usb: roles: fix NULL pointer issue when put module's reference
In current design, usb role class driver will get usb_role_switch parent's module reference after the user get usb_role_switch device and put the reference after the user put the usb_role_switch device. However, the parent device of usb_role_switch may be removed before the user put the usb_role_switch. If so, then, NULL pointer issue will be met when the user put the parent module's reference. This will save the module pointer in structure of usb_role_switch. Then, we don't need to find module by iterating long relations. Fixes: 5c54fcac9a9d ("usb: roles: Take care of driver module reference counting") cc: stable@vger.kernel.org Signed-off-by: Xu Yang <xu.yang_2@nxp.com> Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Link: https://lore.kernel.org/r/20240129093739.2371530-1-xu.yang_2@nxp.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -21,6 +21,7 @@ static const struct class role_class = {
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struct usb_role_switch {
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struct device dev;
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struct mutex lock; /* device lock*/
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struct module *module; /* the module this device depends on */
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enum usb_role role;
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/* From descriptor */
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@ -135,7 +136,7 @@ struct usb_role_switch *usb_role_switch_get(struct device *dev)
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usb_role_switch_match);
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if (!IS_ERR_OR_NULL(sw))
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WARN_ON(!try_module_get(sw->dev.parent->driver->owner));
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WARN_ON(!try_module_get(sw->module));
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return sw;
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}
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@ -157,7 +158,7 @@ struct usb_role_switch *fwnode_usb_role_switch_get(struct fwnode_handle *fwnode)
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sw = fwnode_connection_find_match(fwnode, "usb-role-switch",
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NULL, usb_role_switch_match);
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if (!IS_ERR_OR_NULL(sw))
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WARN_ON(!try_module_get(sw->dev.parent->driver->owner));
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WARN_ON(!try_module_get(sw->module));
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return sw;
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}
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@ -172,7 +173,7 @@ EXPORT_SYMBOL_GPL(fwnode_usb_role_switch_get);
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void usb_role_switch_put(struct usb_role_switch *sw)
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{
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if (!IS_ERR_OR_NULL(sw)) {
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module_put(sw->dev.parent->driver->owner);
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module_put(sw->module);
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put_device(&sw->dev);
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}
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}
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@ -189,15 +190,18 @@ struct usb_role_switch *
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usb_role_switch_find_by_fwnode(const struct fwnode_handle *fwnode)
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{
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struct device *dev;
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struct usb_role_switch *sw = NULL;
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if (!fwnode)
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return NULL;
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dev = class_find_device_by_fwnode(&role_class, fwnode);
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if (dev)
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WARN_ON(!try_module_get(dev->parent->driver->owner));
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if (dev) {
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sw = to_role_switch(dev);
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WARN_ON(!try_module_get(sw->module));
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}
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return dev ? to_role_switch(dev) : NULL;
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return sw;
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}
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EXPORT_SYMBOL_GPL(usb_role_switch_find_by_fwnode);
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@ -338,6 +342,7 @@ usb_role_switch_register(struct device *parent,
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sw->set = desc->set;
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sw->get = desc->get;
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sw->module = parent->driver->owner;
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sw->dev.parent = parent;
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sw->dev.fwnode = desc->fwnode;
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sw->dev.class = &role_class;
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