From: Ming Lei Date: Fri, 22 Jun 2012 10:01:40 +0000 (+0800) Subject: driver core: fix shutdown races with probe/remove(v3) X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d1c6c030fcec6f860d9bb6c632a3ebe62e28440b;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git driver core: fix shutdown races with probe/remove(v3) Firstly, .shutdown callback may touch a uninitialized hardware if dev->driver is set and .probe is not completed. Secondly, device_shutdown() may dereference a null pointer to cause oops when dev->driver is cleared after it has been checked in device_shutdown(). So just hold device lock and its parent lock(if it has) to fix the races. Cc: Alan Stern Signed-off-by: Ming Lei Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/base/core.c b/drivers/base/core.c index 846d12b5d579..65849a9aeece 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1812,6 +1812,13 @@ void device_shutdown(void) while (!list_empty(&devices_kset->list)) { dev = list_entry(devices_kset->list.prev, struct device, kobj.entry); + + /* + * hold reference count of device's parent to + * prevent it from being freed because parent's + * lock is to be held + */ + get_device(dev->parent); get_device(dev); /* * Make sure the device is off the kset list, in the @@ -1820,6 +1827,11 @@ void device_shutdown(void) list_del_init(&dev->kobj.entry); spin_unlock(&devices_kset->list_lock); + /* hold lock to avoid race with probe/release */ + if (dev->parent) + device_lock(dev->parent); + device_lock(dev); + /* Don't allow any more runtime suspends */ pm_runtime_get_noresume(dev); pm_runtime_barrier(dev); @@ -1831,7 +1843,13 @@ void device_shutdown(void) dev_dbg(dev, "shutdown\n"); dev->driver->shutdown(dev); } + + device_unlock(dev); + if (dev->parent) + device_unlock(dev->parent); + put_device(dev); + put_device(dev->parent); spin_lock(&devices_kset->list_lock); }