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Subject: media: cec-pin: fix interrupt en/disable handling Author: Hans Verkuil hverkuil-cisco@xs4all.nl Date: Wed Dec 1 13:41:25 2021 +0100
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: 865463fc03ed (media: cec-pin: add error injection support) Cc: stable@vger.kernel.org Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org
drivers/media/cec/core/cec-pin.c | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-)
---
diff --git a/drivers/media/cec/core/cec-pin.c b/drivers/media/cec/core/cec-pin.c index 2b6459df1e94..21f0f749713e 100644 --- a/drivers/media/cec/core/cec-pin.c +++ b/drivers/media/cec/core/cec-pin.c @@ -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,