linux-kernel - [RFC PATCH v1 10/22] PCI: enhance PCI bus specific logic to support PCI bus lock mechanism

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Date:	Wed,  8 Aug 2012 00:10:50 +0800
From:	Jiang Liu <liuj97@...il.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Don Dutile <ddutile@...hat.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Cc:	Jiang Liu <jiang.liu@...wei.com>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	"Rafael J . Wysocki" <rjw@...k.pl>,
	Yijing Wang <wangyijing@...wei.com>,
	Xinwei Hu <huxinwei@...wei.com>, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, Jiang Liu <liuj97@...il.com>
Subject: [RFC PATCH v1 10/22] PCI: enhance PCI bus specific logic to support PCI bus lock mechanism

This patch enhances PCI bus specific logic to support PCI bus lock mechanism.

Signed-off-by: Jiang Liu <liuj97@...il.com>
---
 drivers/pci/bus.c |   54 ++++++++++++++++++++++++++++++-----------------------
 1 file changed, 31 insertions(+), 23 deletions(-)

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index b6aacaa..371f20a 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -185,19 +185,20 @@ int pci_bus_add_device(struct pci_dev *dev)
  */
 int pci_bus_add_child(struct pci_bus *bus)
 {
-	int retval;
-
-	if (bus->bridge)
-		bus->dev.parent = bus->bridge;
-
-	retval = device_add(&bus->dev);
-	if (retval)
-		return retval;
-
-	bus->is_added = 1;
-
-	/* Create legacy_io and legacy_mem files for this bus */
-	pci_create_legacy_files(bus);
+	int retval = -EBUSY;
+
+	if (pci_bus_get_state(bus) == PCI_BUS_STATE_INITIALIZED) {
+		if (bus->bridge)
+			bus->dev.parent = bus->bridge;
+		retval = device_add(&bus->dev);
+		if (retval == 0) {
+			/* Create legacy_io and legacy_mem files for this bus */
+			pci_create_legacy_files(bus);
+			pci_bus_change_state(bus, PCI_BUS_STATE_INITIALIZED,
+					PCI_BUS_STATE_WORKING, false);
+			bus->is_added = 1;
+		}
+	}
 
 	return retval;
 }
@@ -232,13 +233,14 @@ void pci_bus_add_devices(const struct pci_bus *bus)
 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		BUG_ON(!dev->is_added);
 
-		child = dev->subordinate;
+		child = pci_lock_subordinate(dev, PCI_BUS_STATE_STOPPING - 1);
+		if (!child)
+			continue;
+
 		/*
 		 * If there is an unattached subordinate bus, attach
 		 * it and then scan for unattached PCI devices.
 		 */
-		if (!child)
-			continue;
 		if (list_empty(&child->node)) {
 			down_write(&pci_bus_sem);
 			list_add_tail(&child->node, &dev->bus->children);
@@ -250,28 +252,34 @@ void pci_bus_add_devices(const struct pci_bus *bus)
 		 * register the bus with sysfs as the parent is now
 		 * properly registered.
 		 */
-		if (child->is_added)
-			continue;
-		retval = pci_bus_add_child(child);
-		if (retval)
-			dev_err(&dev->dev, "Error adding bus, continuing\n");
+		if (pci_bus_get_state(child) == PCI_BUS_STATE_INITIALIZED) {
+			retval = pci_bus_add_child(child);
+			if (retval)
+				dev_err(&dev->dev,
+					"Error adding bus, continuing\n");
+		}
+
+		pci_bus_unlock(child);
 	}
 }
 
 void pci_enable_bridges(struct pci_bus *bus)
 {
 	struct pci_dev *dev;
+	struct pci_bus *child;
 	int retval;
 
 	list_for_each_entry(dev, &bus->devices, bus_list) {
-		if (dev->subordinate) {
+		child = pci_lock_subordinate(dev, PCI_BUS_STATE_STOPPING - 1);
+		if (child) {
 			if (!pci_is_enabled(dev)) {
 				retval = pci_enable_device(dev);
 				if (retval)
 					dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n", retval);
 				pci_set_master(dev);
 			}
-			pci_enable_bridges(dev->subordinate);
+			pci_enable_bridges(child);
+			pci_bus_unlock(child);
 		}
 	}
 }
-- 
1.7.9.5

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