[RFC PATCH v2, part 2 01/18] PCI: introduce hotplug-safe PCI bus iterators

[RFC PATCH v2, part 2 01/18] PCI: introduce hotplug-safe PCI bus iterators

[Jiang Liu]

Introduce hotplug-safe PCI bus iterators as below, which hold a
reference on the returned PCI bus object.
bool pci_bus_exists(int domain, int busnr);
struct pci_bus *pci_get_bus(int domain, int busnr);
struct pci_bus *pci_get_next_bus(struct pci_bus *from);
struct pci_bus *pci_get_next_root_bus(struct pci_bus *from);
#define for_each_pci_bus(b) for (b = NULL; (b = pci_get_next_bus(b)); )
#define for_each_pci_root_bus(b)  \
		for (b = NULL; (b = pci_get_next_root_bus(b)); )

The long-term goal is to remove hotplug-unsafe pci_find_bus(),
pci_find_next_bus() and the global pci_root_buses list.

These new interfaces may be a littler slower than existing interfaces,
but it should be acceptable because they are not used on hot paths.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: linux-pci@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/pci/pci.h    |   1 +
 drivers/pci/probe.c  |   2 +-
 drivers/pci/search.c | 159 +++++++++++++++++++++++++++++++++++++++++----------
 include/linux/pci.h  |  23 +++++++-
 4 files changed, 153 insertions(+), 32 deletions(-)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 68678ed..8fe15f6 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -126,6 +126,7 @@ static inline void pci_remove_legacy_files(struct pci_bus *bus) { return; }
 
 /* Lock for read/write access to pci device and bus lists */
 extern struct rw_semaphore pci_bus_sem;
+extern struct class pcibus_class;
 
 extern raw_spinlock_t pci_lock;
 
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index e59433a..6b77333 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -93,7 +93,7 @@ static void release_pcibus_dev(struct device *dev)
 	kfree(pci_bus);
 }
 
-static struct class pcibus_class = {
+struct class pcibus_class = {
 	.name		= "pci_bus",
 	.dev_release	= &release_pcibus_dev,
 	.dev_attrs	= pcibus_dev_attrs,
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index d0627fa..16ccaf8 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -52,20 +52,27 @@ pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
 	return tmp;
 }
 
-static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr)
+struct pci_bus_match_arg {
+	int domain;
+	int bus;
+};
+
+static int pci_match_bus(struct device *dev, const void *data)
 {
-	struct pci_bus* child;
-	struct list_head *tmp;
+	struct pci_bus *bus = to_pci_bus(dev);
+	const struct pci_bus_match_arg *arg = data;
 
-	if(bus->number == busnr)
-		return bus;
+	return (pci_domain_nr(bus) == arg->domain && bus->number == arg->bus);
+}
 
-	list_for_each(tmp, &bus->children) {
-		child = pci_do_find_bus(pci_bus_b(tmp), busnr);
-		if(child)
-			return child;
-	}
-	return NULL;
+static int pci_match_next_bus(struct device *dev, const void *data)
+{
+	return 1;
+}
+
+static int pci_match_next_root_bus(struct device *dev, const void *data)
+{
+	return pci_is_root_bus(to_pci_bus(dev));
 }
 
 /**
@@ -76,20 +83,19 @@ static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr)
  * Given a PCI bus number and domain number, the desired PCI bus is located
  * in the global list of PCI buses.  If the bus is found, a pointer to its
  * data structure is returned.  If no bus is found, %NULL is returned.
+ *
+ * Note: it's not hotplug safe, the returned bus may be destroyed at any time.
+ * Please use pci_get_bus() instead which holds a reference on the returned
+ * PCI bus.
  */
-struct pci_bus * pci_find_bus(int domain, int busnr)
+struct pci_bus *pci_find_bus(int domain, int busnr)
 {
-	struct pci_bus *bus = NULL;
-	struct pci_bus *tmp_bus;
+	struct pci_bus *bus;
 
-	while ((bus = pci_find_next_bus(bus)) != NULL)  {
-		if (pci_domain_nr(bus) != domain)
-			continue;
-		tmp_bus = pci_do_find_bus(bus, busnr);
-		if (tmp_bus)
-			return tmp_bus;
-	}
-	return NULL;
+	bus = pci_get_bus(domain, busnr);
+	pci_bus_put(bus);
+
+	return bus;
 }
 
 /**
@@ -100,21 +106,114 @@ struct pci_bus * pci_find_bus(int domain, int busnr)
  * initiated by passing %NULL as the @from argument.  Otherwise if
  * @from is not %NULL, searches continue from next device on the
  * global list.
+ *
+ * Note: it's not hotplug safe, the returned bus may be destroyed at any time.
+ * Please use pci_get_next_root_bus() instead which holds a reference
+ * on the returned PCI root bus.
  */
 struct pci_bus * 
 pci_find_next_bus(const struct pci_bus *from)
 {
-	struct list_head *n;
-	struct pci_bus *b = NULL;
+	struct device *dev = from ? (struct device *)&from->dev : NULL;
+
+	dev = class_find_device(&pcibus_class, dev, NULL,
+				&pci_match_next_root_bus);
+	if (dev) {
+		put_device(dev);
+		return to_pci_bus(dev);
+	}
+
+	return NULL;
+}
+
+bool pci_bus_exists(int domain, int busnr)
+{
+	struct device *dev;
+	struct pci_bus_match_arg arg = { domain, busnr };
 
 	WARN_ON(in_interrupt());
-	down_read(&pci_bus_sem);
-	n = from ? from->node.next : pci_root_buses.next;
-	if (n != &pci_root_buses)
-		b = pci_bus_b(n);
-	up_read(&pci_bus_sem);
-	return b;
+	dev = class_find_device(&pcibus_class, NULL, &arg, &pci_match_bus);
+	if (dev)
+		put_device(dev);
+
+	return dev != NULL;
+}
+EXPORT_SYMBOL(pci_bus_exists);
+
+/**
+ * pci_get_bus - locate PCI bus from a given domain and bus number
+ * @domain: number of PCI domain to search
+ * @busnr: number of desired PCI bus
+ *
+ * Given a PCI bus number and domain number, the desired PCI bus is located.
+ * If the bus is found, a pointer to its data structure is returned.
+ * If no bus is found, %NULL is returned.
+ * Caller needs to release the returned bus by calling pci_bus_put().
+ */
+struct pci_bus *pci_get_bus(int domain, int busnr)
+{
+	struct device *dev;
+	struct pci_bus_match_arg arg = { domain, busnr };
+
+	WARN_ON(in_interrupt());
+	dev = class_find_device(&pcibus_class, NULL, &arg, &pci_match_bus);
+	if (dev)
+		return to_pci_bus(dev);
+
+	return NULL;
+}
+EXPORT_SYMBOL(pci_get_bus);
+
+/**
+ * pci_get_next_bus - begin or continue searching for a PCI bus
+ * @from: Previous PCI bus found, or %NULL for new search.
+ *
+ * Iterates through the list of known PCI busses. If a PCI bus is found,
+ * the reference count to the bus is incremented and a pointer to it is
+ * returned. Otherwise, %NULL is returned. A new search is initiated by
+ * passing %NULL as the @from argument. Otherwise if @from is not %NULL,
+ * searches continue from next bus on the global list. The reference count
+ * for @from is always decremented if it is not %NULL.
+ */
+struct pci_bus *pci_get_next_bus(struct pci_bus *from)
+{
+	struct device *dev = from ? &from->dev : NULL;
+
+	WARN_ON(in_interrupt());
+	dev = class_find_device(&pcibus_class, dev, NULL, &pci_match_next_bus);
+	pci_bus_put(from);
+	if (dev)
+		return to_pci_bus(dev);
+
+	return NULL;
+}
+EXPORT_SYMBOL(pci_get_next_bus);
+
+/**
+ * pci_find_next_root_bus - begin or continue searching for a PCI root bus
+ * @from: Previous PCI bus found, or %NULL for new search.
+ *
+ * Iterates through the list of known PCI root busses. If a PCI bus is found,
+ * the reference count to the root bus is incremented and a pointer to it is
+ * returned. Otherwise, %NULL is returned. A new search is initiated by
+ * passing %NULL as the @from argument. Otherwise if @from is not %NULL,
+ * searches continue from next root bus on the global list. The reference
+ * count for @from is always decremented if it is not %NULL.
+ */
+struct pci_bus *pci_get_next_root_bus(struct pci_bus *from)
+{
+	struct device *dev = from ? &from->dev : NULL;
+
+	WARN_ON(in_interrupt());
+	dev = class_find_device(&pcibus_class, dev, NULL,
+				&pci_match_next_root_bus);
+	pci_bus_put(from);
+	if (dev)
+		return to_pci_bus(dev);
+
+	return NULL;
 }
+EXPORT_SYMBOL(pci_get_next_root_bus);
 
 /**
  * pci_get_slot - locate PCI device for a given PCI slot
diff --git a/include/linux/pci.h b/include/linux/pci.h
index cc4ce27..c88d4e6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -454,6 +454,9 @@ struct pci_bus {
 
 #define pci_bus_b(n)	list_entry(n, struct pci_bus, node)
 #define to_pci_bus(n)	container_of(n, struct pci_bus, dev)
+#define for_each_pci_bus(b)	for (b = NULL; (b = pci_get_next_bus(b)); )
+#define for_each_pci_root_bus(b) \
+			for (b = NULL; (b = pci_get_next_root_bus(b)); )
 
 /*
  * Returns true if the pci bus is root (behind host-pci bridge),
@@ -718,7 +721,6 @@ void pcibios_resource_to_bus(struct pci_dev *dev, struct pci_bus_region *region,
 void pcibios_bus_to_resource(struct pci_dev *dev, struct resource *res,
 			     struct pci_bus_region *region);
 void pcibios_scan_specific_bus(int busn);
-struct pci_bus *pci_find_bus(int domain, int busnr);
 void pci_bus_add_devices(const struct pci_bus *bus);
 struct pci_bus * __deprecated pci_scan_bus_parented(struct device *parent,
 			int bus, struct pci_ops *ops, void *sysdata);
@@ -778,8 +780,15 @@ int pci_find_ext_capability(struct pci_dev *dev, int cap);
 int pci_find_next_ext_capability(struct pci_dev *dev, int pos, int cap);
 int pci_find_ht_capability(struct pci_dev *dev, int ht_cap);
 int pci_find_next_ht_capability(struct pci_dev *dev, int pos, int ht_cap);
+
+struct pci_bus *pci_find_bus(int domain, int busnr);
 struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
 
+bool pci_bus_exists(int domain, int busnr);
+struct pci_bus *pci_get_bus(int domain, int busnr);
+struct pci_bus *pci_get_next_bus(struct pci_bus *from);
+struct pci_bus *pci_get_next_root_bus(struct pci_bus *from);
+
 struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
 				struct pci_dev *from);
 struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
@@ -1429,6 +1438,18 @@ static inline void pci_unblock_cfg_access(struct pci_dev *dev)
 static inline struct pci_bus *pci_find_next_bus(const struct pci_bus *from)
 { return NULL; }
 
+static inline bool pci_bus_exists(int domain, int busnr)
+{ return false; }
+
+static inline struct pci_bus *pci_get_bus(int domain, int busnr)
+{ return NULL; }
+
+static inline struct pci_bus *pci_get_next_bus(struct pci_bus *from)
+{ return NULL; }
+
+static inline struct pci_bus *pci_get_next_root_bus(struct pci_bus *from)
+{ return NULL; }
+
 static inline struct pci_dev *pci_get_slot(struct pci_bus *bus,
 						unsigned int devfn)
 { return NULL; }
-- 
1.8.1.2

[RFC PATCH v2, part 2 02/18] PCI, core: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance PCI core to use hotplug-safe iterators to walk PCI buses.

In other words, replace pci_find_bus(), pci_find_next_bus() and
pci_root_buses with pci_bus_exists(), pci_get_bus(), pci_get_next_bus()
and pci_get_next_root_bus() etc.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: linux-pci@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: xen-devel@lists.xensource.com
Cc: virtualization@lists.linux-foundation.org
---
 drivers/pci/pci-sysfs.c    |  2 +-
 drivers/pci/pcie/pme.c     |  5 +++--
 drivers/pci/probe.c        | 15 +++++++++------
 drivers/pci/setup-bus.c    | 14 ++++++--------
 drivers/pci/xen-pcifront.c |  3 ++-
 5 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 5b4a9d9..fcc4bb2 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -296,7 +296,7 @@ static ssize_t bus_rescan_store(struct bus_type *bus, const char *buf,
 
 	if (val) {
 		mutex_lock(&pci_remove_rescan_mutex);
-		while ((b = pci_find_next_bus(b)) != NULL)
+		for_each_pci_root_bus(b)
 			pci_rescan_bus(b);
 		mutex_unlock(&pci_remove_rescan_mutex);
 	}
diff --git a/drivers/pci/pcie/pme.c b/drivers/pci/pcie/pme.c
index 795db1f..1ed38a3 100644
--- a/drivers/pci/pcie/pme.c
+++ b/drivers/pci/pcie/pme.c
@@ -132,7 +132,7 @@ static bool pcie_pme_from_pci_bridge(struct pci_bus *bus, u8 devfn)
 static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
 {
 	u8 busnr = req_id >> 8, devfn = req_id & 0xff;
-	struct pci_bus *bus;
+	struct pci_bus *bus = NULL;
 	struct pci_dev *dev;
 	bool found = false;
 
@@ -161,7 +161,7 @@ static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
 	}
 
 	/* Second, find the bus the source device is on. */
-	bus = pci_find_bus(pci_domain_nr(port->bus), busnr);
+	bus = pci_get_bus(pci_domain_nr(port->bus), busnr);
 	if (!bus)
 		goto out;
 
@@ -206,6 +206,7 @@ static void pcie_pme_handle_request(struct pci_dev *port, u16 req_id)
 	}
 
  out:
+	pci_bus_put(bus);
 	if (!found)
 		dev_dbg(&port->dev, "Spurious native PME interrupt!\n");
 }
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 6b77333..cc5e432 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -733,7 +733,7 @@ static void pci_fixup_parent_subordinate_busnr(struct pci_bus *child, int max)
  */
 int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 {
-	struct pci_bus *child;
+	struct pci_bus *child = NULL;
 	int is_cardbus = (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS);
 	u32 buses, i, j = 0;
 	u16 bctl;
@@ -785,7 +785,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 		 * However, we continue to descend down the hierarchy and
 		 * scan remaining child buses.
 		 */
-		child = pci_find_bus(pci_domain_nr(bus), secondary);
+		child = pci_get_bus(pci_domain_nr(bus), secondary);
 		if (!child) {
 			child = pci_add_new_bus(bus, dev, secondary);
 			if (!child)
@@ -793,6 +793,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 			child->primary = primary;
 			pci_bus_insert_busn_res(child, secondary, subordinate);
 			child->bridge_ctl = bctl;
+			pci_bus_get(child);
 		}
 
 		cmax = pci_scan_child_bus(child);
@@ -824,12 +825,13 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 		/* Prevent assigning a bus number that already exists.
 		 * This can happen when a bridge is hot-plugged, so in
 		 * this case we only re-scan this bus. */
-		child = pci_find_bus(pci_domain_nr(bus), max+1);
+		child = pci_get_bus(pci_domain_nr(bus), max+1);
 		if (!child) {
 			child = pci_add_new_bus(bus, dev, ++max);
 			if (!child)
 				goto out;
 			pci_bus_insert_busn_res(child, max, 0xff);
+			pci_bus_get(child);
 		}
 		buses = (buses & 0xff000000)
 		      | ((unsigned int)(child->primary)     <<  0)
@@ -874,8 +876,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 			 */
 			for (i=0; i<CARDBUS_RESERVE_BUSNR; i++) {
 				struct pci_bus *parent = bus;
-				if (pci_find_bus(pci_domain_nr(bus),
-							max+i+1))
+				if (pci_bus_exists(pci_domain_nr(bus), max+i+1))
 					break;
 				while (parent->parent) {
 					if ((!pcibios_assign_all_busses()) &&
@@ -930,6 +931,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
 
 out:
 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);
+	pci_bus_put(child);
 
 	return max;
 }
@@ -1691,10 +1693,11 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 	if (!b)
 		return NULL;
 
-	b2 = pci_find_bus(pci_domain_nr(b), bus);
+	b2 = pci_get_bus(pci_domain_nr(b), bus);
 	if (b2) {
 		/* If we already got to this bus through a different bridge, ignore it */
 		dev_dbg(&b2->dev, "bus already known\n");
+		pci_bus_put(b2);
 		goto err_out;
 	}
 
diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 16abaaa..9a3e3f7 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1317,12 +1317,10 @@ static int __init pci_bus_get_depth(struct pci_bus *bus)
 }
 static int __init pci_get_max_depth(void)
 {
-	int depth = 0;
+	int ret, depth = 0;
 	struct pci_bus *bus;
 
-	list_for_each_entry(bus, &pci_root_buses, node) {
-		int ret;
-
+	for_each_pci_root_bus(bus) {
 		ret = pci_bus_get_depth(bus);
 		if (ret > depth)
 			depth = ret;
@@ -1423,11 +1421,11 @@ again:
 		add_list = &realloc_head;
 	/* Depth first, calculate sizes and alignments of all
 	   subordinate buses. */
-	list_for_each_entry(bus, &pci_root_buses, node)
+	for_each_pci_root_bus(bus)
 		__pci_bus_size_bridges(bus, add_list);
 
 	/* Depth last, allocate resources and update the hardware. */
-	list_for_each_entry(bus, &pci_root_buses, node)
+	for_each_pci_root_bus(bus)
 		__pci_bus_assign_resources(bus, add_list, &fail_head);
 	if (add_list)
 		BUG_ON(!list_empty(add_list));
@@ -1480,11 +1478,11 @@ again:
 
 enable_and_dump:
 	/* Depth last, update the hardware. */
-	list_for_each_entry(bus, &pci_root_buses, node)
+	for_each_pci_root_bus(bus)
 		pci_enable_bridges(bus);
 
 	/* dump the resource on buses */
-	list_for_each_entry(bus, &pci_root_buses, node)
+	for_each_pci_root_bus(bus)
 		pci_bus_dump_resources(bus);
 }
 
diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 966abc6..816cf94 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -522,7 +522,7 @@ static int pcifront_rescan_root(struct pcifront_device *pdev,
 	dev_info(&pdev->xdev->dev, "Rescanning PCI Frontend Bus %04x:%02x\n",
 		 domain, bus);
 
-	b = pci_find_bus(domain, bus);
+	b = pci_get_bus(domain, bus);
 	if (!b)
 		/* If the bus is unknown, create it. */
 		return pcifront_scan_root(pdev, domain, bus);
@@ -534,6 +534,7 @@ static int pcifront_rescan_root(struct pcifront_device *pdev,
 
 	/* Create SysFS and notify udev of the devices. Aka: "going live" */
 	pci_bus_add_devices(b);
+	pci_bus_put(b);
 
 	return err;
 }
-- 
1.8.1.2

[RFC PATCH v2, part 2 03/18] PCI, hotplug: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance PCI hotplug drivers to use hotplug-safe iterators to walk
PCI buses.

In other words, replace pci_find_bus(), pci_find_next_bus() and
pci_root_buses with pci_bus_exists(), pci_get_bus(), pci_get_next_bus()
and pci_get_next_root_bus() etc.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Masanari Iida <standby24x7@gmail.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: linux-pci@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/pci/hotplug-pci.c          | 2 +-
 drivers/pci/hotplug/ibmphp_core.c  | 8 +++++---
 drivers/pci/hotplug/ibmphp_ebda.c  | 8 ++++++--
 drivers/pci/hotplug/sgi_hotplug.c  | 3 ++-
 drivers/pci/hotplug/shpchp_sysfs.c | 2 +-
 5 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/hotplug-pci.c b/drivers/pci/hotplug-pci.c
index 6258dc2..18533ed 100644
--- a/drivers/pci/hotplug-pci.c
+++ b/drivers/pci/hotplug-pci.c
@@ -11,7 +11,7 @@ int __ref pci_hp_add_bridge(struct pci_dev *dev)
 	int end = parent->busn_res.end;
 
 	for (busnr = start; busnr <= end; busnr++) {
-		if (!pci_find_bus(pci_domain_nr(parent), busnr))
+		if (!pci_bus_exists(pci_domain_nr(parent), busnr))
 			break;
 	}
 	if (busnr-- > end) {
diff --git a/drivers/pci/hotplug/ibmphp_core.c b/drivers/pci/hotplug/ibmphp_core.c
index cbd72d8..fb47695 100644
--- a/drivers/pci/hotplug/ibmphp_core.c
+++ b/drivers/pci/hotplug/ibmphp_core.c
@@ -739,7 +739,7 @@ static u8 bus_structure_fixup(u8 busno)
 	struct pci_dev *dev;
 	u16 l;
 
-	if (pci_find_bus(0, busno) || !(ibmphp_find_same_bus_num(busno)))
+	if (pci_bus_exists(0, busno) || !(ibmphp_find_same_bus_num(busno)))
 		return 1;
 
 	bus = kmalloc(sizeof(*bus), GFP_KERNEL);
@@ -787,7 +787,7 @@ static int ibm_configure_device(struct pci_func *func)
 				PCI_DEVFN(func->device, func->function));
 
 	if (func->dev == NULL) {
-		struct pci_bus *bus = pci_find_bus(0, func->busno);
+		struct pci_bus *bus = pci_get_bus(0, func->busno);
 		if (!bus)
 			return 0;
 
@@ -795,6 +795,7 @@ static int ibm_configure_device(struct pci_func *func)
 				PCI_DEVFN(func->device, func->function));
 		if (num)
 			pci_bus_add_devices(bus);
+		pci_bus_put(bus);
 
 		func->dev = pci_get_bus_and_slot(func->busno,
 				PCI_DEVFN(func->device, func->function));
@@ -1315,13 +1316,14 @@ static int __init ibmphp_init(void)
 		goto exit;
 	}
 
-	bus = pci_find_bus(0, 0);
+	bus = pci_get_bus(0, 0);
 	if (!bus) {
 		err("Can't find the root pci bus, can not continue\n");
 		rc = -ENODEV;
 		goto error;
 	}
 	memcpy(ibmphp_pci_bus, bus, sizeof(*ibmphp_pci_bus));
+	pci_bus_put(bus);
 
 	ibmphp_debug = debug;
 
diff --git a/drivers/pci/hotplug/ibmphp_ebda.c b/drivers/pci/hotplug/ibmphp_ebda.c
index 9df78bc..e17f271 100644
--- a/drivers/pci/hotplug/ibmphp_ebda.c
+++ b/drivers/pci/hotplug/ibmphp_ebda.c
@@ -978,9 +978,13 @@ static int __init ebda_rsrc_controller (void)
 	}			/* each hpc  */
 
 	list_for_each_entry(tmp_slot, &ibmphp_slot_head, ibm_slot_list) {
+		struct pci_bus *bus = pci_get_bus(0, tmp_slot->bus);
+
+		BUG_ON(!bus);
 		snprintf(name, SLOT_NAME_SIZE, "%s", create_file_name(tmp_slot));
-		pci_hp_register(tmp_slot->hotplug_slot,
-			pci_find_bus(0, tmp_slot->bus), tmp_slot->device, name);
+		pci_hp_register(tmp_slot->hotplug_slot, bus, tmp_slot->device,
+				name);
+		pci_bus_put(bus);
 	}
 
 	print_ebda_hpc ();
diff --git a/drivers/pci/hotplug/sgi_hotplug.c b/drivers/pci/hotplug/sgi_hotplug.c
index b2781df..5c69bda 100644
--- a/drivers/pci/hotplug/sgi_hotplug.c
+++ b/drivers/pci/hotplug/sgi_hotplug.c
@@ -684,7 +684,7 @@ static int __init sn_pci_hotplug_init(void)
 
 	INIT_LIST_HEAD(&sn_hp_list);
 
-	while ((pci_bus = pci_find_next_bus(pci_bus))) {
+	for_each_pci_root_bus(pci_bus) {
 		if (!pci_bus->sysdata)
 			continue;
 
@@ -703,6 +703,7 @@ static int __init sn_pci_hotplug_init(void)
 			break;
 		}
 	}
+	pci_bus_put(pci_bus);
 
 	return registered == 1 ? 0 : -ENODEV;
 }
diff --git a/drivers/pci/hotplug/shpchp_sysfs.c b/drivers/pci/hotplug/shpchp_sysfs.c
index e8c31fe..e7a5dd2 100644
--- a/drivers/pci/hotplug/shpchp_sysfs.c
+++ b/drivers/pci/hotplug/shpchp_sysfs.c
@@ -74,7 +74,7 @@ static ssize_t show_ctrl (struct device *dev, struct device_attribute *attr, cha
 	}
 	out += sprintf(out, "Free resources: bus numbers\n");
 	for (busnr = bus->busn_res.start; busnr <= bus->busn_res.end; busnr++) {
-		if (!pci_find_bus(pci_domain_nr(bus), busnr))
+		if (!pci_bus_exists(pci_domain_nr(bus), busnr))
 			break;
 	}
 	if (busnr < bus->busn_res.end)
-- 
1.8.1.2

[RFC PATCH v2, part 2 04/18] PCI, Alpha: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance Alpha architecture specific code to use hotplug-safe iterators
to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
 arch/alpha/kernel/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/alpha/kernel/pci.c b/arch/alpha/kernel/pci.c
index edb4e00..094cd58 100644
--- a/arch/alpha/kernel/pci.c
+++ b/arch/alpha/kernel/pci.c
@@ -305,7 +305,7 @@ pcibios_claim_console_setup(void)
 {
 	struct pci_bus *b;
 
-	list_for_each_entry(b, &pci_root_buses, node)
+	for_each_pci_root_bus(b)
 		pcibios_claim_one_bus(b);
 }
 
-- 
1.8.1.2

[RFC PATCH v2, part 2 05/18] PCI, FRV: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance FRV architecture specific code to use hotplug-safe iterators
to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linux-kernel@vger.kernel.org
---
 arch/frv/mb93090-mb00/pci-frv.c | 5 ++++-
 arch/frv/mb93090-mb00/pci-vdk.c | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/frv/mb93090-mb00/pci-frv.c b/arch/frv/mb93090-mb00/pci-frv.c
index c281217..48ee89a 100644
--- a/arch/frv/mb93090-mb00/pci-frv.c
+++ b/arch/frv/mb93090-mb00/pci-frv.c
@@ -188,8 +188,11 @@ static void __init pcibios_assign_resources(void)
 
 void __init pcibios_resource_survey(void)
 {
+	struct pci_bus *bus;
+
 	DBG("PCI: Allocating resources\n");
-	pcibios_allocate_bus_resources(&pci_root_buses);
+	for_each_pci_root_bus(bus)
+		pcibios_allocate_bus_resources(&bus->children);
 	pcibios_allocate_resources(0);
 	pcibios_allocate_resources(1);
 	pcibios_assign_resources();
diff --git a/arch/frv/mb93090-mb00/pci-vdk.c b/arch/frv/mb93090-mb00/pci-vdk.c
index 0aa35f0..f1d6c16 100644
--- a/arch/frv/mb93090-mb00/pci-vdk.c
+++ b/arch/frv/mb93090-mb00/pci-vdk.c
@@ -234,7 +234,7 @@ static void __init pcibios_fixup_peer_bridges(void)
 		return;
 	printk("PCI: Peer bridge fixup\n");
 	for (n=0; n <= pcibios_last_bus; n++) {
-		if (pci_find_bus(0, n))
+		if (pci_bus_exists(0, n))
 			continue;
 		bus.number = n;
 		bus.ops = pci_root_ops;
-- 
1.8.1.2

[RFC PATCH v2, part 2 06/18] PCI, IA64: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance IA64 architecture specific code to use hotplug-safe iterators
to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-ia64@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 arch/ia64/hp/common/sba_iommu.c   | 2 +-
 arch/ia64/sn/kernel/io_common.c   | 2 +-
 arch/ia64/sn/pci/tioca_provider.c | 3 ++-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
index bcda5b2..6faf241 100644
--- a/arch/ia64/hp/common/sba_iommu.c
+++ b/arch/ia64/hp/common/sba_iommu.c
@@ -2156,7 +2156,7 @@ sba_init(void)
 #ifdef CONFIG_PCI
 	{
 		struct pci_bus *b = NULL;
-		while ((b = pci_find_next_bus(b)) != NULL)
+		for_each_pci_root_bus(b)
 			sba_connect_bus(b);
 	}
 #endif
diff --git a/arch/ia64/sn/kernel/io_common.c b/arch/ia64/sn/kernel/io_common.c
index 11f2275..87d8d8f 100644
--- a/arch/ia64/sn/kernel/io_common.c
+++ b/arch/ia64/sn/kernel/io_common.c
@@ -530,7 +530,7 @@ sn_io_late_init(void)
 	 * info from the PROM).
 	 */
 	bus = NULL;
-	while ((bus = pci_find_next_bus(bus)) != NULL) {
+	for_each_pci_root_bus(bus) {
 		bussoft = SN_PCIBUS_BUSSOFT(bus);
 		nasid = NASID_GET(bussoft->bs_base);
 		cnode = nasid_to_cnodeid(nasid);
diff --git a/arch/ia64/sn/pci/tioca_provider.c b/arch/ia64/sn/pci/tioca_provider.c
index a70b11f..cd8c0fb 100644
--- a/arch/ia64/sn/pci/tioca_provider.c
+++ b/arch/ia64/sn/pci/tioca_provider.c
@@ -624,7 +624,7 @@ tioca_bus_fixup(struct pcibus_bussoft *prom_bussoft, struct pci_controller *cont
 	    nasid_to_cnodeid(tioca_common->ca_closest_nasid);
 	tioca_common->ca_kernel_private = (u64) tioca_kern;
 
-	bus = pci_find_bus(tioca_common->ca_common.bs_persist_segment,
+	bus = pci_get_bus(tioca_common->ca_common.bs_persist_segment,
 		tioca_common->ca_common.bs_persist_busnum);
 	BUG_ON(!bus);
 	tioca_kern->ca_devices = &bus->devices;
@@ -632,6 +632,7 @@ tioca_bus_fixup(struct pcibus_bussoft *prom_bussoft, struct pci_controller *cont
 	/* init GART */
 
 	if (tioca_gart_init(tioca_kern) < 0) {
+		pci_bus_put(bus);
 		kfree(tioca_kern);
 		kfree(tioca_common);
 		return NULL;
-- 
1.8.1.2

[RFC PATCH v2, part 2 07/18] PCI, Microblaze: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance Microblaze architecture specific code to use hotplug-safe
iterators to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Hiroo MATSUMOTO <matsumoto.hiroo@jp.fujitsu.com>
Cc: microblaze-uclinux@itee.uq.edu.au
Cc: linux-kernel@vger.kernel.org
---
 arch/microblaze/pci/pci-common.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/microblaze/pci/pci-common.c b/arch/microblaze/pci/pci-common.c
index 9ea521e..14bd8e1 100644
--- a/arch/microblaze/pci/pci-common.c
+++ b/arch/microblaze/pci/pci-common.c
@@ -1318,7 +1318,7 @@ void __init pcibios_resource_survey(void)
 	/* Allocate and assign resources. If we re-assign everything, then
 	 * we skip the allocate phase
 	 */
-	list_for_each_entry(b, &pci_root_buses, node)
+	for_each_pci_root_bus(b)
 		pcibios_allocate_bus_resources(b);
 
 	pcibios_allocate_resources(0);
@@ -1328,7 +1328,7 @@ void __init pcibios_resource_survey(void)
 	 * the low IO area and the VGA memory area if they intersect the
 	 * bus available resources to avoid allocating things on top of them
 	 */
-	list_for_each_entry(b, &pci_root_buses, node)
+	for_each_pci_root_bus(b)
 		pcibios_reserve_legacy_regions(b);
 
 	/* Now proceed to assigning things that were left unassigned */
-- 
1.8.1.2

[RFC PATCH v2, part 2 08/18] PCI, mn10300: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance mn10300 architecture specific code to use hotplug-safe
iterators to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: linux-kernel@vger.kernel.org
---
 arch/mn10300/unit-asb2305/pci-asb2305.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/mn10300/unit-asb2305/pci-asb2305.c b/arch/mn10300/unit-asb2305/pci-asb2305.c
index c4e2e79..88c0c52 100644
--- a/arch/mn10300/unit-asb2305/pci-asb2305.c
+++ b/arch/mn10300/unit-asb2305/pci-asb2305.c
@@ -207,8 +207,11 @@ fs_initcall(pcibios_assign_resources);
 
 void __init pcibios_resource_survey(void)
 {
+	struct pci_bus *bus;
+
 	DBG("PCI: Allocating resources\n");
-	pcibios_allocate_bus_resources(&pci_root_buses);
+	for_each_pci_root_bus(bus)
+		pcibios_allocate_bus_resources(&bus->children);
 	pcibios_allocate_resources(0);
 	pcibios_allocate_resources(1);
 }
-- 
1.8.1.2

[RFC PATCH v2, part 2 09/18] PCI, PPC: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance PPC architecture specific code to use hotplug-safe iterators
to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Bjorn Helgaas <bhelgaas@google.com>
Cc: Gavin Shan <shangw@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
---
 arch/powerpc/kernel/pci-common.c |  4 ++--
 arch/powerpc/kernel/pci_64.c     | 13 +++++--------
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index fa12ae4..26fca09 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -1400,7 +1400,7 @@ void __init pcibios_resource_survey(void)
 	struct pci_bus *b;
 
 	/* Allocate and assign resources */
-	list_for_each_entry(b, &pci_root_buses, node)
+	for_each_pci_root_bus(b)
 		pcibios_allocate_bus_resources(b);
 	pcibios_allocate_resources(0);
 	pcibios_allocate_resources(1);
@@ -1410,7 +1410,7 @@ void __init pcibios_resource_survey(void)
 	 * bus available resources to avoid allocating things on top of them
 	 */
 	if (!pci_has_flag(PCI_PROBE_ONLY)) {
-		list_for_each_entry(b, &pci_root_buses, node)
+		for_each_pci_root_bus(b)
 			pcibios_reserve_legacy_regions(b);
 	}
 
diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
index 51a133a..a41c6dd 100644
--- a/arch/powerpc/kernel/pci_64.c
+++ b/arch/powerpc/kernel/pci_64.c
@@ -208,7 +208,6 @@ long sys_pciconfig_iobase(long which, unsigned long in_bus,
 			  unsigned long in_devfn)
 {
 	struct pci_controller* hose;
-	struct list_head *ln;
 	struct pci_bus *bus = NULL;
 	struct device_node *hose_node;
 
@@ -229,18 +228,16 @@ long sys_pciconfig_iobase(long which, unsigned long in_bus,
 	/* That syscall isn't quite compatible with PCI domains, but it's
 	 * used on pre-domains setup. We return the first match
 	 */
-
-	for (ln = pci_root_buses.next; ln != &pci_root_buses; ln = ln->next) {
-		bus = pci_bus_b(ln);
-		if (in_bus >= bus->number && in_bus <= bus->busn_res.end)
+	for_each_pci_root_bus(bus)
+		if (in_bus >= bus->number && in_bus <= bus->busn_res.end &&
+		    bus->dev.of_node)
 			break;
-		bus = NULL;
-	}
-	if (bus == NULL || bus->dev.of_node == NULL)
+	if (bus == NULL)
 		return -ENODEV;
 
 	hose_node = bus->dev.of_node;
 	hose = PCI_DN(hose_node)->phb;
+	pci_bus_put(bus);
 
 	switch (which) {
 	case IOBASE_BRIDGE_NUMBER:
-- 
1.8.1.2

[RFC PATCH v2, part 2 10/18] PCI, SPARC: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance SPARC architecture specific code to use hotplug-safe iterators
to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: sparclinux@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 arch/sparc/kernel/pci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/sparc/kernel/pci.c b/arch/sparc/kernel/pci.c
index e5871fb..235208d8 100644
--- a/arch/sparc/kernel/pci.c
+++ b/arch/sparc/kernel/pci.c
@@ -995,9 +995,9 @@ static void pci_bus_slot_names(struct device_node *node, struct pci_bus *bus)
 
 static int __init of_pci_slot_init(void)
 {
-	struct pci_bus *pbus = NULL;
+	struct pci_bus *pbus;
 
-	while ((pbus = pci_find_next_bus(pbus)) != NULL) {
+	for_each_pci_root_bus(pbus) {
 		struct device_node *node;
 
 		if (pbus->self) {
-- 
1.8.1.2

[RFC PATCH v2, part 2 11/18] PCI, x86: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance x86 architecture specific code to use hotplug-safe iterators
to walk PCI buses.

In other words, replace pci_find_bus(), pci_find_next_bus() and
pci_root_buses with pci_bus_exists(), pci_get_bus(), pci_get_next_bus()
and pci_get_next_root_bus() etc.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Myron Stowe <myron.stowe@redhat.com>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linux-kernel@vger.kernel.org
---
 arch/x86/pci/acpi.c   | 3 ++-
 arch/x86/pci/common.c | 3 ++-
 arch/x86/pci/i386.c   | 9 ++++-----
 arch/x86/pci/irq.c    | 2 +-
 arch/x86/pci/legacy.c | 2 +-
 5 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 3e72425..b972f04 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -526,7 +526,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
 	 * Maybe the desired pci bus has been already scanned. In such case
 	 * it is unnecessary to scan the pci bus with the given domain,busnum.
 	 */
-	bus = pci_find_bus(domain, busnum);
+	bus = pci_get_bus(domain, busnum);
 	if (bus) {
 		/*
 		 * If the desired bus exits, the content of bus->sysdata will
@@ -534,6 +534,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
 		 */
 		memcpy(bus->sysdata, sd, sizeof(*sd));
 		kfree(info);
+		pci_bus_put(bus);
 	} else {
 		probe_pci_root_info(info, device, busnum, domain);
 
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 305c68b..51cc1be 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -460,8 +460,9 @@ struct pci_bus *pcibios_scan_root(int busnum)
 {
 	struct pci_bus *bus = NULL;
 
-	while ((bus = pci_find_next_bus(bus)) != NULL) {
+	for_each_pci_root_bus(bus) {
 		if (bus->number == busnum) {
+			pci_bus_put(bus);
 			/* Already scanned */
 			return bus;
 		}
diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 94919e3..6481d25 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -343,7 +343,7 @@ static int __init pcibios_assign_resources(void)
 	struct pci_bus *bus;
 
 	if (!(pci_probe & PCI_ASSIGN_ROMS))
-		list_for_each_entry(bus, &pci_root_buses, node)
+		for_each_pci_root_bus(bus)
 			pcibios_allocate_rom_resources(bus);
 
 	pci_assign_unassigned_resources();
@@ -371,12 +371,11 @@ void __init pcibios_resource_survey(void)
 
 	DBG("PCI: Allocating resources\n");
 
-	list_for_each_entry(bus, &pci_root_buses, node)
+	for_each_pci_root_bus(bus)
 		pcibios_allocate_bus_resources(bus);
-
-	list_for_each_entry(bus, &pci_root_buses, node)
+	for_each_pci_root_bus(bus)
 		pcibios_allocate_resources(bus, 0);
-	list_for_each_entry(bus, &pci_root_buses, node)
+	for_each_pci_root_bus(bus)
 		pcibios_allocate_resources(bus, 1);
 
 	e820_reserve_resources_late();
diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index 372e9b8..65898f6 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -137,7 +137,7 @@ static void __init pirq_peer_trick(void)
 	}
 	for (i = 1; i < 256; i++) {
 		int node;
-		if (!busmap[i] || pci_find_bus(0, i))
+		if (!busmap[i] || pci_bus_exists(0, i))
 			continue;
 		node = get_mp_bus_to_node(i);
 		if (pci_scan_bus_on_node(i, &pci_root_ops, node))
diff --git a/arch/x86/pci/legacy.c b/arch/x86/pci/legacy.c
index 4db96fb..1fb7922 100644
--- a/arch/x86/pci/legacy.c
+++ b/arch/x86/pci/legacy.c
@@ -40,7 +40,7 @@ void pcibios_scan_specific_bus(int busn)
 	long node;
 	u32 l;
 
-	if (pci_find_bus(0, busn))
+	if (pci_bus_exists(0, busn))
 		return;
 
 	node = get_mp_bus_to_node(busn);
-- 
1.8.1.2

[RFC PATCH v2, part 2 12/18] PCI, ACPI: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance ACPI reset drvier to use hotplug-safe iterators to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: linux-acpi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/acpi/reboot.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c
index a6c77e8b..532dd6d 100644
--- a/drivers/acpi/reboot.c
+++ b/drivers/acpi/reboot.c
@@ -33,7 +33,7 @@ void acpi_reboot(void)
 	switch (rr->space_id) {
 	case ACPI_ADR_SPACE_PCI_CONFIG:
 		/* The reset register can only live on bus 0. */
-		bus0 = pci_find_bus(0, 0);
+		bus0 = pci_get_bus(0, 0);
 		if (!bus0)
 			return;
 		/* Form PCI device/function pair. */
@@ -43,6 +43,7 @@ void acpi_reboot(void)
 		/* Write the value that resets us. */
 		pci_bus_write_config_byte(bus0, devfn,
 				(rr->address & 0xffff), reset_value);
+		pci_bus_put(bus0);
 		break;
 
 	case ACPI_ADR_SPACE_SYSTEM_MEMORY:
-- 
1.8.1.2

[RFC PATCH v2, part 2 13/18] PCI, DRM: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance DRM drvier to use hotplug-safe iterators to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/gpu/drm/drm_fops.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index 13fdcd1..04f3bcd 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -357,9 +357,11 @@ static int drm_open_helper(struct inode *inode, struct file *filp,
 			pci_dev_put(pci_dev);
 		}
 		if (!dev->hose) {
-			struct pci_bus *b = pci_bus_b(pci_root_buses.next);
-			if (b)
+			struct pci_bus *b = pci_get_next_root_bus(NULL);
+			if (b) {
 				dev->hose = b->sysdata;
+				pci_bus_put(b);
+			}
 		}
 	}
 #endif
-- 
1.8.1.2

[RFC PATCH v2, part 2 14/18] PCI, EDAC: use hotplug-safe PCI bus iterators to walk PCI buses

[Jiang Liu]

Enhance EDAC drviers to use hotplug-safe iterators to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Doug Thompson <dougthompson@xmission.com>
Cc: linux-edac@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/edac/i7core_edac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
index 0ec3e95..39d5823 100644
--- a/drivers/edac/i7core_edac.c
+++ b/drivers/edac/i7core_edac.c
@@ -1296,7 +1296,7 @@ static unsigned i7core_pci_lastbus(void)
 	int last_bus = 0, bus;
 	struct pci_bus *b = NULL;
 
-	while ((b = pci_find_next_bus(b)) != NULL) {
+	for_each_pci_root_bus(b)
 		bus = b->number;
 		edac_dbg(0, "Found bus %d\n", bus);
 		if (bus > last_bus)
-- 
1.8.1.2

[RFC PATCH v2, part 2 15/18] PCI, via-camera: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance via-camera drviers to use hotplug-safe iterators to walk
PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Daniel Drake <dsd@laptop.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Javier Martin <javier.martin@vista-silicon.com>
Cc: linux-media@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/media/platform/via-camera.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/via-camera.c b/drivers/media/platform/via-camera.c
index b051c4a..ef10136 100644
--- a/drivers/media/platform/via-camera.c
+++ b/drivers/media/platform/via-camera.c
@@ -1284,7 +1284,8 @@ static struct video_device viacam_v4l_template = {
 
 static bool viacam_serial_is_enabled(void)
 {
-	struct pci_bus *pbus = pci_find_bus(0, 0);
+	struct pci_bus *pbus = pci_get_bus(0, 0);
+	bool ret = false;
 	u8 cbyte;
 
 	if (!pbus)
@@ -1292,18 +1293,21 @@ static bool viacam_serial_is_enabled(void)
 	pci_bus_read_config_byte(pbus, VIACAM_SERIAL_DEVFN,
 			VIACAM_SERIAL_CREG, &cbyte);
 	if ((cbyte & VIACAM_SERIAL_BIT) == 0)
-		return false; /* Not enabled */
+		goto out; /* Not enabled */
 	if (override_serial == 0) {
 		printk(KERN_NOTICE "Via camera: serial port is enabled, " \
 				"refusing to load.\n");
 		printk(KERN_NOTICE "Specify override_serial=1 to force " \
 				"module loading.\n");
-		return true;
+		ret = true;
+		goto out;
 	}
 	printk(KERN_NOTICE "Via camera: overriding serial port\n");
 	pci_bus_write_config_byte(pbus, VIACAM_SERIAL_DEVFN,
 			VIACAM_SERIAL_CREG, cbyte & ~VIACAM_SERIAL_BIT);
-	return false;
+out:
+	pci_bus_put(pbus);
+	return ret;
 }
 
 static struct ov7670_config sensor_cfg = {
-- 
1.8.1.2

[RFC PATCH v2, part 2 16/18] PCI, iommu: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance iommu drviers to use hotplug-safe iterators to walk
PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Donald Dutile <ddutile@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: "Li, Zhen-Hua" <zhen-hual@hp.com>
Cc: iommu@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/iommu/amd_iommu.c | 4 +++-
 drivers/iommu/dmar.c      | 6 ++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index e046d7a..d6fdf94 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -357,6 +357,7 @@ static int init_iommu_group(struct device *dev)
 	struct iommu_dev_data *dev_data;
 	struct iommu_group *group;
 	struct pci_dev *dma_pdev;
+	struct pci_bus *b = NULL;
 	int ret;
 
 	group = iommu_group_get(dev);
@@ -393,7 +394,7 @@ static int init_iommu_group(struct device *dev)
 		 * the alias.  Be careful to also test the parent device if
 		 * we think the alias is the root of the group.
 		 */
-		bus = pci_find_bus(0, alias >> 8);
+		b = bus = pci_find_bus(0, alias >> 8);
 		if (!bus)
 			goto use_group;
 
@@ -413,6 +414,7 @@ static int init_iommu_group(struct device *dev)
 	dma_pdev = get_isolation_root(pci_dev_get(to_pci_dev(dev)));
 use_pdev:
 	ret = use_pdev_iommu_group(dma_pdev, dev);
+	pci_bus_put(b);
 	pci_dev_put(dma_pdev);
 	return ret;
 use_group:
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index e5cdaf8..5bb3cdc 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -67,12 +67,12 @@ static void __init dmar_register_drhd_unit(struct dmar_drhd_unit *drhd)
 static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
 					   struct pci_dev **dev, u16 segment)
 {
-	struct pci_bus *bus;
+	struct pci_bus *b, *bus;
 	struct pci_dev *pdev = NULL;
 	struct acpi_dmar_pci_path *path;
 	int count;
 
-	bus = pci_find_bus(segment, scope->bus);
+	b = bus = pci_find_bus(segment, scope->bus);
 	path = (struct acpi_dmar_pci_path *)(scope + 1);
 	count = (scope->length - sizeof(struct acpi_dmar_device_scope))
 		/ sizeof(struct acpi_dmar_pci_path);
@@ -97,6 +97,8 @@ static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
 		count --;
 		bus = pdev->subordinate;
 	}
+	pci_bus_put(b);
+
 	if (!pdev) {
 		pr_warn("Device scope device [%04x:%02x:%02x.%02x] not found\n",
 			segment, scope->bus, path->dev, path->fn);
-- 
1.8.1.2

[RFC PATCH v2, part 2 17/18] PCI, eeepc-laptop: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance eeepc-laptop drvier to use hotplug-safe iterators to walk
PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Cc: acpi4asus-user@lists.sourceforge.net
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/platform/x86/eeepc-laptop.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
index 5d26e70..6291b4f 100644
--- a/drivers/platform/x86/eeepc-laptop.c
+++ b/drivers/platform/x86/eeepc-laptop.c
@@ -759,7 +759,7 @@ static struct hotplug_slot_ops eeepc_hotplug_slot_ops = {
 static int eeepc_setup_pci_hotplug(struct eeepc_laptop *eeepc)
 {
 	int ret = -ENOMEM;
-	struct pci_bus *bus = pci_find_bus(0, 1);
+	struct pci_bus *bus = pci_get_bus(0, 1);
 
 	if (!bus) {
 		pr_err("Unable to find wifi PCI bus\n");
@@ -787,6 +787,8 @@ static int eeepc_setup_pci_hotplug(struct eeepc_laptop *eeepc)
 		goto error_register;
 	}
 
+	pci_bus_put(bus);
+
 	return 0;
 
 error_register:
@@ -795,6 +797,7 @@ error_info:
 	kfree(eeepc->hotplug_slot);
 	eeepc->hotplug_slot = NULL;
 error_slot:
+	pci_bus_put(bus);
 	return ret;
 }
 
-- 
1.8.1.2

[RFC PATCH v2, part 2 18/18] PCI, asus-wmi: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance asus-wmi drvier to use hotplug-safe iterators to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Cc: acpi4asus-user@lists.sourceforge.net
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/platform/x86/asus-wmi.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index c11b242..f92db4c 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -596,7 +596,7 @@ static bool asus_wlan_rfkill_blocked(struct asus_wmi *asus)
 static void asus_rfkill_hotplug(struct asus_wmi *asus)
 {
 	struct pci_dev *dev;
-	struct pci_bus *bus;
+	struct pci_bus *bus = NULL;
 	bool blocked;
 	bool absent;
 	u32 l;
@@ -611,7 +611,7 @@ static void asus_rfkill_hotplug(struct asus_wmi *asus)
 		rfkill_set_sw_state(asus->wlan.rfkill, blocked);
 
 	if (asus->hotplug_slot) {
-		bus = pci_find_bus(0, 1);
+		bus = pci_get_bus(0, 1);
 		if (!bus) {
 			pr_warn("Unable to find PCI bus 1?\n");
 			goto out_unlock;
@@ -657,6 +657,7 @@ static void asus_rfkill_hotplug(struct asus_wmi *asus)
 
 out_unlock:
 	mutex_unlock(&asus->hotplug_lock);
+	pci_bus_put(bus);
 }
 
 static void asus_rfkill_notify(acpi_handle handle, u32 event, void *data)
@@ -748,7 +749,7 @@ static void asus_hotplug_work(struct work_struct *work)
 static int asus_setup_pci_hotplug(struct asus_wmi *asus)
 {
 	int ret = -ENOMEM;
-	struct pci_bus *bus = pci_find_bus(0, 1);
+	struct pci_bus *bus = pci_get_bus(0, 1);
 
 	if (!bus) {
 		pr_err("Unable to find wifi PCI bus\n");
@@ -782,6 +783,7 @@ static int asus_setup_pci_hotplug(struct asus_wmi *asus)
 		pr_err("Unable to register hotplug slot - %d\n", ret);
 		goto error_register;
 	}
+	pci_bus_put(bus);
 
 	return 0;
 
@@ -793,6 +795,7 @@ error_info:
 error_slot:
 	destroy_workqueue(asus->hotplug_workqueue);
 error_workqueue:
+	pci_bus_put(bus);
 	return ret;
 }
 
-- 
1.8.1.2

Re: [RFC PATCH v2, part 2 01/18] PCI: introduce hotplug-safe PCI bus iterators

[Greg Kroah-Hartman]

On Wed, May 15, 2013 at 12:51:45AM +0800, Jiang Liu wrote:
> +EXPORT_SYMBOL(pci_bus_exists);

EXPORT_SYMBOL_GPL()?  Same for the other new exports?

thanks,

greg k-h

Re: [RFC PATCH v2, part 2 02/18] PCI, core: use hotplug-safe iterators to walk PCI buses

[Yinghai Lu]

On Tue, May 14, 2013 at 9:51 AM, Jiang Liu <liuj97@gmail.com> wrote:
> Enhance PCI core to use hotplug-safe iterators to walk PCI buses.
>
> In other words, replace pci_find_bus(), pci_find_next_bus() and
> pci_root_buses with pci_bus_exists(), pci_get_bus(), pci_get_next_bus()
> and pci_get_next_root_bus() etc.

good changes.

Acked-by:  Yinghai Lu <yinghai@kernel.org>

Re: [RFC PATCH v2, part 2 01/18] PCI: introduce hotplug-safe PCI bus iterators

[Yinghai Lu]

On Tue, May 14, 2013 at 9:51 AM, Jiang Liu <liuj97@gmail.com> wrote:
> Introduce hotplug-safe PCI bus iterators as below, which hold a
> reference on the returned PCI bus object.
> bool pci_bus_exists(int domain, int busnr);
> struct pci_bus *pci_get_bus(int domain, int busnr);
> struct pci_bus *pci_get_next_bus(struct pci_bus *from);
> struct pci_bus *pci_get_next_root_bus(struct pci_bus *from);
> #define for_each_pci_bus(b) for (b = NULL; (b = pci_get_next_bus(b)); )
> #define for_each_pci_root_bus(b)  \
>                 for (b = NULL; (b = pci_get_next_root_bus(b)); )
>
> The long-term goal is to remove hotplug-unsafe pci_find_bus(),
> pci_find_next_bus() and the global pci_root_buses list.
>
> These new interfaces may be a littler slower than existing interfaces,
> but it should be acceptable because they are not used on hot paths.
>
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> Cc: linux-pci@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org

Acked-by: Yinghai Lu <yinghai@kernel.org>

Re: [RFC PATCH v2, part 2 03/18] PCI, hotplug: use hotplug-safe iterators to walk PCI buses

[Yinghai Lu]

On Tue, May 14, 2013 at 9:51 AM, Jiang Liu <liuj97@gmail.com> wrote:
> Enhance PCI hotplug drivers to use hotplug-safe iterators to walk
> PCI buses.
>
> In other words, replace pci_find_bus(), pci_find_next_bus() and
> pci_root_buses with pci_bus_exists(), pci_get_bus(), pci_get_next_bus()
> and pci_get_next_root_bus() etc.
>
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> Cc: Yinghai Lu <yinghai@kernel.org>
> Cc: Jiri Kosina <jkosina@suse.cz>
> Cc: Masanari Iida <standby24x7@gmail.com>
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> Cc: Toshi Kani <toshi.kani@hp.com>
> Cc: linux-pci@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  drivers/pci/hotplug-pci.c          | 2 +-
>  drivers/pci/hotplug/ibmphp_core.c  | 8 +++++---
>  drivers/pci/hotplug/ibmphp_ebda.c  | 8 ++++++--
>  drivers/pci/hotplug/sgi_hotplug.c  | 3 ++-
>  drivers/pci/hotplug/shpchp_sysfs.c | 2 +-
>  5 files changed, 15 insertions(+), 8 deletions(-)

Acked-by: Yinghai Lu <yinghai@kernel.org>

Re: [RFC PATCH v2, part 2 11/18] PCI, x86: use hotplug-safe iterators to walk PCI buses

[Yinghai Lu]

On Tue, May 14, 2013 at 9:51 AM, Jiang Liu <liuj97@gmail.com> wrote:
> Enhance x86 architecture specific code to use hotplug-safe iterators
> to walk PCI buses.
>
> In other words, replace pci_find_bus(), pci_find_next_bus() and
> pci_root_buses with pci_bus_exists(), pci_get_bus(), pci_get_next_bus()
> and pci_get_next_root_bus() etc.
>
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: x86@kernel.org
> Cc: Myron Stowe <myron.stowe@redhat.com>
> Cc: Yijing Wang <wangyijing@huawei.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Matthew Garrett <mjg@redhat.com>
> Cc: Yinghai Lu <yinghai@kernel.org>
> Cc: linux-kernel@vger.kernel.org
> ---
>  arch/x86/pci/acpi.c   | 3 ++-
>  arch/x86/pci/common.c | 3 ++-
>  arch/x86/pci/i386.c   | 9 ++++-----
>  arch/x86/pci/irq.c    | 2 +-
>  arch/x86/pci/legacy.c | 2 +-
>  5 files changed, 10 insertions(+), 9 deletions(-)

Acked-by: Yinghai Lu <yinghai@kernel.org>

Re: [RFC PATCH v2, part 2 12/18] PCI, ACPI: use hotplug-safe iterators to walk PCI buses

[Rafael J. Wysocki]

On Wednesday, May 15, 2013 12:51:56 AM Jiang Liu wrote:
> Enhance ACPI reset drvier to use hotplug-safe iterators to walk PCI buses.
> 
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> Cc: Len Brown <lenb@kernel.org>
> Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
> Cc: linux-acpi@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  drivers/acpi/reboot.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c
> index a6c77e8b..532dd6d 100644
> --- a/drivers/acpi/reboot.c
> +++ b/drivers/acpi/reboot.c
> @@ -33,7 +33,7 @@ void acpi_reboot(void)
>  	switch (rr->space_id) {
>  	case ACPI_ADR_SPACE_PCI_CONFIG:
>  		/* The reset register can only live on bus 0. */
> -		bus0 = pci_find_bus(0, 0);
> +		bus0 = pci_get_bus(0, 0);
>  		if (!bus0)
>  			return;
>  		/* Form PCI device/function pair. */
> @@ -43,6 +43,7 @@ void acpi_reboot(void)
>  		/* Write the value that resets us. */
>  		pci_bus_write_config_byte(bus0, devfn,
>  				(rr->address & 0xffff), reset_value);
> +		pci_bus_put(bus0);
>  		break;
>  
>  	case ACPI_ADR_SPACE_SYSTEM_MEMORY:
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [RFC PATCH v2, part 2 16/18] PCI, iommu: use hotplug-safe iterators to walk PCI buses

[Don Dutile]

On 05/14/2013 12:52 PM, Jiang Liu wrote:
> Enhance iommu drviers to use hotplug-safe iterators to walk
> PCI buses.
>
> Signed-off-by: Jiang Liu<jiang.liu@huawei.com>
> Cc: Joerg Roedel<joro@8bytes.org>
> Cc: Ingo Molnar<mingo@kernel.org>
> Cc: Donald Dutile<ddutile@redhat.com>
> Cc: Hannes Reinecke<hare@suse.de>
> Cc: "Li, Zhen-Hua"<zhen-hual@hp.com>
> Cc: iommu@lists.linux-foundation.org
> Cc: linux-kernel@vger.kernel.org
> ---
>   drivers/iommu/amd_iommu.c | 4 +++-
>   drivers/iommu/dmar.c      | 6 ++++--
>   2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index e046d7a..d6fdf94 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -357,6 +357,7 @@ static int init_iommu_group(struct device *dev)
>   	struct iommu_dev_data *dev_data;
>   	struct iommu_group *group;
>   	struct pci_dev *dma_pdev;
> +	struct pci_bus *b = NULL;
>   	int ret;
>
>   	group = iommu_group_get(dev);
> @@ -393,7 +394,7 @@ static int init_iommu_group(struct device *dev)
>   		 * the alias.  Be careful to also test the parent device if
>   		 * we think the alias is the root of the group.
>   		 */
> -		bus = pci_find_bus(0, alias>>  8);
> +		b = bus = pci_find_bus(0, alias>>  8);
>   		if (!bus)
>   			goto use_group;
>
> @@ -413,6 +414,7 @@ static int init_iommu_group(struct device *dev)
>   	dma_pdev = get_isolation_root(pci_dev_get(to_pci_dev(dev)));
>   use_pdev:
>   	ret = use_pdev_iommu_group(dma_pdev, dev);
> +	pci_bus_put(b);
pci_find_bus() does a pci_bus_put() after the pci_get_bus();
is this needed, or did you mean to make the above patch pci_get_bus() ?

>   	pci_dev_put(dma_pdev);
>   	return ret;
>   use_group:
> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> index e5cdaf8..5bb3cdc 100644
> --- a/drivers/iommu/dmar.c
> +++ b/drivers/iommu/dmar.c
> @@ -67,12 +67,12 @@ static void __init dmar_register_drhd_unit(struct dmar_drhd_unit *drhd)
>   static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
>   					   struct pci_dev **dev, u16 segment)
>   {
> -	struct pci_bus *bus;
> +	struct pci_bus *b, *bus;
>   	struct pci_dev *pdev = NULL;
>   	struct acpi_dmar_pci_path *path;
>   	int count;
>
> -	bus = pci_find_bus(segment, scope->bus);
> +	b = bus = pci_find_bus(segment, scope->bus);
>   	path = (struct acpi_dmar_pci_path *)(scope + 1);
>   	count = (scope->length - sizeof(struct acpi_dmar_device_scope))
>   		/ sizeof(struct acpi_dmar_pci_path);
> @@ -97,6 +97,8 @@ static int __init dmar_parse_one_dev_scope(struct acpi_dmar_device_scope *scope,
>   		count --;
>   		bus = pdev->subordinate;
>   	}
> +	pci_bus_put(b);
ditto.

> +
>   	if (!pdev) {
>   		pr_warn("Device scope device [%04x:%02x:%02x.%02x] not found\n",
>   			segment, scope->bus, path->dev, path->fn);

Re: [RFC PATCH v2, part 2 09/18] PCI, PPC: use hotplug-safe iterators to walk PCI buses

[Benjamin Herrenschmidt]

On Wed, 2013-05-15 at 00:51 +0800, Jiang Liu wrote:
> Enhance PPC architecture specific code to use hotplug-safe iterators
> to walk PCI buses.

I was about to ack it but then I saw:

> diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
> index 51a133a..a41c6dd 100644
> --- a/arch/powerpc/kernel/pci_64.c
> +++ b/arch/powerpc/kernel/pci_64.c
> @@ -208,7 +208,6 @@ long sys_pciconfig_iobase(long which, unsigned long in_bus,
>  			  unsigned long in_devfn)
>  {
>  	struct pci_controller* hose;
> -	struct list_head *ln;
>  	struct pci_bus *bus = NULL;
>  	struct device_node *hose_node;
>  
> @@ -229,18 +228,16 @@ long sys_pciconfig_iobase(long which, unsigned long in_bus,
>  	/* That syscall isn't quite compatible with PCI domains, but it's
>  	 * used on pre-domains setup. We return the first match
>  	 */
> -
> -	for (ln = pci_root_buses.next; ln != &pci_root_buses; ln = ln->next) {
> -		bus = pci_bus_b(ln);
> -		if (in_bus >= bus->number && in_bus <= bus->busn_res.end)
> +	for_each_pci_root_bus(bus)
> +		if (in_bus >= bus->number && in_bus <= bus->busn_res.end &&
> +		    bus->dev.of_node)
>  			break;
> -		bus = NULL;
> -	}
> -	if (bus == NULL || bus->dev.of_node == NULL)
> +	if (bus == NULL)
>  		return -ENODEV;

You just removed the NULL check for the of_node field...
 
>  	hose_node = bus->dev.of_node;
>  	hose = PCI_DN(hose_node)->phb;

Which is dereferrenced here.	

> +	pci_bus_put(bus);

On the other hand, the whole thing can probably be using
pci_bus_to_host() instead.... the above code is bitrotted.

>  	switch (which) {
>  	case IOBASE_BRIDGE_NUMBER:
 
Cheeers,
Ben.

Re: [RFC PATCH v2, part 2 01/18] PCI: introduce hotplug-safe PCI bus iterators

[Liu Jiang]

On 05/15/2013 01:05 AM, Greg Kroah-Hartman wrote:
> On Wed, May 15, 2013 at 12:51:45AM +0800, Jiang Liu wrote:
>> +EXPORT_SYMBOL(pci_bus_exists);
> EXPORT_SYMBOL_GPL()?  Same for the other new exports?
>
> thanks,
>
> greg k-h
Sure, will change to EXPORT_SYMBOL_GPL in next version.
Thanks for review!
Gerry

Re: [RFC PATCH v2, part 2 01/18] PCI: introduce hotplug-safe PCI bus iterators

[Liu Jiang]

On 05/15/2013 01:05 AM, Greg Kroah-Hartman wrote:
> On Wed, May 15, 2013 at 12:51:45AM +0800, Jiang Liu wrote:
>> +EXPORT_SYMBOL(pci_bus_exists);
> EXPORT_SYMBOL_GPL()?  Same for the other new exports?
>
> thanks,
>
> greg k-h
Hi Greg,
     Only pci_root_buses from drivers/pci/search.c is exported as GPL,
all other functions from that file are exported as EXPORT_SYMBOL().
So should we keep those new interfaces as EXPORT_SYMBOL() too?
Thanks,
Gerry

Re: [RFC PATCH v2, part 2 09/18] PCI, PPC: use hotplug-safe iterators to walk PCI buses

[Liu Jiang]

On 05/15/2013 07:30 AM, Benjamin Herrenschmidt wrote:
> On Wed, 2013-05-15 at 00:51 +0800, Jiang Liu wrote:
>> Enhance PPC architecture specific code to use hotplug-safe iterators
>> to walk PCI buses.
> I was about to ack it but then I saw:
>
>> diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
>> index 51a133a..a41c6dd 100644
>> --- a/arch/powerpc/kernel/pci_64.c
>> +++ b/arch/powerpc/kernel/pci_64.c
>> @@ -208,7 +208,6 @@ long sys_pciconfig_iobase(long which, unsigned long in_bus,
>>   			  unsigned long in_devfn)
>>   {
>>   	struct pci_controller* hose;
>> -	struct list_head *ln;
>>   	struct pci_bus *bus = NULL;
>>   	struct device_node *hose_node;
>>   
>> @@ -229,18 +228,16 @@ long sys_pciconfig_iobase(long which, unsigned long in_bus,
>>   	/* That syscall isn't quite compatible with PCI domains, but it's
>>   	 * used on pre-domains setup. We return the first match
>>   	 */
>> -
>> -	for (ln = pci_root_buses.next; ln != &pci_root_buses; ln = ln->next) {
>> -		bus = pci_bus_b(ln);
>> -		if (in_bus >= bus->number && in_bus <= bus->busn_res.end)
>> +	for_each_pci_root_bus(bus)
>> +		if (in_bus >= bus->number && in_bus <= bus->busn_res.end &&
>> +		    bus->dev.of_node)
>>   			break;
>> -		bus = NULL;
>> -	}
>> -	if (bus == NULL || bus->dev.of_node == NULL)
>> +	if (bus == NULL)
>>   		return -ENODEV;
> You just removed the NULL check for the of_node field...
Hi Benjamin,
     Thanks for review.
     I just moved the "bus->dev.of_node == NULL" into the above 
for_each_pci_root_bus()
loop:)
     Will send you another version according to your suggestion to use 
pci_bus_to_host()
to simplify the code.
Regards!
Gerry

>   
>>   	hose_node = bus->dev.of_node;
>>   	hose = PCI_DN(hose_node)->phb;
> Which is dereferrenced here.	
>
>> +	pci_bus_put(bus);
> On the other hand, the whole thing can probably be using
> pci_bus_to_host() instead.... the above code is bitrotted.
>
>>   	switch (which) {
>>   	case IOBASE_BRIDGE_NUMBER:
>   
> Cheeers,
> Ben.
>
>

PCI, PPC: use hotplug-safe iterators to walk PCI buses

[Jiang Liu]

Enhance PPC architecture specific code to use hotplug-safe iterators
to walk PCI buses.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Gavin Shan <shangw@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
---
Hi Benjamin,
	How about this version? Use pci_bus_to_host() instead
to simplify code.
Regards!
Gerry
---
 arch/powerpc/kernel/pci-common.c |  4 ++--
 arch/powerpc/kernel/pci_64.c     | 22 ++++++++--------------
 2 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index fa12ae4..26fca09 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -1400,7 +1400,7 @@ void __init pcibios_resource_survey(void)
 	struct pci_bus *b;
 
 	/* Allocate and assign resources */
-	list_for_each_entry(b, &pci_root_buses, node)
+	for_each_pci_root_bus(b)
 		pcibios_allocate_bus_resources(b);
 	pcibios_allocate_resources(0);
 	pcibios_allocate_resources(1);
@@ -1410,7 +1410,7 @@ void __init pcibios_resource_survey(void)
 	 * bus available resources to avoid allocating things on top of them
 	 */
 	if (!pci_has_flag(PCI_PROBE_ONLY)) {
-		list_for_each_entry(b, &pci_root_buses, node)
+		for_each_pci_root_bus(b)
 			pcibios_reserve_legacy_regions(b);
 	}
 
diff --git a/arch/powerpc/kernel/pci_64.c b/arch/powerpc/kernel/pci_64.c
index 51a133a..8bea231 100644
--- a/arch/powerpc/kernel/pci_64.c
+++ b/arch/powerpc/kernel/pci_64.c
@@ -207,10 +207,8 @@ void pcibios_setup_phb_io_space(struct pci_controller *hose)
 long sys_pciconfig_iobase(long which, unsigned long in_bus,
 			  unsigned long in_devfn)
 {
-	struct pci_controller* hose;
-	struct list_head *ln;
-	struct pci_bus *bus = NULL;
-	struct device_node *hose_node;
+	struct pci_controller* hose = NULL;
+	struct pci_bus *bus;
 
 	/* Argh ! Please forgive me for that hack, but that's the
 	 * simplest way to get existing XFree to not lockup on some
@@ -229,19 +227,15 @@ long sys_pciconfig_iobase(long which, unsigned long in_bus,
 	/* That syscall isn't quite compatible with PCI domains, but it's
 	 * used on pre-domains setup. We return the first match
 	 */
-
-	for (ln = pci_root_buses.next; ln != &pci_root_buses; ln = ln->next) {
-		bus = pci_bus_b(ln);
-		if (in_bus >= bus->number && in_bus <= bus->busn_res.end)
+	for_each_pci_root_bus(bus)
+		if (in_bus >= bus->number && in_bus <= bus->busn_res.end) {
+			hose = pci_bus_to_host(bus);
+			pci_bus_put(bus);
 			break;
-		bus = NULL;
-	}
-	if (bus == NULL || bus->dev.of_node == NULL)
+		}
+	if (hose == NULL)
 		return -ENODEV;
 
-	hose_node = bus->dev.of_node;
-	hose = PCI_DN(hose_node)->phb;
-
 	switch (which) {
 	case IOBASE_BRIDGE_NUMBER:
 		return (long)hose->first_busno;
-- 
1.8.1.2

Re: [RFC PATCH v2, part 2 16/18] PCI, iommu: use hotplug-safe iterators to walk PCI buses

[Liu Jiang]

On 05/15/2013 06:13 AM, Don Dutile wrote:
> On 05/14/2013 12:52 PM, Jiang Liu wrote:
>> Enhance iommu drviers to use hotplug-safe iterators to walk
>> PCI buses.
>>
>> Signed-off-by: Jiang Liu<jiang.liu@huawei.com>
>> Cc: Joerg Roedel<joro@8bytes.org>
>> Cc: Ingo Molnar<mingo@kernel.org>
>> Cc: Donald Dutile<ddutile@redhat.com>
>> Cc: Hannes Reinecke<hare@suse.de>
>> Cc: "Li, Zhen-Hua"<zhen-hual@hp.com>
>> Cc: iommu@lists.linux-foundation.org
>> Cc: linux-kernel@vger.kernel.org
>> ---
>>   drivers/iommu/amd_iommu.c | 4 +++-
>>   drivers/iommu/dmar.c      | 6 ++++--
>>   2 files changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
>> index e046d7a..d6fdf94 100644
>> --- a/drivers/iommu/amd_iommu.c
>> +++ b/drivers/iommu/amd_iommu.c
>> @@ -357,6 +357,7 @@ static int init_iommu_group(struct device *dev)
>>       struct iommu_dev_data *dev_data;
>>       struct iommu_group *group;
>>       struct pci_dev *dma_pdev;
>> +    struct pci_bus *b = NULL;
>>       int ret;
>>
>>       group = iommu_group_get(dev);
>> @@ -393,7 +394,7 @@ static int init_iommu_group(struct device *dev)
>>            * the alias.  Be careful to also test the parent device if
>>            * we think the alias is the root of the group.
>>            */
>> -        bus = pci_find_bus(0, alias>>  8);
>> +        b = bus = pci_find_bus(0, alias>>  8);
>>           if (!bus)
>>               goto use_group;
>>
>> @@ -413,6 +414,7 @@ static int init_iommu_group(struct device *dev)
>>       dma_pdev = get_isolation_root(pci_dev_get(to_pci_dev(dev)));
>>   use_pdev:
>>       ret = use_pdev_iommu_group(dma_pdev, dev);
>> +    pci_bus_put(b);
> pci_find_bus() does a pci_bus_put() after the pci_get_bus();
> is this needed, or did you mean to make the above patch pci_get_bus() ?
Hi Don,
     Thanks for review!
     My fault, I should use pci_get_bus() instead, will fix it in next 
version.
Regards!
Gerry


>
>>       pci_dev_put(dma_pdev);
>>       return ret;
>>   use_group:
>> diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
>> index e5cdaf8..5bb3cdc 100644
>> --- a/drivers/iommu/dmar.c
>> +++ b/drivers/iommu/dmar.c
>> @@ -67,12 +67,12 @@ static void __init dmar_register_drhd_unit(struct 
>> dmar_drhd_unit *drhd)
>>   static int __init dmar_parse_one_dev_scope(struct 
>> acpi_dmar_device_scope *scope,
>>                          struct pci_dev **dev, u16 segment)
>>   {
>> -    struct pci_bus *bus;
>> +    struct pci_bus *b, *bus;
>>       struct pci_dev *pdev = NULL;
>>       struct acpi_dmar_pci_path *path;
>>       int count;
>>
>> -    bus = pci_find_bus(segment, scope->bus);
>> +    b = bus = pci_find_bus(segment, scope->bus);
>>       path = (struct acpi_dmar_pci_path *)(scope + 1);
>>       count = (scope->length - sizeof(struct acpi_dmar_device_scope))
>>           / sizeof(struct acpi_dmar_pci_path);
>> @@ -97,6 +97,8 @@ static int __init dmar_parse_one_dev_scope(struct 
>> acpi_dmar_device_scope *scope,
>>           count --;
>>           bus = pdev->subordinate;
>>       }
>> +    pci_bus_put(b);
> ditto.
>
>> +
>>       if (!pdev) {
>>           pr_warn("Device scope device [%04x:%02x:%02x.%02x] not 
>> found\n",
>>               segment, scope->bus, path->dev, path->fn);
>

Re: [RFC PATCH v2, part 2 14/18] PCI, EDAC: use hotplug-safe PCI bus iterators to walk PCI buses

[Gu Zheng]

On 05/15/2013 12:51 AM, Jiang Liu wrote:

> Enhance EDAC drviers to use hotplug-safe iterators to walk PCI buses.
> 
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
> Cc: Doug Thompson <dougthompson@xmission.com>
> Cc: linux-edac@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  drivers/edac/i7core_edac.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
> index 0ec3e95..39d5823 100644
> --- a/drivers/edac/i7core_edac.c
> +++ b/drivers/edac/i7core_edac.c
> @@ -1296,7 +1296,7 @@ static unsigned i7core_pci_lastbus(void)
>  	int last_bus = 0, bus;
>  	struct pci_bus *b = NULL;
>  
> -	while ((b = pci_find_next_bus(b)) != NULL) {
> +	for_each_pci_root_bus(b)

missing the "{":
+	for_each_pci_root_bus(b) {

>  		bus = b->number;
>  		edac_dbg(0, "Found bus %d\n", bus);
>  		if (bus > last_bus)

Re: [RFC PATCH v2, part 2 14/18] PCI, EDAC: use hotplug-safe PCI bus iterators to walk PCI buses

[Liu Jiang]

On Wed 22 May 2013 12:12:19 PM CST, Gu Zheng wrote:
> On 05/15/2013 12:51 AM, Jiang Liu wrote:
>
>> Enhance EDAC drviers to use hotplug-safe iterators to walk PCI buses.
>>
>> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
>> Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
>> Cc: Doug Thompson <dougthompson@xmission.com>
>> Cc: linux-edac@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> ---
>>   drivers/edac/i7core_edac.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/edac/i7core_edac.c b/drivers/edac/i7core_edac.c
>> index 0ec3e95..39d5823 100644
>> --- a/drivers/edac/i7core_edac.c
>> +++ b/drivers/edac/i7core_edac.c
>> @@ -1296,7 +1296,7 @@ static unsigned i7core_pci_lastbus(void)
>>   	int last_bus = 0, bus;
>>   	struct pci_bus *b = NULL;
>>
>> -	while ((b = pci_find_next_bus(b)) != NULL) {
>> +	for_each_pci_root_bus(b)
>
> missing the "{":
> +	for_each_pci_root_bus(b) {
Hi Zheng,
             Thanks for review! Will fix it in next version.
Regards!
Gerry

>
>>   		bus = b->number;
>>   		edac_dbg(0, "Found bus %d\n", bus);
>>   		if (bus > last_bus)
>
>