[PATCH 06/10] mei: vsc: Event notifier fixes

[Hans de Goede <hansg@kernel.org>]

vsc_tp_register_event_cb() can race with vsc_tp_thread_isr(), add a mutex
to protect against this.

Fixes: 566f5ca97680 ("mei: Add transport driver for IVSC device")
Signed-off-by: Hans de Goede <hansg@kernel.org>
---
 drivers/misc/mei/vsc-tp.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/mei/vsc-tp.c b/drivers/misc/mei/vsc-tp.c
index 0feebffabdb3..76a6aa606a26 100644
--- a/drivers/misc/mei/vsc-tp.c
+++ b/drivers/misc/mei/vsc-tp.c
@@ -79,9 +79,8 @@ struct vsc_tp {
 
 	vsc_tp_event_cb_t event_notify;
 	void *event_notify_context;
-
-	/* used to protect command download */
-	struct mutex mutex;
+	struct mutex event_notify_mutex;	/* protects event_notify + context */
+	struct mutex mutex;			/* protects command download */
 };
 
 /* GPIO resources */
@@ -113,6 +112,8 @@ static irqreturn_t vsc_tp_thread_isr(int irq, void *data)
 {
 	struct vsc_tp *tp = data;
 
+	guard(mutex)(&tp->event_notify_mutex);
+
 	if (tp->event_notify)
 		tp->event_notify(tp->event_notify_context);
 
@@ -399,6 +400,8 @@ EXPORT_SYMBOL_NS_GPL(vsc_tp_need_read, "VSC_TP");
 int vsc_tp_register_event_cb(struct vsc_tp *tp, vsc_tp_event_cb_t event_cb,
 			    void *context)
 {
+	guard(mutex)(&tp->event_notify_mutex);
+
 	tp->event_notify = event_cb;
 	tp->event_notify_context = context;
 
@@ -499,6 +502,7 @@ static int vsc_tp_probe(struct spi_device *spi)
 		return ret;
 
 	mutex_init(&tp->mutex);
+	mutex_init(&tp->event_notify_mutex);
 
 	/* only one child acpi device */
 	ret = acpi_dev_for_each_child(ACPI_COMPANION(dev),
@@ -523,6 +527,7 @@ static int vsc_tp_probe(struct spi_device *spi)
 err_destroy_lock:
 	free_irq(spi->irq, tp);
 
+	mutex_destroy(&tp->event_notify_mutex);
 	mutex_destroy(&tp->mutex);
 
 	return ret;
@@ -537,6 +542,7 @@ static void vsc_tp_remove(struct spi_device *spi)
 
 	free_irq(spi->irq, tp);
 
+	mutex_destroy(&tp->event_notify_mutex);
 	mutex_destroy(&tp->mutex);
 }
 
-- 
2.49.0