PCI: hotplug: Use global PCI rescan-remove locking

Multiple race conditions are possible between PCI hotplug and the generic
PCI bus rescan and device removal that can be triggered via sysfs.

To avoid those race conditions make PCI hotplug use global PCI
rescan-remove locking.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/hotplug/cpci_hotplug_pci.c

@@ -254,9 +254,12 @@ int __ref cpci_configure_slot(struct slot *slot)
 {
 	struct pci_dev *dev;
 	struct pci_bus *parent;
+	int ret = 0;
 
 	dbg("%s - enter", __func__);
 
+	pci_lock_rescan_remove();
+
 	if (slot->dev == NULL) {
 		dbg("pci_dev null, finding %02x:%02x:%x",
 		    slot->bus->number, PCI_SLOT(slot->devfn), PCI_FUNC(slot->devfn));
@@ -277,7 +280,8 @@ int __ref cpci_configure_slot(struct slot *slot)
 		slot->dev = pci_get_slot(slot->bus, slot->devfn);
 		if (slot->dev == NULL) {
 			err("Could not find PCI device for slot %02x", slot->number);
-			return -ENODEV;
+			ret = -ENODEV;
+			goto out;
 		}
 	}
 	parent = slot->dev->bus;
@@ -294,8 +298,10 @@ int __ref cpci_configure_slot(struct slot *slot)
 
 	pci_bus_add_devices(parent);
 
+ out:
+	pci_unlock_rescan_remove();
 	dbg("%s - exit", __func__);
-	return 0;
+	return ret;
 }
 
 int cpci_unconfigure_slot(struct slot* slot)
@@ -308,6 +314,8 @@ int cpci_unconfigure_slot(struct slot* slot)
 		return -ENODEV;
 	}
 
+	pci_lock_rescan_remove();
+
 	list_for_each_entry_safe(dev, temp, &slot->bus->devices, bus_list) {
 		if (PCI_SLOT(dev->devfn) != PCI_SLOT(slot->devfn))
 			continue;
@@ -318,6 +326,8 @@ int cpci_unconfigure_slot(struct slot* slot)
 	pci_dev_put(slot->dev);
 	slot->dev = NULL;
 
+	pci_unlock_rescan_remove();
+
 	dbg("%s - exit", __func__);
 	return 0;
 }

drivers/pci/hotplug/cpqphp_pci.c

@@ -86,6 +86,8 @@ int cpqhp_configure_device (struct controller* ctrl, struct pci_func* func)
 	struct pci_bus *child;
 	int num;
 
+	pci_lock_rescan_remove();
+
 	if (func->pci_dev == NULL)
 		func->pci_dev = pci_get_bus_and_slot(func->bus,PCI_DEVFN(func->device, func->function));
 
@@ -100,7 +102,7 @@ int cpqhp_configure_device (struct controller* ctrl, struct pci_func* func)
 		func->pci_dev = pci_get_bus_and_slot(func->bus, PCI_DEVFN(func->device, func->function));
 		if (func->pci_dev == NULL) {
 			dbg("ERROR: pci_dev still null\n");
-			return 0;
+			goto out;
 		}
 	}
 
@@ -113,6 +115,8 @@ int cpqhp_configure_device (struct controller* ctrl, struct pci_func* func)
 
 	pci_dev_put(func->pci_dev);
 
+ out:
+	pci_unlock_rescan_remove();
 	return 0;
 }
 
@@ -123,13 +127,15 @@ int cpqhp_unconfigure_device(struct pci_func* func)
 
 	dbg("%s: bus/dev/func = %x/%x/%x\n", __func__, func->bus, func->device, func->function);
 
+	pci_lock_rescan_remove();
 	for (j=0; j<8 ; j++) {
 		struct pci_dev* temp = pci_get_bus_and_slot(func->bus, PCI_DEVFN(func->device, j));
 		if (temp) {
 			pci_dev_put(temp);
 			pci_stop_and_remove_bus_device(temp);
 		}
 	}
+	pci_unlock_rescan_remove();
 	return 0;
 }
 

drivers/pci/hotplug/ibmphp_core.c

@@ -718,14 +718,19 @@ static void ibm_unconfigure_device(struct pci_func *func)
 					func->device, func->function);
 	debug("func->device << 3 | 0x0  = %x\n", func->device << 3 | 0x0);
 
+	pci_lock_rescan_remove();
+
 	for (j = 0; j < 0x08; j++) {
 		temp = pci_get_bus_and_slot(func->busno, (func->device << 3) | j);
 		if (temp) {
 			pci_stop_and_remove_bus_device(temp);
 			pci_dev_put(temp);
 		}
 	}
+
 	pci_dev_put(func->dev);
+
+	pci_unlock_rescan_remove();
 }
 
 /*
@@ -780,6 +785,8 @@ static int ibm_configure_device(struct pci_func *func)
 	int flag = 0;	/* this is to make sure we don't double scan the bus,
 					for bridged devices primarily */
 
+	pci_lock_rescan_remove();
+
 	if (!(bus_structure_fixup(func->busno)))
 		flag = 1;
 	if (func->dev == NULL)
@@ -789,7 +796,7 @@ static int ibm_configure_device(struct pci_func *func)
 	if (func->dev == NULL) {
 		struct pci_bus *bus = pci_find_bus(0, func->busno);
 		if (!bus)
-			return 0;
+			goto out;
 
 		num = pci_scan_slot(bus,
 				PCI_DEVFN(func->device, func->function));
@@ -800,7 +807,7 @@ static int ibm_configure_device(struct pci_func *func)
 				PCI_DEVFN(func->device, func->function));
 		if (func->dev == NULL) {
 			err("ERROR... : pci_dev still NULL\n");
-			return 0;
+			goto out;
 		}
 	}
 	if (!(flag) && (func->dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)) {
@@ -810,6 +817,8 @@ static int ibm_configure_device(struct pci_func *func)
 			pci_bus_add_devices(child);
 	}
 
+ out:
+	pci_unlock_rescan_remove();
 	return 0;
 }
 

drivers/pci/hotplug/pciehp_pci.c

@@ -39,22 +39,26 @@ int pciehp_configure_device(struct slot *p_slot)
 	struct pci_dev *dev;
 	struct pci_dev *bridge = p_slot->ctrl->pcie->port;
 	struct pci_bus *parent = bridge->subordinate;
-	int num;
+	int num, ret = 0;
 	struct controller *ctrl = p_slot->ctrl;
 
+	pci_lock_rescan_remove();
+
 	dev = pci_get_slot(parent, PCI_DEVFN(0, 0));
 	if (dev) {
 		ctrl_err(ctrl, "Device %s already exists "
 			 "at %04x:%02x:00, cannot hot-add\n", pci_name(dev),
 			 pci_domain_nr(parent), parent->number);
 		pci_dev_put(dev);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 
 	num = pci_scan_slot(parent, PCI_DEVFN(0, 0));
 	if (num == 0) {
 		ctrl_err(ctrl, "No new device found\n");
-		return -ENODEV;
+		ret = -ENODEV;
+		goto out;
 	}
 
 	list_for_each_entry(dev, &parent->devices, bus_list)
@@ -73,7 +77,9 @@ int pciehp_configure_device(struct slot *p_slot)
 
 	pci_bus_add_devices(parent);
 
-	return 0;
+ out:
+	pci_unlock_rescan_remove();
+	return ret;
 }
 
 int pciehp_unconfigure_device(struct slot *p_slot)
@@ -90,6 +96,8 @@ int pciehp_unconfigure_device(struct slot *p_slot)
 		 __func__, pci_domain_nr(parent), parent->number);
 	pciehp_get_adapter_status(p_slot, &presence);
 
+	pci_lock_rescan_remove();
+
 	/*
 	 * Stopping an SR-IOV PF device removes all the associated VFs,
 	 * which will update the bus->devices list and confuse the
@@ -124,5 +132,6 @@ int pciehp_unconfigure_device(struct slot *p_slot)
 		pci_dev_put(dev);
 	}
 
+	pci_unlock_rescan_remove();
 	return rc;
 }

drivers/pci/hotplug/rpadlpar_core.c

@@ -354,10 +354,15 @@ int dlpar_remove_pci_slot(char *drc_name, struct device_node *dn)
 {
 	struct pci_bus *bus;
 	struct slot *slot;
+	int ret = 0;
+
+	pci_lock_rescan_remove();
 
 	bus = pcibios_find_pci_bus(dn);
-	if (!bus)
-		return -EINVAL;
+	if (!bus) {
+		ret = -EINVAL;
+		goto out;
+	}
 
 	pr_debug("PCI: Removing PCI slot below EADS bridge %s\n",
 		 bus->self ? pci_name(bus->self) : "<!PHB!>");
@@ -371,7 +376,8 @@ int dlpar_remove_pci_slot(char *drc_name, struct device_node *dn)
 			printk(KERN_ERR
 				"%s: unable to remove hotplug slot %s\n",
 				__func__, drc_name);
-			return -EIO;
+			ret = -EIO;
+			goto out;
 		}
 	}
 
@@ -382,15 +388,18 @@ int dlpar_remove_pci_slot(char *drc_name, struct device_node *dn)
 	if (pcibios_unmap_io_space(bus)) {
 		printk(KERN_ERR "%s: failed to unmap bus range\n",
 			__func__);
-		return -ERANGE;
+		ret = -ERANGE;
+		goto out;
 	}
 
 	/* Remove the EADS bridge device itself */
 	BUG_ON(!bus->self);
 	pr_debug("PCI: Now removing bridge device %s\n", pci_name(bus->self));
 	pci_stop_and_remove_bus_device(bus->self);
 
-	return 0;
+ out:
+	pci_unlock_rescan_remove();
+	return ret;
 }
 
 /**

drivers/pci/hotplug/rpaphp_core.c

@@ -398,7 +398,9 @@ static int enable_slot(struct hotplug_slot *hotplug_slot)
 		return retval;
 
 	if (state == PRESENT) {
+		pci_lock_rescan_remove();
 		pcibios_add_pci_devices(slot->bus);
+		pci_unlock_rescan_remove();
 		slot->state = CONFIGURED;
 	} else if (state == EMPTY) {
 		slot->state = EMPTY;
@@ -418,7 +420,9 @@ static int disable_slot(struct hotplug_slot *hotplug_slot)
 	if (slot->state == NOT_CONFIGURED)
 		return -EINVAL;
 
+	pci_lock_rescan_remove();
 	pcibios_remove_pci_devices(slot->bus);
+	pci_unlock_rescan_remove();
 	vm_unmap_aliases();
 
 	slot->state = NOT_CONFIGURED;

drivers/pci/hotplug/s390_pci_hpc.c

@@ -80,7 +80,9 @@ static int enable_slot(struct hotplug_slot *hotplug_slot)
 		goto out_deconfigure;
 
 	pci_scan_slot(slot->zdev->bus, ZPCI_DEVFN);
+	pci_lock_rescan_remove();
 	pci_bus_add_devices(slot->zdev->bus);
+	pci_unlock_rescan_remove();
 
 	return rc;
 
@@ -98,7 +100,7 @@ static int disable_slot(struct hotplug_slot *hotplug_slot)
 		return -EIO;
 
 	if (slot->zdev->pdev)
-		pci_stop_and_remove_bus_device(slot->zdev->pdev);
+		pci_stop_and_remove_bus_device_locked(slot->zdev->pdev);
 
 	rc = zpci_disable_device(slot->zdev);
 	if (rc)

drivers/pci/hotplug/sgi_hotplug.c

@@ -459,12 +459,15 @@ static int enable_slot(struct hotplug_slot *bss_hotplug_slot)
 		acpi_scan_lock_release();
 	}
 
+	pci_lock_rescan_remove();
+
 	/* Call the driver for the new device */
 	pci_bus_add_devices(slot->pci_bus);
 	/* Call the drivers for the new devices subordinate to PPB */
 	if (new_ppb)
 		pci_bus_add_devices(new_bus);
 
+	pci_unlock_rescan_remove();
 	mutex_unlock(&sn_hotplug_mutex);
 
 	if (rc == 0)
@@ -540,6 +543,7 @@ static int disable_slot(struct hotplug_slot *bss_hotplug_slot)
 		acpi_scan_lock_release();
 	}
 
+	pci_lock_rescan_remove();
 	/* Free the SN resources assigned to the Linux device.*/
 	list_for_each_entry_safe(dev, temp, &slot->pci_bus->devices, bus_list) {
 		if (PCI_SLOT(dev->devfn) != slot->device_num + 1)
@@ -550,6 +554,7 @@ static int disable_slot(struct hotplug_slot *bss_hotplug_slot)
 		pci_stop_and_remove_bus_device(dev);
 		pci_dev_put(dev);
 	}
+	pci_unlock_rescan_remove();
 
 	/* Remove the SSDT for the slot from the ACPI namespace */
 	if (SN_ACPI_BASE_SUPPORT() && ssdt_id) {

drivers/pci/hotplug/shpchp_pci.c

@@ -40,21 +40,25 @@ int __ref shpchp_configure_device(struct slot *p_slot)
 	struct controller *ctrl = p_slot->ctrl;
 	struct pci_dev *bridge = ctrl->pci_dev;
 	struct pci_bus *parent = bridge->subordinate;
-	int num;
+	int num, ret = 0;
+
+	pci_lock_rescan_remove();
 
 	dev = pci_get_slot(parent, PCI_DEVFN(p_slot->device, 0));
 	if (dev) {
 		ctrl_err(ctrl, "Device %s already exists "
 			 "at %04x:%02x:%02x, cannot hot-add\n", pci_name(dev),
 			 pci_domain_nr(parent), p_slot->bus, p_slot->device);
 		pci_dev_put(dev);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 
 	num = pci_scan_slot(parent, PCI_DEVFN(p_slot->device, 0));
 	if (num == 0) {
 		ctrl_err(ctrl, "No new device found\n");
-		return -ENODEV;
+		ret = -ENODEV;
+		goto out;
 	}
 
 	list_for_each_entry(dev, &parent->devices, bus_list) {
@@ -75,7 +79,9 @@ int __ref shpchp_configure_device(struct slot *p_slot)
 
 	pci_bus_add_devices(parent);
 
-	return 0;
+ out:
+	pci_unlock_rescan_remove();
+	return ret;
 }
 
 int shpchp_unconfigure_device(struct slot *p_slot)
@@ -89,6 +95,8 @@ int shpchp_unconfigure_device(struct slot *p_slot)
 	ctrl_dbg(ctrl, "%s: domain:bus:dev = %04x:%02x:%02x\n",
 		 __func__, pci_domain_nr(parent), p_slot->bus, p_slot->device);
 
+	pci_lock_rescan_remove();
+
 	list_for_each_entry_safe(dev, temp, &parent->devices, bus_list) {
 		if (PCI_SLOT(dev->devfn) != p_slot->device)
 			continue;
@@ -108,6 +116,8 @@ int shpchp_unconfigure_device(struct slot *p_slot)
 		pci_stop_and_remove_bus_device(dev);
 		pci_dev_put(dev);
 	}
+
+	pci_unlock_rescan_remove();
 	return rc;
 }