PCI: Introduce pci_alloc_dev(struct pci_bus*) to replace alloc_pci_dev()

Here we introduce a new interface to replace alloc_pci_dev():

    struct pci_dev *pci_alloc_dev(struct pci_bus *bus)

It takes a "struct pci_bus *" argument, so we can alloc a PCI device
on a target PCI bus, and it acquires a reference on the pci_bus.
We use pci_alloc_dev(NULL) to simplify the old alloc_pci_dev(),
and keep it for a while but mark it as __deprecated.

Holding a reference to the pci_bus ensures that referencing
pci_dev->bus is valid as long as the pci_dev is valid.

[bhelgaas: keep existing "return error early" structure in pci_alloc_dev()]
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/probe.c

@@ -1200,7 +1200,7 @@ static void pci_release_bus_bridge_dev(struct device *dev)
 	kfree(bridge);
 }
 
-struct pci_dev *alloc_pci_dev(void)
+struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
 {
 	struct pci_dev *dev;
 
@@ -1210,9 +1210,16 @@ struct pci_dev *alloc_pci_dev(void)
 
 	INIT_LIST_HEAD(&dev->bus_list);
 	dev->dev.type = &pci_dev_type;
+	dev->bus = pci_bus_get(bus);
 
 	return dev;
 }
+EXPORT_SYMBOL(pci_alloc_dev);
+
+struct pci_dev *alloc_pci_dev(void)
+{
+	return pci_alloc_dev(NULL);
+}
 EXPORT_SYMBOL(alloc_pci_dev);
 
 bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,

include/linux/pci.h

@@ -364,7 +364,8 @@ static inline struct pci_dev *pci_physfn(struct pci_dev *dev)
 	return dev;
 }
 
-struct pci_dev *alloc_pci_dev(void);
+struct pci_dev *pci_alloc_dev(struct pci_bus *bus);
+struct pci_dev * __deprecated alloc_pci_dev(void);
 
 #define	to_pci_dev(n) container_of(n, struct pci_dev, dev)
 #define for_each_pci_dev(d) while ((d = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, d)) != NULL)