On 2024/07/13 4:42, Dan Williams wrote:
@@ -2668,8 +2670,12 @@ static int dev_uevent(const struct kobject *kobj, struct kobj_uevent_env *env) if (dev->type && dev->type->name) add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
- if (dev->driver)
add_uevent_var(env, "DRIVER=%s", dev->driver->name);
- /* Synchronize with module_remove_driver() */
- rcu_read_lock();
- driver = READ_ONCE(dev->driver);
- if (driver)
add_uevent_var(env, "DRIVER=%s", driver->name);
- rcu_read_unlock();
Given that read of dev->driver is protected using RCU,
@@ -97,6 +98,9 @@ void module_remove_driver(struct device_driver *drv) if (!drv) return;
where is
dev->driver = NULL;
performed prior to
- /* Synchronize with dev_uevent() */
- synchronize_rcu();
this synchronize_rcu(), in order to make sure that READ_ONCE(dev->driver) in dev_uevent() observes NULL?
sysfs_remove_link(&drv->p->kobj, "module"); if (drv->owner)