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

[Yijing Wang]

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().

Signed-off-by: Yijing Wang <wangyijing at huawei.com>
---
 drivers/pci/host-bridge.c |   41 ++++++++++++++++++++++++++++++++++++++++-
 drivers/pci/probe.c       |    9 +--------
 include/linux/pci.h       |    1 +
 3 files changed, 42 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/host-bridge.c b/drivers/pci/host-bridge.c
index 1a9834b..8af6d51 100644
--- a/drivers/pci/host-bridge.c
+++ b/drivers/pci/host-bridge.c
@@ -8,6 +8,9 @@
 
 #include "pci.h"
 
+static LIST_HEAD(pci_host_bridge_list);
+static DEFINE_MUTEX(pci_host_mutex);
+
 static void pci_release_host_bridge_dev(struct device *dev)
 {
 	struct pci_host_bridge *bridge = to_pci_host_bridge(dev);
@@ -41,12 +44,29 @@ static void pci_host_update_busn_res(
 	pci_add_resource(resources, &host->busn_res);
 }
 
+static bool pci_host_busn_res_overlap(
+		struct pci_host_bridge *new, struct pci_host_bridge *old)
+{
+	struct resource_entry *entry;
+	struct resource *res1 = NULL, *res2 = NULL;
+
+	resource_list_for_each_entry(entry, &old->windows)
+		if (entry->res->flags & IORESOURCE_BUS)
+			res1 = entry->res;
+
+	resource_list_for_each_entry(entry, &new->windows)
+		if (entry->res->flags & IORESOURCE_BUS)
+			res2 = entry->res;
+
+	return resource_overlaps(res1, res2);
+}
+
 struct pci_host_bridge *pci_create_host_bridge(
 		struct device *parent, int domain, int bus,
 		struct list_head *resources)
 {
 	int error;
-	struct pci_host_bridge *host;
+	struct pci_host_bridge *host, *tmp;
 	struct resource_entry *window, *n;
 
 	host = kzalloc(sizeof(*host), GFP_KERNEL);
@@ -65,6 +85,21 @@ struct pci_host_bridge *pci_create_host_bridge(
 	 */
 	host->domain = domain;
 	pci_host_assign_domain_nr(host);
+	mutex_lock(&pci_host_mutex);
+	list_for_each_entry(tmp, &pci_host_bridge_list, list) {
+		if (tmp->domain != host->domain
+			  || pci_host_busn_res_overlap(host, tmp)) {
+			pr_warn("pci host bridge pci%04x:%02x exist\n",
+					host->domain, bus);
+			mutex_unlock(&pci_host_mutex);
+			pci_free_resource_list(&host->windows);
+			kfree(host);
+			return NULL;
+		}
+	}
+	list_add_tail(&host->list, &pci_host_bridge_list);
+	mutex_unlock(&pci_host_mutex);
+
 	host->dev.release = pci_release_host_bridge_dev;
 	dev_set_name(&host->dev, "pci%04x:%02x",
 			host->domain, bus);
@@ -80,6 +115,10 @@ struct pci_host_bridge *pci_create_host_bridge(
 
 void pci_free_host_bridge(struct pci_host_bridge *host)
 {
+	mutex_lock(&pci_host_mutex);
+	list_del(&host->list);
+	mutex_unlock(&pci_host_mutex);
+
 	device_unregister(&host->dev);
 }
 
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 25ac741..8517d1b 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1869,7 +1869,7 @@ static struct pci_bus *__pci_create_root_bus(
 		void *sysdata)
 {
 	int error;
-	struct pci_bus *b, *b2;
+	struct pci_bus *b;
 	struct resource_entry *window;
 	struct device *parent;
 	struct resource *res;
@@ -1887,12 +1887,6 @@ static struct pci_bus *__pci_create_root_bus(
 	b->number = b->busn_res.start =
 		pci_host_first_busnr(bridge);
 	pci_bus_assign_domain_nr(b, parent);
-	b2 = pci_find_bus(pci_domain_nr(b), b->number);
-	if (b2) {
-		/* If we already got to this bus through a different bridge, ignore it */
-		dev_dbg(&b2->dev, "bus already known\n");
-		goto err_out;
-	}
 
 	bridge->bus = b;
 	b->bridge = get_device(&bridge->dev);
@@ -1952,7 +1946,6 @@ static struct pci_bus *__pci_create_root_bus(
 
 put_dev:
 	put_device(&bridge->dev);
-err_out:
 	kfree(b);
 	return NULL;
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f189dfb..91cba01 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -407,6 +407,7 @@ struct pci_host_bridge {
 	/* we use default bus resource if no bus resource provided */
 	struct resource busn_res;
 	struct list_head windows;	/* resource_entry */
+	struct list_head list;
 	void (*release_fn)(struct pci_host_bridge *);
 	void *release_data;
 };
-- 
1.7.1