Every new PCI bus will be created with the PCI_BUS_STATE_LOCK bit set,
so a typical PCI device hot-add flow is:
pci_bus_lock(parent, PCI_BUS_STATE_STARTED, true);
pci_scan_slot(parent, PCI_DEVFN(0, 0));
pci_bus_add_devices(parent);
pci_bus_unlock(parent, true); // recursively unlock all PCI
// buses, including new PCI buses
This patch also changes behaviors of interfaces to create PCI root buses:
pci_create_root_bus(): return with new PCI root bus locked
pci_scan_bus_parented(): return with new PCI root bus locked
pci_scan_root_bus(): return with new PCI root bus unlocked
pci_scan_bus(): return with new PCI root bus unlocked
pci_scan_bus_parented() has already been marked as __deprecated and
all in-tree callers have been converted to use other interfaces.
So following-on patches will enhance callers of pci_create_root_bus()
to unlock returned root buses.
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
drivers/pci/hotplug-pci.c | 4 ++++
drivers/pci/probe.c | 18 ++++++++++++++++++
2 files changed, 22 insertions(+)
diff --git a/drivers/pci/hotplug-pci.c b/drivers/pci/hotplug-pci.c
index 18533ed..8faa3c2 100644
--- a/drivers/pci/hotplug-pci.c
+++ b/drivers/pci/hotplug-pci.c
@@ -10,6 +10,10 @@ int __ref pci_hp_add_bridge(struct pci_dev *dev)
int pass, busnr, start = parent->busn_res.start;
int end = parent->busn_res.end;
+ BUG_ON(!pci_bus_is_locked(parent));
+ if (pci_bus_get_state(parent) > PCI_BUS_STATE_STARTED)
+ return 0;
+
for (busnr = start; busnr <= end; busnr++) {
if (!pci_bus_exists(pci_domain_nr(parent), busnr))
break;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 9fcf3a3..0ddf5b8 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -745,6 +745,10 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
u8 primary, secondary, subordinate;
int broken = 0;
+ BUG_ON(!pci_bus_is_locked(bus));
+ if (pci_bus_get_state(bus) > PCI_BUS_STATE_STARTED)
+ return max;
+
pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
primary = buses & 0xFF;
secondary = (buses >> 8) & 0xFF;
@@ -799,6 +803,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
pci_bus_insert_busn_res(child, secondary, subordinate);
child->bridge_ctl = bctl;
pci_bus_get(child);
+ } else {
+ BUG_ON(!pci_bus_is_locked(child));
}
cmax = pci_scan_child_bus(child);
@@ -837,6 +843,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
goto out;
pci_bus_insert_busn_res(child, max, 0xff);
pci_bus_get(child);
+ } else {
+ BUG_ON(!pci_bus_is_locked(child));
}
buses = (buses & 0xff000000)
| ((unsigned int)(child->primary) << 0)
@@ -1322,6 +1330,7 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
{
int ret;
+ BUG_ON(!pci_bus_is_locked(bus));
device_initialize(&dev->dev);
dev->dev.release = pci_release_dev;
@@ -1369,6 +1378,10 @@ struct pci_dev *__ref pci_scan_single_device(struct pci_bus *bus, int devfn)
{
struct pci_dev *dev;
+ BUG_ON(!pci_bus_is_locked(bus));
+ if (pci_bus_get_state(bus) > PCI_BUS_STATE_STARTED)
+ return NULL;
+
dev = pci_get_slot(bus, devfn);
if (dev) {
pci_dev_put(dev);
@@ -1624,6 +1637,8 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus)
unsigned int devfn, pass, max = bus->busn_res.start;
struct pci_dev *dev;
+ BUG_ON(!pci_bus_is_locked(bus));
+ BUG_ON(pci_bus_get_state(bus) > PCI_BUS_STATE_STARTED);
dev_dbg(&bus->dev, "scanning bus\n");
/* Go find them, Rover! */
@@ -1872,6 +1887,8 @@ struct pci_bus *pci_scan_root_bus(struct device *parent, int bus,
pci_bus_update_busn_res_end(b, max);
pci_bus_add_devices(b);
+ pci_bus_unlock(b, true);
+
return b;
}
EXPORT_SYMBOL(pci_scan_root_bus);
@@ -1908,6 +1925,7 @@ struct pci_bus *pci_scan_bus(int bus, struct pci_ops *ops,
if (b) {
pci_scan_child_bus(b);
pci_bus_add_devices(b);
+ pci_bus_unlock(b, true);
} else {
pci_free_resource_list(&resources);
}
--
1.8.1.2
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