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media: cec-pin.c: don't zero work_pin_num_events in adap_enable 

It's OK to keep the pending pin events when disabling or
enabling the 'adapter'. Zeroing this can cause a race condition
if this happens when the pin kthread is handling a pin event
and calls atomic_dec later, causing work_pin_num_events to become
negative.

Just leave pending events in the queue, they'll be read eventually.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
This commit is contained in:
Hans Verkuil 2022-05-10 13:59:48 +02:00 committed by Mauro Carvalho Chehab
parent 60965c6a19
commit 5f4eb16750
1 changed files with 1 additions and 4 deletions
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5
drivers/media/cec/core/cec-pin.c
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@ -1123,9 +1123,6 @@ static int cec_pin_adap_enable(struct cec_adapter *adap, bool enable)
struct cec_pin *pin = adap->pin;
if (enable) {
atomic_set(&pin->work_pin_num_events, 0);
pin->work_pin_events_rd = pin->work_pin_events_wr = 0;
pin->work_pin_events_dropped = false;
cec_pin_read(pin);
cec_pin_to_idle(pin);
pin->tx_msg.len = 0;
@ -1150,7 +1147,6 @@ static int cec_pin_adap_enable(struct cec_adapter *adap, bool enable)
cec_pin_to_idle(pin);
pin->state = CEC_ST_OFF;
pin->work_tx_status = 0;
atomic_set(&pin->work_pin_num_events, 0);
atomic_set(&pin->work_irq_change, CEC_PIN_IRQ_DISABLE);
wake_up_interruptible(&pin->kthread_waitq);
}
@ -1338,6 +1334,7 @@ struct cec_adapter *cec_pin_allocate_adapter(const struct cec_pin_ops *pin_ops,
return ERR_PTR(-ENOMEM);
pin->ops = pin_ops;
hrtimer_init(&pin->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
atomic_set(&pin->work_pin_num_events, 0);
pin->timer.function = cec_pin_timer;
init_waitqueue_head(&pin->kthread_waitq);
pin->tx_custom_low_usecs = CEC_TIM_CUSTOM_DEFAULT;