linux-kernel - [PATCH 9/11] ACPI / hotplug / PCI: Simplify disable

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Message-ID: <3181996.2TszSTpj8L@vostro.rjw.lan>
Date:	Mon, 27 Jan 2014 01:44:46 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>, Aaron Lu <aaron.lu@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH 9/11] ACPI / hotplug / PCI: Simplify disable_slot()

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

After recent PCI core changes related to the rescan/remove locking,
the ACPIPHP's disable_slot() function is only called under the
general PCI rescan/remove lock, so it doesn't have to use
dev_in_slot() any more to avoid race conditions.  Make it simply
walk the devices on the bus and remove the ones in the slot being
disabled.  Then, drop dev_in_slot() which has no more users.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/pci/hotplug/acpiphp_glue.c |   28 +++++-----------------------
 1 file changed, 5 insertions(+), 23 deletions(-)

Index: linux-pm/drivers/pci/hotplug/acpiphp_glue.c
===================================================================
--- linux-pm.orig/drivers/pci/hotplug/acpiphp_glue.c
+++ linux-pm/drivers/pci/hotplug/acpiphp_glue.c
@@ -579,32 +579,15 @@ static void __ref enable_slot(struct acp
 	}
 }
 
-/* return first device in slot, acquiring a reference on it */
-static struct pci_dev *dev_in_slot(struct acpiphp_slot *slot)
-{
-	struct pci_bus *bus = slot->bus;
-	struct pci_dev *dev;
-	struct pci_dev *ret = NULL;
-
-	down_read(&pci_bus_sem);
-	list_for_each_entry(dev, &bus->devices, bus_list)
-		if (PCI_SLOT(dev->devfn) == slot->device) {
-			ret = pci_dev_get(dev);
-			break;
-		}
-	up_read(&pci_bus_sem);
-
-	return ret;
-}
-
 /**
  * disable_slot - disable a slot
  * @slot: ACPI PHP slot
  */
 static void disable_slot(struct acpiphp_slot *slot)
 {
+	struct pci_bus *bus = slot->bus;
+	struct pci_dev *dev, *next;
 	struct acpiphp_func *func;
-	struct pci_dev *pdev;
 
 	/*
 	 * enable_slot() enumerates all functions in this device via
@@ -612,10 +595,9 @@ static void disable_slot(struct acpiphp_
 	 * methods (_EJ0, etc.) or not.  Therefore, we remove all functions
 	 * here.
 	 */
-	while ((pdev = dev_in_slot(slot))) {
-		pci_stop_and_remove_bus_device(pdev);
-		pci_dev_put(pdev);
-	}
+	list_for_each_entry_safe(dev, next, &bus->devices, bus_list)
+		if (PCI_SLOT(dev->devfn) == slot->device)
+			pci_stop_and_remove_bus_device(dev);
 
 	list_for_each_entry(func, &slot->funcs, sibling)
 		acpi_bus_trim(func_to_acpi_device(func));

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