driver model: anti-oopsing medicine

Anti-oops medicine for the class iterators ... the oops was
observed when a class was implicitly referenced before it
was initialized.

[Modified by Greg to spit a warning back so someone knows to fix their code]

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/base/class.c b/drivers/base/class.c
index 5667c2f02c51..cc5e28c8885c 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -295,6 +295,12 @@ int class_for_each_device(struct class *class, struct device *start,
 
         if (!class)
                 return -EINVAL;
+        if (!class->p) {
+                WARN(1, "%s called for class '%s' before it was initialized",
+                     __func__, class->name);
+                return -EINVAL;
+        }
+
         mutex_lock(&class->p->class_mutex);
         list_for_each_entry(dev, &class->p->class_devices, node) {
                 if (start) {
@@ -344,6 +350,11 @@ struct device *class_find_device(struct class *class, struct device *start,
 
         if (!class)
                 return NULL;
+        if (!class->p) {
+                WARN(1, "%s called for class '%s' before it was initialized",
+                     __func__, class->name);
+                return NULL;
+        }
 
         mutex_lock(&class->p->class_mutex);
         list_for_each_entry(dev, &class->p->class_devices, node) {