media: cec-pin: fix irq handling

The free_irq() function could be called from interrupt context,
which is invalid. Move this to the thread.

In the interrupt handler we just request that the thread disables
the irq. This is done through an atomic so we don't need to add
any spinlocks.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 21 insertions, 13 deletions

diff --git a/drivers/media/cec/cec-pin.c b/drivers/media/cec/cec-pin.c
index 31a26d3b8bd8..970774de3dcd 100644
--- a/drivers/media/cec/cec-pin.c
+++ b/drivers/media/cec/cec-pin.c
@@ -557,7 +557,7 @@ static enum hrtimer_restart cec_pin_timer(struct hrtimer *timer)
 		    adap->is_configured || adap->monitor_all_cnt)
 			break;
 		/* Switch to interrupt mode */
-		pin->work_enable_irq = true;
+		atomic_set(&pin->work_irq_change, CEC_PIN_IRQ_ENABLE);
 		pin->state = CEC_ST_RX_IRQ;
 		wake_up_interruptible(&pin->kthread_waitq);
 		return HRTIMER_NORESTART;
@@ -591,7 +591,7 @@ static int cec_pin_thread_func(void *_adap)
 			kthread_should_stop() ||
 			pin->work_rx_msg.len ||
 			pin->work_tx_status ||
-			pin->work_enable_irq ||
+			atomic_read(&pin->work_irq_change) ||
 			atomic_read(&pin->work_pin_events));
 
 		if (pin->work_rx_msg.len) {
@@ -606,6 +606,7 @@ static int cec_pin_thread_func(void *_adap)
 			cec_transmit_attempt_done_ts(adap, tx_status,
 						     pin->work_tx_ts);
 		}
+
 		while (atomic_read(&pin->work_pin_events)) {
 			unsigned int idx = pin->work_pin_events_rd;
 
@@ -615,14 +616,26 @@ static int cec_pin_thread_func(void *_adap)
 			pin->work_pin_events_rd = (idx + 1) % CEC_NUM_PIN_EVENTS;
 			atomic_dec(&pin->work_pin_events);
 		}
-		if (pin->work_enable_irq) {
-			pin->work_enable_irq = false;
+
+		switch (atomic_xchg(&pin->work_irq_change,
+				    CEC_PIN_IRQ_UNCHANGED)) {
+		case CEC_PIN_IRQ_DISABLE:
+			pin->ops->disable_irq(adap);
+			cec_pin_high(pin);
+			cec_pin_to_idle(pin);
+			hrtimer_start(&pin->timer, 0, HRTIMER_MODE_REL);
+			break;
+		case CEC_PIN_IRQ_ENABLE:
 			pin->enable_irq_failed = !pin->ops->enable_irq(adap);
 			if (pin->enable_irq_failed) {
 				cec_pin_to_idle(pin);
 				hrtimer_start(&pin->timer, 0, HRTIMER_MODE_REL);
 			}
+			break;
+		default:
+			break;
 		}
+
 		if (kthread_should_stop())
 			break;
 	}
@@ -641,7 +654,7 @@ static int cec_pin_adap_enable(struct cec_adapter *adap, bool enable)
 		cec_pin_to_idle(pin);
 		pin->tx_msg.len = 0;
 		pin->timer_ts = 0;
-		pin->work_enable_irq = false;
+		atomic_set(&pin->work_irq_change, CEC_PIN_IRQ_UNCHANGED);
 		pin->kthread = kthread_run(cec_pin_thread_func, adap,
 					   "cec-pin");
 		if (IS_ERR(pin->kthread)) {
@@ -682,7 +695,7 @@ static int cec_pin_adap_transmit(struct cec_adapter *adap, u8 attempts,
 	pin->work_tx_status = 0;
 	pin->tx_bit = 0;
 	if (pin->state == CEC_ST_RX_IRQ) {
-		pin->work_enable_irq = false;
+		atomic_set(&pin->work_irq_change, CEC_PIN_IRQ_UNCHANGED);
 		pin->ops->disable_irq(adap);
 		cec_pin_high(pin);
 		cec_pin_to_idle(pin);
@@ -745,13 +758,8 @@ void cec_pin_changed(struct cec_adapter *adap, bool value)
 
 	cec_pin_update(pin, value, false);
 	if (!value && (adap->is_configuring || adap->is_configured ||
-		       adap->monitor_all_cnt)) {
-		pin->work_enable_irq = false;
-		pin->ops->disable_irq(adap);
-		cec_pin_high(pin);
-		cec_pin_to_idle(pin);
-		hrtimer_start(&pin->timer, 0, HRTIMER_MODE_REL);
-	}
+		       adap->monitor_all_cnt))
+		atomic_set(&pin->work_irq_change, CEC_PIN_IRQ_DISABLE);
 }
 EXPORT_SYMBOL_GPL(cec_pin_changed);