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media: cec-pin: fix interrupt en/disable handling 

The en/disable_irq() functions keep track of the 'depth': i.e. if
interrupts are disabled twice, then it needs to enable_irq() calls to
enable them again. The cec-pin framework didn't take this into accound
and could disable irqs multiple times, and it expected that a single
enable_irq() would enable them again.

Move all calls to en/disable_irq() to the kthread where it is easy
to keep track of the current irq state and ensure that multiple
en/disable_irq calls never happen.

If interrupts where disabled twice, then they would never turn on
again, leaving the CEC adapter in a dead state.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: 865463fc03 (media: cec-pin: add error injection support)
Cc: <stable@vger.kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Hans Verkuil 2021-12-01 13:41:25 +01:00 committed by Mauro Carvalho Chehab
parent 3a2e4b1936
commit 713bdfa10b
1 changed files with 18 additions and 13 deletions
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31
drivers/media/cec/core/cec-pin.c
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@ -1033,6 +1033,7 @@ static int cec_pin_thread_func(void *_adap)
{
struct cec_adapter *adap = _adap;
struct cec_pin *pin = adap->pin;
bool irq_enabled = false;
for (;;) {
wait_event_interruptible(pin->kthread_waitq,
@ -1060,6 +1061,7 @@ static int cec_pin_thread_func(void *_adap)
ns_to_ktime(pin->work_rx_msg.rx_ts));
msg->len = 0;
}
if (pin->work_tx_status) {
unsigned int tx_status = pin->work_tx_status;
@ -1083,27 +1085,39 @@ static int cec_pin_thread_func(void *_adap)
switch (atomic_xchg(&pin->work_irq_change,
CEC_PIN_IRQ_UNCHANGED)) {
case CEC_PIN_IRQ_DISABLE:
pin->ops->disable_irq(adap);
if (irq_enabled) {
pin->ops->disable_irq(adap);
irq_enabled = false;
}
cec_pin_high(pin);
cec_pin_to_idle(pin);
hrtimer_start(&pin->timer, ns_to_ktime(0),
HRTIMER_MODE_REL);
break;
case CEC_PIN_IRQ_ENABLE:
if (irq_enabled)
break;
pin->enable_irq_failed = !pin->ops->enable_irq(adap);
if (pin->enable_irq_failed) {
cec_pin_to_idle(pin);
hrtimer_start(&pin->timer, ns_to_ktime(0),
HRTIMER_MODE_REL);
} else {
irq_enabled = true;
}
break;
default:
break;
}
if (kthread_should_stop())
break;
}
if (pin->ops->disable_irq && irq_enabled)
pin->ops->disable_irq(adap);
hrtimer_cancel(&pin->timer);
cec_pin_read(pin);
cec_pin_to_idle(pin);
pin->state = CEC_ST_OFF;
return 0;
}
@ -1129,13 +1143,7 @@ static int cec_pin_adap_enable(struct cec_adapter *adap, bool enable)
hrtimer_start(&pin->timer, ns_to_ktime(0),
HRTIMER_MODE_REL);
} else {
if (pin->ops->disable_irq)
pin->ops->disable_irq(adap);
hrtimer_cancel(&pin->timer);
kthread_stop(pin->kthread);
cec_pin_read(pin);
cec_pin_to_idle(pin);
pin->state = CEC_ST_OFF;
}
return 0;
}
@ -1156,11 +1164,8 @@ void cec_pin_start_timer(struct cec_pin *pin)
if (pin->state != CEC_ST_RX_IRQ)
return;
atomic_set(&pin->work_irq_change, CEC_PIN_IRQ_UNCHANGED);
pin->ops->disable_irq(pin->adap);
cec_pin_high(pin);
cec_pin_to_idle(pin);
hrtimer_start(&pin->timer, ns_to_ktime(0), HRTIMER_MODE_REL);
atomic_set(&pin->work_irq_change, CEC_PIN_IRQ_DISABLE);
wake_up_interruptible(&pin->kthread_waitq);
}
static int cec_pin_adap_transmit(struct cec_adapter *adap, u8 attempts,