Input: rotary_encoder - use guard notation when acquiring mutex

Using guard notation makes the code more compact and error handling
more robust by ensuring that mutexes are released in all code paths
when control leaves critical section.

Reviewed-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240904044929.1049700-1-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/rotary_encoder.c

@@ -106,7 +106,7 @@ static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
 	struct rotary_encoder *encoder = dev_id;
 	unsigned int state;
 
-	mutex_lock(&encoder->access_mutex);
+	guard(mutex)(&encoder->access_mutex);
 
 	state = rotary_encoder_get_state(encoder);
 
@@ -129,8 +129,6 @@ static irqreturn_t rotary_encoder_irq(int irq, void *dev_id)
 		break;
 	}
 
-	mutex_unlock(&encoder->access_mutex);
-
 	return IRQ_HANDLED;
 }
 
@@ -139,7 +137,7 @@ static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
 	struct rotary_encoder *encoder = dev_id;
 	unsigned int state;
 
-	mutex_lock(&encoder->access_mutex);
+	guard(mutex)(&encoder->access_mutex);
 
 	state = rotary_encoder_get_state(encoder);
 
@@ -152,8 +150,6 @@ static irqreturn_t rotary_encoder_half_period_irq(int irq, void *dev_id)
 		}
 	}
 
-	mutex_unlock(&encoder->access_mutex);
-
 	return IRQ_HANDLED;
 }
 
@@ -162,22 +158,19 @@ static irqreturn_t rotary_encoder_quarter_period_irq(int irq, void *dev_id)
 	struct rotary_encoder *encoder = dev_id;
 	unsigned int state;
 
-	mutex_lock(&encoder->access_mutex);
+	guard(mutex)(&encoder->access_mutex);
 
 	state = rotary_encoder_get_state(encoder);
 
-	if ((encoder->last_stable + 1) % 4 == state)
+	if ((encoder->last_stable + 1) % 4 == state) {
 		encoder->dir = 1;
-	else if (encoder->last_stable == (state + 1) % 4)
+		rotary_encoder_report_event(encoder);
+	} else if (encoder->last_stable == (state + 1) % 4) {
 		encoder->dir = -1;
-	else
-		goto out;
-
-	rotary_encoder_report_event(encoder);
+		rotary_encoder_report_event(encoder);
+	}
 
-out:
 	encoder->last_stable = state;
-	mutex_unlock(&encoder->access_mutex);
 
 	return IRQ_HANDLED;
 }