[RFC PATCH v2, part3 09/11] PCI, acpiphp: use PCI bus lock to protect PCI device hotplug

[Jiang Liu]

Use PCI bus lock to protect concurrent PCI device hotplug operations.

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
Cc: Yijing Wang <wangyijing@xxxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 drivers/pci/hotplug/acpiphp_glue.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index e330331..d105dcd 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -674,6 +674,9 @@ static int __ref enable_device(struct acpiphp_slot *slot)
 	if (slot->flags & SLOT_ENABLED)
 		goto err_exit;
 
+	if (pci_bus_lock(bus, PCI_BUS_STATE_STOPPING - 1, true) < 0)
+		goto err_exit;
+
 	list_for_each_entry(func, &slot->funcs, sibling)
 		acpiphp_bus_add(func);
 
@@ -681,7 +684,7 @@ static int __ref enable_device(struct acpiphp_slot *slot)
 	if (num == 0) {
 		/* Maybe only part of funcs are added. */
 		dbg("No new device found\n");
-		goto err_exit;
+		goto out_unlock;
 	}
 
 	max = acpiphp_max_busnr(bus);
@@ -726,8 +729,9 @@ static int __ref enable_device(struct acpiphp_slot *slot)
 		}
 	}
 
-
- err_exit:
+out_unlock:
+	pci_bus_unlock(bus, true);
+err_exit:
 	return 0;
 }
 
@@ -757,7 +761,10 @@ static int disable_device(struct acpiphp_slot *slot)
 {
 	struct acpiphp_func *func;
 	struct pci_dev *pdev;
+	struct pci_bus *bus = slot->bridge->pci_bus;
 
+	if (pci_bus_lock(bus, PCI_BUS_STATE_STOPPING - 1, true) < 0)
+		return -EBUSY;
 	/*
 	 * enable_device() enumerates all functions in this device via
 	 * pci_scan_slot(), whether they have associated ACPI hotplug
@@ -768,6 +775,7 @@ static int disable_device(struct acpiphp_slot *slot)
 		pci_stop_and_remove_bus_device(pdev);
 		pci_dev_put(pdev);
 	}
+	pci_bus_unlock(bus, true);
 
 	list_for_each_entry(func, &slot->funcs, sibling) {
 		acpiphp_bus_trim(func->handle);
-- 
1.8.1.2

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