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authorAlan Stern <stern@rowland.harvard.edu>2009-12-04 11:06:57 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2009-12-11 11:24:55 -0800
commit3589972e51fac1e02d0aaa576fa47f568cb94d40 (patch)
tree05e89c751f410a3b54583f948ff9ffc841c333ea
parentc60e0504c8e4fa14179d0687d80ef25148dd6dd4 (diff)
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 <stern@rowland.harvard.edu> Cc: stable <stable@kernel.org> Cc: Oliver Neukum <oliver@neukum.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/base/core.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 353b1378216..f1290cbd135 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 : ""));
}