linux-kernel - [PATCH 5.10 006/530] usb: roles: Call try_module_get() from usb_role_switch_find_by

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Date:   Wed, 12 May 2021 16:41:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>
Subject: [PATCH 5.10 006/530] usb: roles: Call try_module_get() from usb_role_switch_find_by_fwnode()

From: Hans de Goede <hdegoede@...hat.com>

commit 3a2a91a2d51761557843996a66098eb7182b48b4 upstream.

usb_role_switch_find_by_fwnode() returns a reference to the role-switch
which must be put by calling usb_role_switch_put().

usb_role_switch_put() calls module_put(sw->dev.parent->driver->owner),
add a matching try_module_get() to usb_role_switch_find_by_fwnode(),
making it behave the same as the other usb_role_switch functions
which return a reference.

This avoids a WARN_ON being hit at kernel/module.c:1158 due to the
module-refcount going below 0.

Fixes: c6919d5e0cd1 ("usb: roles: Add usb_role_switch_find_by_fwnode()")
Cc: stable <stable@...r.kernel.org>
Reviewed-by: Guenter Roeck <linux@...ck-us.net>
Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@...hat.com>
Link: https://lore.kernel.org/r/20210409124136.65591-1-hdegoede@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/usb/roles/class.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/usb/roles/class.c
+++ b/drivers/usb/roles/class.c
@@ -189,6 +189,8 @@ usb_role_switch_find_by_fwnode(const str
 		return NULL;
 
 	dev = class_find_device_by_fwnode(role_class, fwnode);
+	if (dev)
+		WARN_ON(!try_module_get(dev->parent->driver->owner));
 
 	return dev ? to_role_switch(dev) : NULL;
 }