Subject: Re: A better way to sequence driver initialization?

From: Bill Gatliff <[email-masked]>
Date: Fri, 09 Apr 2010 23:19:52 -0500

Bill Gatliff wrote:
>
> ... and kset_register() might be the only place that calls
> wake_up_interruptible().  Wow.
>   

Wow, indeed.  With just the attached patch, I get exactly one OOPS
now--- in ssc_free(), which I think is getting called because
atmel_ssc_modinit() is racing with something.

I wasn't able to get all the way to mounting my NFS rootfs, I think
because I'm getting to ip_auto_config() before my ethernet controller
has registered!  :)

$ git diff lib/kobject.c
diff --git a/lib/kobject.c b/lib/kobject.c
index b512b74..e75556c 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -18,6 +18,10 @@
 #include <linux/stat.h>
 #include <linux/slab.h>

+#include <linux/sched.h>
+#include <linux/wait.h>
+DECLARE_WAIT_QUEUE_HEAD(kset_wait);
+
 /*
  * populate_dir - populate directory with attributes.
  * @kobj: object we're working on.
@@ -721,6 +725,7 @@ int kset_register(struct kset *k)
        if (err)
                return err;
        kobject_uevent(&k->kobj, KOBJ_ADD);
+       wake_up_interruptible(&kset_wait);
        return 0;
 }

@@ -744,7 +749,7 @@ void kset_unregister(struct kset *k)
  * looking for a matching kobject. If matching object is found
  * take a reference and return the object.
  */
-struct kobject *kset_find_obj(struct kset *kset, const char *name)
+struct kobject *__kset_find_obj(struct kset *kset, const char *name)
 {
        struct kobject *k;
        struct kobject *ret = NULL;
@@ -760,6 +765,14 @@ struct kobject *kset_find_obj(struct kset *kset,
const char *name)
        return ret;
 }

+struct kobject *kset_find_obj(struct kset *kset, const char *name)
+{
+       struct kobject *ret = NULL;
+       wait_event_interruptible(kset_wait, (ret = __kset_find_obj(kset,
name)));
+       return ret;
+}
+
 static void kset_release(struct kobject *kobj)
 {
        struct kset *kset = container_of(kobj, struct kset, kobj);

b.g.

-- 
Bill Gatliff
[email-masked]