Re: [PATCH v8 10/30] PCI: Introduce pci_host_bridge_list to manage host bridges

[Yinghai Lu]

On Mon, Mar 23, 2015 at 8:34 PM, Yijing Wang <wangyijing@xxxxxxxxxx> wrote:
> Introduce pci_host_bridge_list to manage pci host
> bridges in system, this make us have the ability
> to check whether the new host would conflict with
> existing one. Then we could remove bus alreay exist
> check in __pci_create_root_bus().

Can we use bus_type instead?
Then we can use bus_find_device for the host_bridge enumeration.

Please refer the patches that I sent out couple years ago.

Thanks

Yinghai
Subject: [PATCH] PCI: Add dummy bus_type for pci_host_bridge

Need to use it for looping registered host_bridges, and kill
pci_root_buses list later.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
 drivers/pci/pci-driver.c |   10 ++++++++++
 drivers/pci/probe.c      |    1 +
 include/linux/pci.h      |    2 ++
 3 files changed, 13 insertions(+)

Index: linux-2.6/include/linux/pci.h
===================================================================
--- linux-2.6.orig/include/linux/pci.h
+++ linux-2.6/include/linux/pci.h
@@ -735,6 +735,7 @@ enum pcie_bus_config_types {
 
 extern enum pcie_bus_config_types pcie_bus_config;
 
+extern struct bus_type pci_host_bridge_bus_type;
 extern struct bus_type pci_bus_type;
 
 /* Do NOT directly access these two variables, unless you are arch-specific PCI
@@ -808,6 +809,7 @@ void pci_stop_root_bus(struct pci_bus *b
 void pci_remove_root_bus(struct pci_bus *bus);
 void pci_setup_cardbus(struct pci_bus *bus);
 void pci_sort_breadthfirst(void);
+#define dev_is_pci_host_bridge(d) ((d)->bus == &pci_host_bridge_bus_type)
 #define dev_is_pci(d) ((d)->bus == &pci_bus_type)
 #define dev_is_pf(d) ((dev_is_pci(d) ? to_pci_dev(d)->is_physfn : false))
 #define dev_num_vf(d) ((dev_is_pci(d) ? pci_num_vf(to_pci_dev(d)) : 0))
Index: linux-2.6/drivers/pci/pci-driver.c
===================================================================
--- linux-2.6.orig/drivers/pci/pci-driver.c
+++ linux-2.6/drivers/pci/pci-driver.c
@@ -1408,6 +1408,16 @@ struct bus_type pci_bus_type = {
 };
 EXPORT_SYMBOL(pci_bus_type);
 
+struct bus_type pci_host_bridge_bus_type = {
+	.name           = "pci_host_bridge",
+};
+
+static int __init pci_host_bridge_driver_init(void)
+{
+	return bus_register(&pci_host_bridge_bus_type);
+}
+postcore_initcall(pci_host_bridge_driver_init);
+
 static int __init pci_driver_init(void)
 {
 	return bus_register(&pci_bus_type);
Index: linux-2.6/drivers/pci/probe.c
===================================================================
--- linux-2.6.orig/drivers/pci/probe.c
+++ linux-2.6/drivers/pci/probe.c
@@ -1949,6 +1949,7 @@ struct pci_bus *pci_create_root_bus(stru
 		goto err_out;
 
 	bridge->dev.parent = parent;
+	bridge->dev.bus = &pci_host_bridge_bus_type;
 	bridge->dev.release = pci_release_host_bridge_dev;
 	dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
 	error = pcibios_root_bridge_prepare(bridge);
Subject: [PATCH] PCI: Add for_each_pci_host_bridge() and pci_get_next_host_bridge

Now we have pci_root_buses list, and there is lots of iteration with
list_of_each of it, that is not safe after we add pci root bus hotplug
support after booting stage.

Also pci_find_next_bus is pretty misleading name, and it is only finding
next root bus instead of regular pci bus.

Add pci_get_next_host_bridge and use bus_find_device in driver core to
iterate host bridge and the same time get root bus.

In folllowing patches will replace searching root bus with searching host_bridge.
after using with that host-bridge, will need to call put device to release
reference if break early from the loop.

After those replacing, we even could kill pci_root_buses list.

-v2: fixes compiling error when CONFIG_PCI is not defined that Fengguang found.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
 drivers/pci/search.c |   24 ++++++++++++++++++++++++
 include/linux/pci.h  |    9 +++++++++
 2 files changed, 33 insertions(+)

Index: linux-2.6/include/linux/pci.h
===================================================================
--- linux-2.6.orig/include/linux/pci.h
+++ linux-2.6/include/linux/pci.h
@@ -409,6 +409,8 @@ struct pci_host_bridge {
 };
 
 #define	to_pci_host_bridge(n) container_of(n, struct pci_host_bridge, dev)
+#define for_each_pci_host_bridge(d) while ((d = pci_get_next_host_bridge(d)) != NULL)
+
 void pci_set_host_bridge_release(struct pci_host_bridge *bridge,
 		     void (*release_fn)(struct pci_host_bridge *),
 		     void *release_data);
@@ -831,6 +833,7 @@ int pci_find_ht_capability(struct pci_de
 int pci_find_next_ht_capability(struct pci_dev *dev, int pos, int ht_cap);
 struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
 
+struct pci_host_bridge *pci_get_next_host_bridge(struct pci_host_bridge *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,
@@ -1447,6 +1450,12 @@ static inline int pci_domain_nr(struct p
 static inline struct pci_dev *pci_dev_get(struct pci_dev *dev) { return NULL; }
 static inline int pci_get_new_domain_nr(void) { return -ENOSYS; }
 
+static inline struct pci_host_bridge *pci_get_next_host_bridge(
+			struct pci_host_bridge *host_bridge)
+{
+	return NULL;
+}
+
 #define dev_is_pci(d) (false)
 #define dev_is_pf(d) (false)
 #define dev_num_vf(d) (0)
Index: linux-2.6/drivers/pci/search.c
===================================================================
--- linux-2.6.orig/drivers/pci/search.c
+++ linux-2.6/drivers/pci/search.c
@@ -231,6 +231,30 @@ struct pci_dev *pci_get_domain_bus_and_s
 }
 EXPORT_SYMBOL(pci_get_domain_bus_and_slot);
 
+static int match_pci_host_bridge(struct device *dev, void *data)
+{
+	return 1;
+}
+
+struct pci_host_bridge *pci_get_next_host_bridge(struct pci_host_bridge *from)
+{
+	struct device *dev;
+	struct device *dev_start = NULL;
+	struct pci_host_bridge *bridge = NULL;
+
+	WARN_ON(in_interrupt());
+	if (from)
+		dev_start = &from->dev;
+	dev = bus_find_device(&pci_host_bridge_bus_type, dev_start, NULL,
+			      match_pci_host_bridge);
+	if (dev)
+		bridge = to_pci_host_bridge(dev);
+	if (from)
+		put_device(&from->dev);
+	return bridge;
+}
+EXPORT_SYMBOL_GPL(pci_get_next_host_bridge);
+
 static int match_pci_dev_by_id(struct device *dev, void *data)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);