From 094e47e9fa79e28f0e51e37400ea6eea35a4ee1f Mon Sep 17 00:00:00 2001 From: Hiroshi DOYU Date: Fri, 11 May 2012 11:03:09 +0300 Subject: [PATCH] Driver Core: don't oops with unregistered driver in driver_find_device() driver_find_device() can be called with an unregistered driver. Need to check driver_private to see if it's populated or not, especially under deferrable probe. In the case that there are 2 drivers, one depends on the other. With -EPROBE_DEFER, two drivers can use deferred probe to ensure that their relative probe order doesn't matter. If dependee driver is probed first, then the dependant's driver_find_device('dependee') succeeds. If the dependant is probed first, then the dependant's driver_find_device('dependee') should return NULL, and the dependant should get -EPROBE_DEFER. driver_find_device() needs to return NULL if it's not populated. In [PATCHv5 2/3] ARM: tegra: Add SMMU enabler in AHB: http://article.gmane.org/gmane.linux.ports.tegra/4658 "tegra_ahb_driver" may not be populated when it's called. For more SMMU/AHB specific discussion, refer to the following thread: https://lkml.org/lkml/2012/5/10/21 Signed-off-by: Hiroshi DOYU Cc: Stephen Warren Signed-off-by: Greg Kroah-Hartman --- drivers/base/driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/base/driver.c b/drivers/base/driver.c index 3ec3896c83a..207c27ddf82 100644 --- a/drivers/base/driver.c +++ b/drivers/base/driver.c @@ -80,7 +80,7 @@ struct device *driver_find_device(struct device_driver *drv, struct klist_iter i; struct device *dev; - if (!drv) + if (!drv || !drv->p) return NULL; klist_iter_init_node(&drv->p->klist_devices, &i,