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usb: typec: mux: Take care of driver module reference counting 

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: 93dd2112c7 ("usb: typec: mux: Get the mux identifier from function parameter")
Acked-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Heikki Krogerus 2018-09-19 10:58:04 +03:00 committed by Greg Kroah-Hartman
parent 16c4cb19fa
commit 3e3b81965c
1 changed files with 13 additions and 4 deletions
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17
drivers/usb/typec/mux.c
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@ -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);