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

Message ID CAE9FiQVgXfViM22qhB-sKDSTtnhvLDMk0NTiK_G88UogVMuM_w@mail.gmail.com
State Not Applicable
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Commit Message

Yinghai Lu March 26, 2015, 4:31 p.m. UTC 
On Mon, Mar 23, 2015 at 8:34 PM, Yijing Wang <wangyijing@huawei.com> 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

Comments

Yijing Wang March 27, 2015, 2:31 a.m. UTC | #1 
On 2015/3/27 0:31, Yinghai Lu wrote:
> On Mon, Mar 23, 2015 at 8:34 PM, Yijing Wang <wangyijing@huawei.com> 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.

HI Yinghai,
   I think your changes is good, but in this series, we only iterate the pci_host_bridge
in drivers/pci/host-bridge.c. The simple list is enough, of course, if we want to export
this list and support to host bridge hotplug, we must need a new iteration for host bridge,
and your series looks good to me, I read your series history, found Bjorn comment a lot.

So I think Bjorn may have some comments for this.

Thanks!
Yijing.
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Patch

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@kernel.org>

---
 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);