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-rw-r--r--Documentation/kobject.txt10
-rw-r--r--drivers/base/core.c3
-rw-r--r--include/linux/kref.h5
-rw-r--r--lib/kobject.c2
4 files changed, 10 insertions, 10 deletions
diff --git a/Documentation/kobject.txt b/Documentation/kobject.txt
index fc9485d79061..ff4c25098119 100644
--- a/Documentation/kobject.txt
+++ b/Documentation/kobject.txt
@@ -279,10 +279,14 @@ such a method has a form like::
One important point cannot be overstated: every kobject must have a
release() method, and the kobject must persist (in a consistent state)
until that method is called. If these constraints are not met, the code is
-flawed. Note that the kernel will warn you if you forget to provide a
+flawed. Note that the kernel will warn you if you forget to provide a
release() method. Do not try to get rid of this warning by providing an
-"empty" release function; you will be mocked mercilessly by the kobject
-maintainer if you attempt this.
+"empty" release function.
+
+If all your cleanup function needs to do is call kfree(), then you must
+create a wrapper function which uses container_of() to upcast to the correct
+type (as shown in the example above) and then calls kfree() on the overall
+structure.
Note, the name of the kobject is available in the release function, but it
must NOT be changed within this callback. Otherwise there will be a memory
diff --git a/drivers/base/core.c b/drivers/base/core.c
index ed145fbfeddf..e2285059161d 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -897,8 +897,7 @@ static void device_release(struct kobject *kobj)
else if (dev->class && dev->class->dev_release)
dev->class->dev_release(dev);
else
- WARN(1, KERN_ERR "Device '%s' does not have a release() "
- "function, it is broken and must be fixed.\n",
+ WARN(1, KERN_ERR "Device '%s' does not have a release() function, it is broken and must be fixed. See Documentation/kobject.txt.\n",
dev_name(dev));
kfree(p);
}
diff --git a/include/linux/kref.h b/include/linux/kref.h
index 29220724bf1c..cb00a0268061 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -53,10 +53,7 @@ static inline void kref_get(struct kref *kref)
* @release: pointer to the function that will clean up the object when the
* last reference to the object is released.
* This pointer is required, and it is not acceptable to pass kfree
- * in as this function. If the caller does pass kfree to this
- * function, you will be publicly mocked mercilessly by the kref
- * maintainer, and anyone else who happens to notice it. You have
- * been warned.
+ * in as this function.
*
* Decrement the refcount, and if 0, call release().
* Return 1 if the object was removed, otherwise return 0. Beware, if this
diff --git a/lib/kobject.c b/lib/kobject.c
index 97d86dc17c42..b72e00fd7d09 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -639,7 +639,7 @@ static void kobject_cleanup(struct kobject *kobj)
kobject_name(kobj), kobj, __func__, kobj->parent);
if (t && !t->release)
- pr_debug("kobject: '%s' (%p): does not have a release() function, it is broken and must be fixed.\n",
+ pr_debug("kobject: '%s' (%p): does not have a release() function, it is broken and must be fixed. See Documentation/kobject.txt.\n",
kobject_name(kobj), kobj);
/* send "remove" if the caller did not do it but sent "add" */