Re: [PATCH] eeepc-laptop: fix hot-unplug on resume

Rafael J. Wysocki
2009-06-29T14:16:56Z

On Monday 29 June 2009, Alan Jenkins wrote:
> The patch below fixes a regression introduced by the rfkill rewrite.
> Please consider it for inclusion in 2.6.31 via the ACPI tree.

Is there a Bugzilla # for this regression?

Rafael

> -------------------->
>
> From d0265f0bfe63086816d61c69ee4b2dc4cb491d06 Mon Sep 17 00:00:00 2001
> From: Alan Jenkins <alan-jenkins-cCz0Lq7MMjm9FHfhHBbuYA@public.gmane.org>
> Date: Mon, 29 Jun 2009 09:40:07 +0100
> Subject: [PATCH] eeepc-laptop: fix hot-unplug on resume
>
> OOPS on resume when the wireless adaptor is disabled during suspend was
> introduced by "eeepc-laptop: read rfkill soft-blocked state on resume".
>
> Unable to handle kernel NULL pointer dereference
>
> Process s2disk
> Tainted: G W
> IP: klist_put
>
> Call trace:
> ? klist_del
> ? device_del
> ? device_unregister
> ? pci_stop_dev
> ? pci_stop_bus
> ? pci_remove_device
> ? eeepc_rfkill_hotplug [eeepc_laptop]
> ? eeepc_hotk_resume [eeepc_laptop]
> ? acpi_device_resume
> ? device_resume
> ? hibernation_snapshot
>
> It appears the PCI device is removed twice. The eeepc_rfkill_hotplug()
> call from the resume handler is racing against the call from the ACPI
> notifier callback. The ACPI notification is triggered by the resume
> handler when it refreshes the value of CM_ASL_WLAN.
>
> The fix is to serialize hotplug calls using a workqueue.
>
> Signed-off-by: Alan Jenkins <alan-jenkins-cCz0Lq7MMjm9FHfhHBbuYA@public.gmane.org>
> ---
> drivers/platform/x86/eeepc-laptop.c | 9 ++++++---
> 1 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
> index ec560f1..222ffb8 100644
> --- a/drivers/platform/x86/eeepc-laptop.c
> +++ b/drivers/platform/x86/eeepc-laptop.c
> @@ -143,6 +143,7 @@ struct eeepc_hotk {
> struct rfkill *bluetooth_rfkill;
> struct rfkill *wwan3g_rfkill;
> struct hotplug_slot *hotplug_slot;
> + struct work_struct hotplug_work;
> };
>
> /* The actual device the driver binds to */
> @@ -660,7 +661,7 @@ static int eeepc_get_adapter_status(struct hotplug_slot *hotplug_slot,
> return 0;
> }
>
> -static void eeepc_rfkill_hotplug(void)
> +static void eeepc_hotplug_work(struct work_struct *work)
> {
> struct pci_dev *dev;
> struct pci_bus *bus = pci_find_bus(0, 1);
> @@ -701,7 +702,7 @@ static void eeepc_rfkill_notify(acpi_handle handle, u32 event, void *data)
> if (event != ACPI_NOTIFY_BUS_CHECK)
> return;
>
> - eeepc_rfkill_hotplug();
> + schedule_work(&ehotk->hotplug_work);
> }
>
> static void eeepc_hotk_notify(struct acpi_device *device, u32 event)
> @@ -892,7 +893,7 @@ static int eeepc_hotk_resume(struct acpi_device *device)
>
> rfkill_set_sw_state(ehotk->wlan_rfkill, wlan != 1);
>
> - eeepc_rfkill_hotplug();
> + schedule_work(&ehotk->hotplug_work);
> }
>
> if (ehotk->bluetooth_rfkill)
> @@ -1093,6 +1094,8 @@ static int eeepc_rfkill_init(struct device *dev)
> {
> int result = 0;
>
> + INIT_WORK(&ehotk->hotplug_work, eeepc_hotplug_work);
> +
> eeepc_register_rfkill_notifier("\\_SB.PCI0.P0P6");
> eeepc_register_rfkill_notifier("\\_SB.PCI0.P0P7");
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