[patch -mm] notifier chain initialization

[patch -mm] notifier chain initialization

[Jes Sorensen]

Hi,

This one is against the -mm tree, description below.

Cheers,
Jes

This patch goes on top of Alan Stern's
notifier-chain-update-api-changes.patch

It restructures the notifier chain initialization macros by
introducing FOO_NOTIFIER_INIT() macros which are used by the
FOO_NOTIFIER_HEAD() macros.

The benefit is that one can use the FOO_NOTIFIER_INIT() macro for
static initialization of a notifier chain.

Signed-off-by: Jes Sorensen <jes@sgi.com>

---
 include/linux/notifier.h |   19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

Index: linux-2.6/include/linux/notifier.h
===================================================================
--- linux-2.6.orig/include/linux/notifier.h
+++ linux-2.6/include/linux/notifier.h
@@ -64,17 +64,24 @@
 		(name)->head = NULL;		\
 	} while (0)
 
-#define ATOMIC_NOTIFIER_HEAD(name)				\
-	struct atomic_notifier_head name = {			\
+#define ATOMIC_NOTIFIER_INIT(name) {				\
 		.mutex = __MUTEX_INITIALIZER((name).mutex),	\
 		.head = NULL }
-#define BLOCKING_NOTIFIER_HEAD(name)				\
-	struct blocking_notifier_head name = {			\
+#define BLOCKING_NOTIFIER_INIT(name) {				\
 		.rwsem = __RWSEM_INITIALIZER((name).rwsem),	\
 		.head = NULL }
+#define RAW_NOTIFIER_INIT(name) {				\
+		.head = NULL }
+
+#define ATOMIC_NOTIFIER_HEAD(name)				\
+	struct atomic_notifier_head name =			\
+		ATOMIC_NOTIFIER_INIT(name)
+#define BLOCKING_NOTIFIER_HEAD(name)				\
+	struct blocking_notifier_head name =			\
+		BLOCKING_NOTIFIER_INIT(name)
 #define RAW_NOTIFIER_HEAD(name)					\
-	struct raw_notifier_head name = {			\
-	.head = NULL }
+	struct raw_notifier_head name =				\
+		RAW_NOTIFIER_INIT(name)
 
 #ifdef __KERNEL__
 

Re: [patch -mm] notifier chain initialization

[Alan Stern]

On 22 Mar 2006, Jes Sorensen wrote:

> Hi,
> 
> This one is against the -mm tree, description below.
> 
> Cheers,
> Jes
> 
> This patch goes on top of Alan Stern's
> notifier-chain-update-api-changes.patch
> 
> It restructures the notifier chain initialization macros by
> introducing FOO_NOTIFIER_INIT() macros which are used by the
> FOO_NOTIFIER_HEAD() macros.
> 
> The benefit is that one can use the FOO_NOTIFIER_INIT() macro for
> static initialization of a notifier chain.

You probably mean _dynamic_ initialization of a notifier head.  The 
current code handles static initialization just fine.

There's nothing wrong with doing things like this.  I didn't include 
initialization macros originally simply because there aren't any 
dynamically-initialized notifier heads in the kernel.

Alan Stern

Re: [patch -mm] notifier chain initialization

[Jes Sorensen]

Alan Stern wrote:
>> The benefit is that one can use the FOO_NOTIFIER_INIT() macro for
>> static initialization of a notifier chain.
> 
> You probably mean _dynamic_ initialization of a notifier head.  The 
> current code handles static initialization just fine.

Actually I meant static, I have a notifier declared within a struct and
a macro that initializes it at compile time - didn't work with the old
code.

But I also use it dynamically where this also benefits it.

> There's nothing wrong with doing things like this.  I didn't include 
> initialization macros originally simply because there aren't any 
> dynamically-initialized notifier heads in the kernel.

There probably will be :)

Cheers,
Jes