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>

diff --git a/drivers/base/class.c b/drivers/base/class.c
index 5667c2f02c51b2249fdac0d69fc7fd0a8fe4dfd0..cc5e28c8885ce1b78d2b0453e9068c8abf0dde64 100644 (file)
--- 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) {