[PATCH v3 11/11] hwmon: chipcap2: synchronize ready IRQ state

[Javier Carrasco <javier.carrasco.cruz@gmail.com>]

The ready IRQ handler can race with reinit_completion() in the enable
path. In particular, a handler from an earlier operation can complete
the completion after it is reset for a new operation.

Use irq_lock to serialize access to the completion and process_irqs.
Disable IRQ processing and synchronize any running handler before resetting
the completion for a new operation.

Fixes: 3af350929e75 ("hwmon: Add support for Amphenol ChipCap 2")
Cc: stable@vger.kernel.org
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Assisted-by: opencode:claude-opus-5
---
 drivers/hwmon/chipcap2.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/hwmon/chipcap2.c b/drivers/hwmon/chipcap2.c
index b3b725cc7224..00f62a33d463 100644
--- a/drivers/hwmon/chipcap2.c
+++ b/drivers/hwmon/chipcap2.c
@@ -123,6 +123,16 @@ static int cc2_enable(struct cc2_data *data)
 {
 	int ret;
 
+	if (data->irq_ready > 0) {
+		scoped_guard(mutex, &data->irq_lock)
+			data->process_irqs = false;
+
+		synchronize_irq(data->irq_ready);
+
+		scoped_guard(mutex, &data->irq_lock)
+			reinit_completion(&data->complete);
+	}
+
 	/* exclusive regulator, check in case a disable failed */
 	if (data->regulator_enabled) {
 		scoped_guard(mutex, &data->irq_lock)
@@ -130,9 +140,6 @@ static int cc2_enable(struct cc2_data *data)
 		return 0;
 	}
 
-	/* clear any pending completion */
-	try_wait_for_completion(&data->complete);
-
 	ret = regulator_enable(data->regulator);
 	if (ret < 0)
 		return ret;
@@ -162,6 +169,9 @@ static void cc2_disable(struct cc2_data *data)
 	scoped_guard(mutex, &data->irq_lock)
 		data->process_irqs = false;
 
+	if (data->irq_ready > 0)
+		synchronize_irq(data->irq_ready);
+
 	/* exclusive regulator, check in case an enable failed */
 	if (!data->regulator_enabled)
 		return;
@@ -510,8 +520,10 @@ static irqreturn_t cc2_ready_interrupt(int irq, void *data)
 {
 	struct cc2_data *cc2 = data;
 
-	if (cc2->process_irqs)
-		complete(&cc2->complete);
+	scoped_guard(mutex, &cc2->irq_lock) {
+		if (cc2->process_irqs)
+			complete(&cc2->complete);
+	}
 
 	return IRQ_HANDLED;
 }

-- 
2.43.0