Function pci_find_bus() is not hotplug safe because it doesn't hold any
reference on the returned bus, so the bus may be destroyed by hotplug
operations just after returning from pci_find_bus.
This patch introduces a hotplug safe interface to get and lock a specific
PCI bus. It also provides several help interfaces to reduce code complexity.
Signed-off-by: Jiang Liu <liu...@gmail.com>
---
drivers/pci/bus.c | 34 ++++++++++++++++++++++++++++++++++
drivers/pci/search.c | 44 ++++++++++++++++++++++++++++++++++----------
include/linux/pci.h | 10 ++++++++++
3 files changed, 78 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index aa25fcf..b6aacaa 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -426,6 +426,40 @@ void pci_bus_change_state(struct pci_bus *bus, int old,
int new, bool unlock)
}
EXPORT_SYMBOL(pci_bus_change_state);
+struct pci_bus *__pci_get_and_lock_bus(int domain, int busnr, int states)
+{
+ struct pci_bus *bus;
+
+ bus = pci_get_bus(domain, busnr);
+ if (bus && pci_bus_lock_states(bus, states) < 0) {
+ pci_bus_put(bus);
+ bus = NULL;
+ }
+
+ return bus;
+}
+EXPORT_SYMBOL(__pci_get_and_lock_bus);
+
+struct pci_bus *pci_lock_subordinate(struct pci_dev *dev, int states)
+{
+ struct pci_bus *bus = dev->subordinate;
+
+ if (bus && pci_bus_lock_states(bus, states) > 0)
+ return bus;
+
+ return NULL;
+}
+EXPORT_SYMBOL(pci_lock_subordinate);
+
+void pci_unlock_and_put_bus(struct pci_bus *bus)
+{
+ if (bus) {
+ pci_bus_unlock(bus);
+ pci_bus_put(bus);
+ }
+}
+EXPORT_SYMBOL(pci_unlock_and_put_bus);
+
EXPORT_SYMBOL(pci_bus_alloc_resource);
EXPORT_SYMBOL_GPL(pci_bus_add_device);
EXPORT_SYMBOL(pci_bus_add_devices);
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index f1147a7..c0a8a2b 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -69,6 +69,35 @@ static struct pci_bus *pci_do_find_bus(struct pci_bus *bus,
unsigned char busnr)
}
/**
+ * pci_get_bus - get 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
+ * in the global list of PCI buses. If the bus is found, a reference count
+ * is held on the returned PCI bus. If no bus is found, %NULL is returned.
+ */
+struct pci_bus *pci_get_bus(int domain, int busnr)
+{
+ struct pci_bus *bus;
+ struct pci_bus *tmp_bus = NULL;
+
+ down_read(&pci_bus_sem);
+ list_for_each_entry(bus, &pci_root_buses, node)
+ if (pci_domain_nr(bus) == domain) {
+ tmp_bus = pci_do_find_bus(bus, busnr);
+ if (tmp_bus) {
+ pci_bus_get(tmp_bus);
+ break;
+ }
+ }
+ up_read(&pci_bus_sem);
+
+ return tmp_bus;
+}
+EXPORT_SYMBOL(pci_get_bus);
+
+/**
* pci_find_bus - locate PCI bus from a given domain and bus number
* @domain: number of PCI domain to search
* @busnr: number of desired PCI bus
@@ -79,17 +108,12 @@ static struct pci_bus *pci_do_find_bus(struct pci_bus
*bus, unsigned char 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;
}
/**
diff --git a/include/linux/pci.h b/include/linux/pci.h
index e2ef517..9e52e88 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -488,6 +488,15 @@ extern int pci_bus_lock_states(struct pci_bus *bus, int
states);
extern void pci_bus_unlock(struct pci_bus *bus);
extern void pci_bus_change_state(struct pci_bus *bus, int new, int old,
bool unlock);
+extern struct pci_bus *pci_lock_subordinate(struct pci_dev *dev, int states);
+extern struct pci_bus *__pci_get_and_lock_bus(int domain, int busnr,
+ int states);
+extern void pci_unlock_and_put_bus(struct pci_bus *bus);
+
+static inline struct pci_bus *pci_get_and_lock_bus(int domain, int busnr)
+{
+ return __pci_get_and_lock_bus(domain, busnr, PCI_BUS_STATE_WORKING);
+}
#define pci_bus_b(n) list_entry(n, struct pci_bus, node)
#define to_pci_bus(n) container_of(n, struct pci_bus, dev)
@@ -734,6 +743,7 @@ void pcibios_bus_to_resource(struct pci_dev *dev, struct
resource *res,
struct pci_bus_region *region);
void pcibios_scan_specific_bus(int busn);
extern struct pci_bus *pci_find_bus(int domain, int busnr);
+struct pci_bus *pci_get_bus(int domain, int busnr);
void pci_bus_add_devices(const struct pci_bus *bus);
struct pci_bus *pci_scan_bus_parented(struct device *parent, int bus,
struct pci_ops *ops, void *sysdata);
--
1.7.9.5
--
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