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authorDavid Herrmann <dh.herrmann@gmail.com>2013-10-02 13:47:28 +0200
committerJiri Kosina <jkosina@suse.cz>2013-10-07 17:08:26 +0200
commitf50f9aabf32db7414551ffdfdccc71be5f3d6e7d (patch)
tree1d624ee07097e1548551f77dfa537cff6400619b /drivers/hid/hid-wiimote-modules.c
parent7da7cbbbeb60e0939fecdf9723b388136c175e5c (diff)
downloadlinux-f50f9aabf32db7414551ffdfdccc71be5f3d6e7d.tar.bz2
HID: wiimote: fix FF deadlock
The input core has an internal spinlock that is acquired during event injection via input_event() and friends but also held during FF callbacks. That means, there is no way to share a lock between event-injection and FF handling. Unfortunately, this is what is required for wiimote state tracking and what we do with state.lock and input->lock. This deadlock can be triggered when using continuous data reporting and FF on a wiimote device at the same time. I takes me at least 30m of stress-testing to trigger it but users reported considerably shorter times (http://bpaste.net/show/132504/) when using some gaming-console emulators. The real problem is that we have two copies of internal state, one in the wiimote objects and the other in the input device. As the input-lock is not supposed to be accessed from outside of input-core, we have no other chance than offloading FF handling into a worker. This actually works pretty nice and also allows to implictly merge fast rumble changes into a single request. Due to the 3-layered workers (rumble+queue+l2cap) this might reduce FF responsiveness. Initial tests were fine so lets fix the race first and if it turns out to be too slow we can always handle FF out-of-band and skip the queue-worker. Cc: <stable@vger.kernel.org> # 3.11+ Reported-by: Thomas Schneider Signed-off-by: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid/hid-wiimote-modules.c')
-rw-r--r--drivers/hid/hid-wiimote-modules.c40
1 files changed, 29 insertions, 11 deletions
diff --git a/drivers/hid/hid-wiimote-modules.c b/drivers/hid/hid-wiimote-modules.c
index 2e7d644dba18..71adf9e60b13 100644
--- a/drivers/hid/hid-wiimote-modules.c
+++ b/drivers/hid/hid-wiimote-modules.c
@@ -119,12 +119,22 @@ static const struct wiimod_ops wiimod_keys = {
* the rumble motor, this flag shouldn't be set.
*/
+/* used by wiimod_rumble and wiipro_rumble */
+static void wiimod_rumble_worker(struct work_struct *work)
+{
+ struct wiimote_data *wdata = container_of(work, struct wiimote_data,
+ rumble_worker);
+
+ spin_lock_irq(&wdata->state.lock);
+ wiiproto_req_rumble(wdata, wdata->state.cache_rumble);
+ spin_unlock_irq(&wdata->state.lock);
+}
+
static int wiimod_rumble_play(struct input_dev *dev, void *data,
struct ff_effect *eff)
{
struct wiimote_data *wdata = input_get_drvdata(dev);
__u8 value;
- unsigned long flags;
/*
* The wiimote supports only a single rumble motor so if any magnitude
@@ -137,9 +147,10 @@ static int wiimod_rumble_play(struct input_dev *dev, void *data,
else
value = 0;
- spin_lock_irqsave(&wdata->state.lock, flags);
- wiiproto_req_rumble(wdata, value);
- spin_unlock_irqrestore(&wdata->state.lock, flags);
+ /* Locking state.lock here might deadlock with input_event() calls.
+ * schedule_work acts as barrier. Merging multiple changes is fine. */
+ wdata->state.cache_rumble = value;
+ schedule_work(&wdata->rumble_worker);
return 0;
}
@@ -147,6 +158,8 @@ static int wiimod_rumble_play(struct input_dev *dev, void *data,
static int wiimod_rumble_probe(const struct wiimod_ops *ops,
struct wiimote_data *wdata)
{
+ INIT_WORK(&wdata->rumble_worker, wiimod_rumble_worker);
+
set_bit(FF_RUMBLE, wdata->input->ffbit);
if (input_ff_create_memless(wdata->input, NULL, wiimod_rumble_play))
return -ENOMEM;
@@ -159,6 +172,8 @@ static void wiimod_rumble_remove(const struct wiimod_ops *ops,
{
unsigned long flags;
+ cancel_work_sync(&wdata->rumble_worker);
+
spin_lock_irqsave(&wdata->state.lock, flags);
wiiproto_req_rumble(wdata, 0);
spin_unlock_irqrestore(&wdata->state.lock, flags);
@@ -1731,7 +1746,6 @@ static int wiimod_pro_play(struct input_dev *dev, void *data,
{
struct wiimote_data *wdata = input_get_drvdata(dev);
__u8 value;
- unsigned long flags;
/*
* The wiimote supports only a single rumble motor so if any magnitude
@@ -1744,9 +1758,10 @@ static int wiimod_pro_play(struct input_dev *dev, void *data,
else
value = 0;
- spin_lock_irqsave(&wdata->state.lock, flags);
- wiiproto_req_rumble(wdata, value);
- spin_unlock_irqrestore(&wdata->state.lock, flags);
+ /* Locking state.lock here might deadlock with input_event() calls.
+ * schedule_work acts as barrier. Merging multiple changes is fine. */
+ wdata->state.cache_rumble = value;
+ schedule_work(&wdata->rumble_worker);
return 0;
}
@@ -1756,6 +1771,8 @@ static int wiimod_pro_probe(const struct wiimod_ops *ops,
{
int ret, i;
+ INIT_WORK(&wdata->rumble_worker, wiimod_rumble_worker);
+
wdata->extension.input = input_allocate_device();
if (!wdata->extension.input)
return -ENOMEM;
@@ -1817,12 +1834,13 @@ static void wiimod_pro_remove(const struct wiimod_ops *ops,
if (!wdata->extension.input)
return;
+ input_unregister_device(wdata->extension.input);
+ wdata->extension.input = NULL;
+ cancel_work_sync(&wdata->rumble_worker);
+
spin_lock_irqsave(&wdata->state.lock, flags);
wiiproto_req_rumble(wdata, 0);
spin_unlock_irqrestore(&wdata->state.lock, flags);
-
- input_unregister_device(wdata->extension.input);
- wdata->extension.input = NULL;
}
static const struct wiimod_ops wiimod_pro = {