From 3589972e51fac1e02d0aaa576fa47f568cb94d40 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Fri, 4 Dec 2009 11:06:57 -0500 Subject: [PATCH] Driver core: fix race in dev_driver_string This patch (as1310) works around a race in dev_driver_string(). If the device is unbound while the function is running, dev->driver might become NULL after we test it and before we dereference it. Signed-off-by: Alan Stern Cc: stable Cc: Oliver Neukum Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 353b13782165..f1290cbd1350 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -56,7 +56,14 @@ static inline int device_is_not_partition(struct device *dev) */ const char *dev_driver_string(const struct device *dev) { - return dev->driver ? dev->driver->name : + struct device_driver *drv; + + /* dev->driver can change to NULL underneath us because of unbinding, + * so be careful about accessing it. dev->bus and dev->class should + * never change once they are set, so they don't need special care. + */ + drv = ACCESS_ONCE(dev->driver); + return drv ? drv->name : (dev->bus ? dev->bus->name : (dev->class ? dev->class->name : "")); } -- 2.20.1