Patchwork [RFC,v1,15/22] PCI/eeepc: use PCI bus lock to avoid race conditions

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Submitter Jiang Liu
Date Aug. 7, 2012, 4:10 p.m.
Message ID <1344355862-2726-16-git-send-email-jiang.liu@huawei.com>
Download mbox | patch
Permalink /patch/175709/
State Not Applicable
Headers show

Comments

Jiang Liu - Aug. 7, 2012, 4:10 p.m.
This patch uses PCI bus lock mechanism to avoid race conditions when doing
PCI device hotplug through eeepc driver. It also fixes a PCI device reference
count leakage issue because acpi_get_pci_dev() holds a reference to the
device returned.

Signed-off-by: Jiang Liu <liuj97@gmail.com>
---
 drivers/platform/x86/eeepc-laptop.c |   20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)
Bjorn Helgaas - Sept. 11, 2012, 11:18 p.m.
On Tue, Aug 7, 2012 at 10:10 AM, Jiang Liu <liuj97@gmail.com> wrote:
> This patch uses PCI bus lock mechanism to avoid race conditions when doing
> PCI device hotplug through eeepc driver.

> It also fixes a PCI device reference
> count leakage issue because acpi_get_pci_dev() holds a reference to the
> device returned.

Can you split this refcount fix out as a separate patch?  That looks
pretty straightforward, unlike the bus lock stuff.

> Signed-off-by: Jiang Liu <liuj97@gmail.com>
> ---
>  drivers/platform/x86/eeepc-laptop.c |   20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
> index dab91b4..25c4176 100644
> --- a/drivers/platform/x86/eeepc-laptop.c
> +++ b/drivers/platform/x86/eeepc-laptop.c
> @@ -606,16 +606,16 @@ static void eeepc_rfkill_hotplug(struct eeepc_laptop *eeepc, acpi_handle handle)
>                         goto out_unlock;
>                 }
>
> -               bus = port->subordinate;
> +               bus = pci_lock_subordinate(port, PCI_BUS_STATE_WORKING);
>
>                 if (!bus) {
>                         pr_warn("Unable to find PCI bus 1?\n");
> -                       goto out_unlock;
> +                       goto out_put_dev;
>                 }
>
>                 if (pci_bus_read_config_dword(bus, 0, PCI_VENDOR_ID, &l)) {
>                         pr_err("Unable to read PCI config space?\n");
> -                       goto out_unlock;
> +                       goto out_unlock_bus;
>                 }
>
>                 absent = (l == 0xffffffff);
> @@ -627,7 +627,7 @@ static void eeepc_rfkill_hotplug(struct eeepc_laptop *eeepc, acpi_handle handle)
>                                 absent ? "absent" : "present");
>                         pr_warn("skipped wireless hotplug as probably "
>                                 "inappropriate for this model\n");
> -                       goto out_unlock;
> +                       goto out_unlock_bus;
>                 }
>
>                 if (!blocked) {
> @@ -635,7 +635,7 @@ static void eeepc_rfkill_hotplug(struct eeepc_laptop *eeepc, acpi_handle handle)
>                         if (dev) {
>                                 /* Device already present */
>                                 pci_dev_put(dev);
> -                               goto out_unlock;
> +                               goto out_unlock_bus;
>                         }
>                         dev = pci_scan_single_device(bus, 0);
>                         if (dev) {
> @@ -650,6 +650,11 @@ static void eeepc_rfkill_hotplug(struct eeepc_laptop *eeepc, acpi_handle handle)
>                                 pci_dev_put(dev);
>                         }
>                 }
> +
> +out_unlock_bus:
> +               pci_bus_unlock(bus);
> +out_put_dev:
> +               pci_dev_put(port);
>         }
>
>  out_unlock:
> @@ -757,7 +762,7 @@ static struct hotplug_slot_ops eeepc_hotplug_slot_ops = {
>  static int eeepc_setup_pci_hotplug(struct eeepc_laptop *eeepc)
>  {
>         int ret = -ENOMEM;
> -       struct pci_bus *bus = pci_find_bus(0, 1);
> +       struct pci_bus *bus = pci_get_bus(0, 1);
>
>         if (!bus) {
>                 pr_err("Unable to find wifi PCI bus\n");
> @@ -785,6 +790,8 @@ static int eeepc_setup_pci_hotplug(struct eeepc_laptop *eeepc)
>                 goto error_register;
>         }
>
> +       pci_bus_put(bus);
> +
>         return 0;
>
>  error_register:
> @@ -793,6 +800,7 @@ error_info:
>         kfree(eeepc->hotplug_slot);
>         eeepc->hotplug_slot = NULL;
>  error_slot:
> +       pci_bus_put(bus);
>         return ret;
>  }
>
> --
> 1.7.9.5
>
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Patch

diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
index dab91b4..25c4176 100644
--- a/drivers/platform/x86/eeepc-laptop.c
+++ b/drivers/platform/x86/eeepc-laptop.c
@@ -606,16 +606,16 @@  static void eeepc_rfkill_hotplug(struct eeepc_laptop *eeepc, acpi_handle handle)
 			goto out_unlock;
 		}
 
-		bus = port->subordinate;
+		bus = pci_lock_subordinate(port, PCI_BUS_STATE_WORKING);
 
 		if (!bus) {
 			pr_warn("Unable to find PCI bus 1?\n");
-			goto out_unlock;
+			goto out_put_dev;
 		}
 
 		if (pci_bus_read_config_dword(bus, 0, PCI_VENDOR_ID, &l)) {
 			pr_err("Unable to read PCI config space?\n");
-			goto out_unlock;
+			goto out_unlock_bus;
 		}
 
 		absent = (l == 0xffffffff);
@@ -627,7 +627,7 @@  static void eeepc_rfkill_hotplug(struct eeepc_laptop *eeepc, acpi_handle handle)
 				absent ? "absent" : "present");
 			pr_warn("skipped wireless hotplug as probably "
 				"inappropriate for this model\n");
-			goto out_unlock;
+			goto out_unlock_bus;
 		}
 
 		if (!blocked) {
@@ -635,7 +635,7 @@  static void eeepc_rfkill_hotplug(struct eeepc_laptop *eeepc, acpi_handle handle)
 			if (dev) {
 				/* Device already present */
 				pci_dev_put(dev);
-				goto out_unlock;
+				goto out_unlock_bus;
 			}
 			dev = pci_scan_single_device(bus, 0);
 			if (dev) {
@@ -650,6 +650,11 @@  static void eeepc_rfkill_hotplug(struct eeepc_laptop *eeepc, acpi_handle handle)
 				pci_dev_put(dev);
 			}
 		}
+
+out_unlock_bus:
+		pci_bus_unlock(bus);
+out_put_dev:
+		pci_dev_put(port);
 	}
 
 out_unlock:
@@ -757,7 +762,7 @@  static struct hotplug_slot_ops eeepc_hotplug_slot_ops = {
 static int eeepc_setup_pci_hotplug(struct eeepc_laptop *eeepc)
 {
 	int ret = -ENOMEM;
-	struct pci_bus *bus = pci_find_bus(0, 1);
+	struct pci_bus *bus = pci_get_bus(0, 1);
 
 	if (!bus) {
 		pr_err("Unable to find wifi PCI bus\n");
@@ -785,6 +790,8 @@  static int eeepc_setup_pci_hotplug(struct eeepc_laptop *eeepc)
 		goto error_register;
 	}
 
+	pci_bus_put(bus);
+
 	return 0;
 
 error_register:
@@ -793,6 +800,7 @@  error_info:
 	kfree(eeepc->hotplug_slot);
 	eeepc->hotplug_slot = NULL;
 error_slot:
+	pci_bus_put(bus);
 	return ret;
 }