diff mbox series

[v2,01/10] usb: typec: Take care of driver module reference counting

Message ID 20180903133616.71051-2-heikki.krogerus@linux.intel.com (mailing list archive)
State Deferred, archived
Delegated to: Andy Shevchenko
Headers show
Series usb: typec: A few more improvements for Intel CHT | expand

Commit Message

Heikki Krogerus Sept. 3, 2018, 1:36 p.m. UTC
Functions typec_mux_get() and typec_switch_get() already
make sure that the mux device reference count is
incremented, but the same must be done to the driver module
as well to prevent the drivers from being unloaded in the
middle of operation.

This fixes a potential "BUG: unable to handle kernel paging
request at ..." from happening.

Fixes: 93dd2112c7b2 ("usb: typec: mux: Get the mux identifier from function parameter")
Cc: <stable@vger.kernel.org>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
 drivers/usb/typec/mux.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/usb/typec/mux.c b/drivers/usb/typec/mux.c
index ddaac63ecf12..d990aa510fab 100644
--- a/drivers/usb/typec/mux.c
+++ b/drivers/usb/typec/mux.c
@@ -9,6 +9,7 @@ 
 
 #include <linux/device.h>
 #include <linux/list.h>
+#include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/usb/typec_mux.h>
 
@@ -49,8 +50,10 @@  struct typec_switch *typec_switch_get(struct device *dev)
 	mutex_lock(&switch_lock);
 	sw = device_connection_find_match(dev, "typec-switch", NULL,
 					  typec_switch_match);
-	if (!IS_ERR_OR_NULL(sw))
+	if (!IS_ERR_OR_NULL(sw)) {
+		WARN_ON(!try_module_get(sw->dev->driver->owner));
 		get_device(sw->dev);
+	}
 	mutex_unlock(&switch_lock);
 
 	return sw;
@@ -65,8 +68,10 @@  EXPORT_SYMBOL_GPL(typec_switch_get);
  */
 void typec_switch_put(struct typec_switch *sw)
 {
-	if (!IS_ERR_OR_NULL(sw))
+	if (!IS_ERR_OR_NULL(sw)) {
+		module_put(sw->dev->driver->owner);
 		put_device(sw->dev);
+	}
 }
 EXPORT_SYMBOL_GPL(typec_switch_put);
 
@@ -136,8 +141,10 @@  struct typec_mux *typec_mux_get(struct device *dev, const char *name)
 
 	mutex_lock(&mux_lock);
 	mux = device_connection_find_match(dev, name, NULL, typec_mux_match);
-	if (!IS_ERR_OR_NULL(mux))
+	if (!IS_ERR_OR_NULL(mux)) {
+		WARN_ON(!try_module_get(mux->dev->driver->owner));
 		get_device(mux->dev);
+	}
 	mutex_unlock(&mux_lock);
 
 	return mux;
@@ -152,8 +159,10 @@  EXPORT_SYMBOL_GPL(typec_mux_get);
  */
 void typec_mux_put(struct typec_mux *mux)
 {
-	if (!IS_ERR_OR_NULL(mux))
+	if (!IS_ERR_OR_NULL(mux)) {
+		module_put(mux->dev->driver->owner);
 		put_device(mux->dev);
+	}
 }
 EXPORT_SYMBOL_GPL(typec_mux_put);