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@xxxxxxxxxxxxxxx> # 3.11+ Reported-by: Thomas Schneider Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx> --- drivers/hid/hid-wiimote-modules.c | 40 ++++++++++++++++++++++++++++----------- drivers/hid/hid-wiimote.h | 4 +++- 2 files changed, 32 insertions(+), 12 deletions(-) diff --git a/drivers/hid/hid-wiimote-modules.c b/drivers/hid/hid-wiimote-modules.c index 2e7d644..71adf9e 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 = { diff --git a/drivers/hid/hid-wiimote.h b/drivers/hid/hid-wiimote.h index f1474f3..75db0c4 100644 --- a/drivers/hid/hid-wiimote.h +++ b/drivers/hid/hid-wiimote.h @@ -133,13 +133,15 @@ struct wiimote_state { __u8 *cmd_read_buf; __u8 cmd_read_size; - /* calibration data */ + /* calibration/cache data */ __u16 calib_bboard[4][3]; + __u8 cache_rumble; }; struct wiimote_data { struct hid_device *hdev; struct input_dev *input; + struct work_struct rumble_worker; struct led_classdev *leds[4]; struct input_dev *accel; struct input_dev *ir; -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
