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Date: Thu, 13 Jun 2013 21:59:44 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Jiang Liu <jiang.liu@...wei.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Yinghai Lu <yinghai@...nel.org>,
"Alexander E . Patrakov" <patrakov@...il.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Yijing Wang <wangyijing@...wei.com>,
Jiang Liu <liuj97@...il.com>, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
stable@...r.kernel.org
Subject: Re: [BUGFIX 2/9] ACPIPHP: fix device destroying order issue when handling dock notification
On Friday, June 14, 2013 12:32:25 AM Jiang Liu wrote:
> Current ACPI glue logic expects that physical devices are destroyed
> before destroying companion ACPI devices, otherwise it will break the
> ACPI unbind logic and cause following warning messages:
> [ 185.026073] usb usb5: Oops, 'acpi_handle' corrupt
> [ 185.035150] pci 0000:1b:00.0: Oops, 'acpi_handle' corrupt
> [ 185.035515] pci 0000:18:02.0: Oops, 'acpi_handle' corrupt
> [ 180.013656] port1: Oops, 'acpi_handle' corrupt
> Please refer to https://bugzilla.kernel.org/attachment.cgi?id=104321
> for full log message.
So my question is, did we have this problem before commit 3b63aaa70e1?
If we did, then when did it start? Or was it present forever?
> Above warning messages are caused by following scenario:
> 1) acpi_dock_notifier_call() queues a task (T1) onto kacpi_hotplug_wq
> 2) kacpi_hotplug_wq handles T1, which invokes acpi_dock_deferred_cb()
> ->dock_notify()-> handle_eject_request()->hotplug_dock_devices()
> 3) hotplug_dock_devices() first invokes registered hotplug callbacks to
> destroy physical devices, then destroys all affected ACPI devices.
> Everything seems perfect until now. But the acpiphp dock notification
> handler will queue another task (T2) onto kacpi_hotplug_wq to really
> destroy affected physical devices.
Would not the solution be to modify it so that it didn't spawn the other
task (T2), but removed the affected physical devices synchronously?
> 4) kacpi_hotplug_wq finishes T1, and all affected ACPI devices have
> been destroyed.
> 5) kacpi_hotplug_wq handles T2, which destroys all affected physical
> devices.
>
> So it breaks ACPI glue logic's expection because ACPI devices are destroyed
> in step 3 and physical devices are destroyed in step 5.
>
> Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
> Reported-by: Alexander E. Patrakov <patrakov@...il.com>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Yinghai Lu <yinghai@...nel.org>
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
> Cc: linux-pci@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: stable@...r.kernel.org
> ---
> Hi Bjorn and Rafael,
> The recursive lock changes haven't been tested yet, need help
> from Alexander for testing.
Well, let's just say I'm not a fan of recursive locks. Is that unavoidable
here?
Rafael
> ---
> drivers/acpi/dock.c | 33 +++++++++++++++++++++++++++------
> drivers/pci/hotplug/acpiphp_glue.c | 32 ++++++++++++++++++--------------
> 2 files changed, 45 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/acpi/dock.c b/drivers/acpi/dock.c
> index 02b0563..79c8d9e 100644
> --- a/drivers/acpi/dock.c
> +++ b/drivers/acpi/dock.c
> @@ -65,6 +65,7 @@ struct dock_station {
> u32 flags;
> spinlock_t dd_lock;
> struct mutex hp_lock;
> + struct task_struct *owner;
> struct list_head dependent_devices;
> struct list_head hotplug_devices;
>
> @@ -131,9 +132,13 @@ static void
> dock_add_hotplug_device(struct dock_station *ds,
> struct dock_dependent_device *dd)
> {
> - mutex_lock(&ds->hp_lock);
> - list_add_tail(&dd->hotplug_list, &ds->hotplug_devices);
> - mutex_unlock(&ds->hp_lock);
> + if (mutex_is_locked(&ds->hp_lock) && ds->owner == current) {
> + list_add_tail(&dd->hotplug_list, &ds->hotplug_devices);
> + } else {
> + mutex_lock(&ds->hp_lock);
> + list_add_tail(&dd->hotplug_list, &ds->hotplug_devices);
> + mutex_unlock(&ds->hp_lock);
> + }
> }
>
> /**
> @@ -147,9 +152,13 @@ static void
> dock_del_hotplug_device(struct dock_station *ds,
> struct dock_dependent_device *dd)
> {
> - mutex_lock(&ds->hp_lock);
> - list_del(&dd->hotplug_list);
> - mutex_unlock(&ds->hp_lock);
> + if (mutex_is_locked(&ds->hp_lock) && ds->owner == current) {
> + list_del_init(&dd->hotplug_list);
> + } else {
> + mutex_lock(&ds->hp_lock);
> + list_del_init(&dd->hotplug_list);
> + mutex_unlock(&ds->hp_lock);
> + }
> }
>
> /**
> @@ -355,7 +364,17 @@ static void hotplug_dock_devices(struct dock_station *ds, u32 event)
> {
> struct dock_dependent_device *dd;
>
> + /*
> + * There is a deadlock scenario as below:
> + * hotplug_dock_devices()
> + * mutex_lock(&ds->hp_lock)
> + * dd->ops->handler()
> + * register_hotplug_dock_device()
> + * mutex_lock(&ds->hp_lock)
> + * So we need recursive lock scematics here, do it by ourselves.
> + */
> mutex_lock(&ds->hp_lock);
> + ds->owner = current;
>
> /*
> * First call driver specific hotplug functions
> @@ -376,6 +395,8 @@ static void hotplug_dock_devices(struct dock_station *ds, u32 event)
> else
> dock_create_acpi_device(dd->handle);
> }
> +
> + ds->owner = NULL;
> mutex_unlock(&ds->hp_lock);
> }
>
> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> index 716aa93..699b8ca 100644
> --- a/drivers/pci/hotplug/acpiphp_glue.c
> +++ b/drivers/pci/hotplug/acpiphp_glue.c
> @@ -61,6 +61,8 @@ static DEFINE_MUTEX(bridge_mutex);
> static void handle_hotplug_event_bridge (acpi_handle, u32, void *);
> static void acpiphp_sanitize_bus(struct pci_bus *bus);
> static void acpiphp_set_hpp_values(struct pci_bus *bus);
> +static void _handle_hotplug_event_func(acpi_handle handle, u32 type,
> + void *context);
> static void handle_hotplug_event_func(acpi_handle handle, u32 type, void *context);
> static void free_bridge(struct kref *kref);
>
> @@ -147,7 +149,7 @@ static int post_dock_fixups(struct notifier_block *nb, unsigned long val,
>
>
> static const struct acpi_dock_ops acpiphp_dock_ops = {
> - .handler = handle_hotplug_event_func,
> + .handler = _handle_hotplug_event_func,
> };
>
> /* Check whether the PCI device is managed by native PCIe hotplug driver */
> @@ -1065,22 +1067,13 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type,
> alloc_acpi_hp_work(handle, type, context, _handle_hotplug_event_bridge);
> }
>
> -static void _handle_hotplug_event_func(struct work_struct *work)
> +static void _handle_hotplug_event_func(acpi_handle handle, u32 type,
> + void *context)
> {
> - struct acpiphp_func *func;
> + struct acpiphp_func *func = context;
> char objname[64];
> struct acpi_buffer buffer = { .length = sizeof(objname),
> .pointer = objname };
> - struct acpi_hp_work *hp_work;
> - acpi_handle handle;
> - u32 type;
> -
> - hp_work = container_of(work, struct acpi_hp_work, work);
> - handle = hp_work->handle;
> - type = hp_work->type;
> - func = (struct acpiphp_func *)hp_work->context;
> -
> - acpi_scan_lock_acquire();
>
> acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
>
> @@ -1113,7 +1106,18 @@ static void _handle_hotplug_event_func(struct work_struct *work)
> warn("notify_handler: unknown event type 0x%x for %s\n", type, objname);
> break;
> }
> +}
> +
> +static void _handle_hotplug_event_cb(struct work_struct *work)
> +{
> + struct acpiphp_func *func;
> + struct acpi_hp_work *hp_work;
>
> + hp_work = container_of(work, struct acpi_hp_work, work);
> + func = (struct acpiphp_func *)hp_work->context;
> + acpi_scan_lock_acquire();
> + _handle_hotplug_event_func(hp_work->handle, hp_work->type,
> + hp_work->context);
> acpi_scan_lock_release();
> kfree(hp_work); /* allocated in handle_hotplug_event_func */
> put_bridge(func->slot->bridge);
> @@ -1141,7 +1145,7 @@ static void handle_hotplug_event_func(acpi_handle handle, u32 type,
> * don't deadlock on hotplug actions.
> */
> get_bridge(func->slot->bridge);
> - alloc_acpi_hp_work(handle, type, context, _handle_hotplug_event_func);
> + alloc_acpi_hp_work(handle, type, context, _handle_hotplug_event_cb);
> }
>
> /*
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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