_bus_and

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Date:	Tue, 28 Aug 2012 23:43:58 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	Jiang Liu <jiang.liu@...wei.com>, Don Dutile <ddutile@...hat.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Yijing Wang <wangyijing@...wei.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: [PATCH 5/5] PCI/xen-pcifront: simplify code by hotplug safe pci_get_domain_bus_and_slot()

Following code has a race window between pci_find_bus() and pci_get_slot()
if PCI hotplug operation happens between them which removes the pci_bus.
So use PCI hotplug safe interface pci_get_domain_bus_and_slot() instead,
which also reduces code complexity.

struct pci_bus *pci_bus = pci_find_bus(domain, busno);
struct pci_dev *pci_dev = pci_get_slot(pci_bus, devfn);

Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
---
 drivers/pci/xen-pcifront.c |   10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index d6cc62c..def8d0b 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -982,7 +982,6 @@ static int pcifront_detach_devices(struct pcifront_device *pdev)
 	int err = 0;
 	int i, num_devs;
 	unsigned int domain, bus, slot, func;
-	struct pci_bus *pci_bus;
 	struct pci_dev *pci_dev;
 	char str[64];
 
@@ -1032,13 +1031,8 @@ static int pcifront_detach_devices(struct pcifront_device *pdev)
 			goto out;
 		}
 
-		pci_bus = pci_find_bus(domain, bus);
-		if (!pci_bus) {
-			dev_dbg(&pdev->xdev->dev, "Cannot get bus %04x:%02x\n",
-				domain, bus);
-			continue;
-		}
-		pci_dev = pci_get_slot(pci_bus, PCI_DEVFN(slot, func));
+		pci_dev = pci_get_domain_bus_and_slot(domain, bus,
+				PCI_DEVFN(slot, func));
 		if (!pci_dev) {
 			dev_dbg(&pdev->xdev->dev,
 				"Cannot get PCI device %04x:%02x:%02x.%d\n",
-- 
1.7.9.5

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