[PATCH] RCU in kernel/intermodule.c

[PATCH] RCU in kernel/intermodule.c

[Luca Falavigna]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

This patch, compiled against version 2.6.12-rc1, implements RCU mechanism in
intermodule functions.



Signed-off-by: Luca Falavigna <dktrkranz@gmail.com>

- --- ./kernel/intermodule.c.orig	2005-04-01 19:25:26.000000000 +0000
+++ ./kernel/intermodule.c	2005-04-02 02:46:22.000000000 +0000
@@ -3,7 +3,7 @@
 /* Written by Keith Owens <kaos@ocs.com.au> Oct 2000 */
 #include <linux/module.h>
 #include <linux/kmod.h>
- -#include <linux/spinlock.h>
+#include <linux/rcupdate.h>
 #include <linux/list.h>
 #include <linux/slab.h>

@@ -14,7 +14,6 @@
  */

 static struct list_head ime_list = LIST_HEAD_INIT(ime_list);
- -static DEFINE_SPINLOCK(ime_lock);
 static int kmalloc_failed;

 struct inter_module_entry {
@@ -22,8 +21,17 @@ struct inter_module_entry {
 	const char *im_name;
 	struct module *owner;
 	const void *userdata;
+	struct rcu_head rcu;
 };

+static void inter_module_free(struct rcu_head *rcu)
+{
+	struct inter_module_entry *ime;
+	
+	ime = container_of(rcu, struct inter_module_entry, rcu);
+	kfree(ime);
+}
+
 /**
  * inter_module_register - register a new set of inter module data.
  * @im_name: an arbitrary string to identify the data, must be unique
@@ -36,7 +44,6 @@ struct inter_module_entry {
  */
 void inter_module_register(const char *im_name, struct module *owner, const
void *userdata)
 {
- -	struct list_head *tmp;
 	struct inter_module_entry *ime, *ime_new;

 	if (!(ime_new = kmalloc(sizeof(*ime), GFP_KERNEL))) {
@@ -52,19 +59,15 @@ void inter_module_register(const char *i
 	ime_new->owner = owner;
 	ime_new->userdata = userdata;

- -	spin_lock(&ime_lock);
- -	list_for_each(tmp, &ime_list) {
- -		ime = list_entry(tmp, struct inter_module_entry, list);
+	list_for_each_entry(ime, &ime_list, list) {
 		if (strcmp(ime->im_name, im_name) == 0) {
- -			spin_unlock(&ime_lock);
 			kfree(ime_new);
 			/* Program logic error, fatal */
 			printk(KERN_ERR "inter_module_register: duplicate im_name '%s'", im_name);
 			BUG();
 		}
 	}
- -	list_add(&(ime_new->list), &ime_list);
- -	spin_unlock(&ime_lock);
+	list_add_rcu(&ime_new->list, &ime_list);
 }

 /**
@@ -77,20 +80,15 @@ void inter_module_register(const char *i
  */
 void inter_module_unregister(const char *im_name)
 {
- -	struct list_head *tmp;
 	struct inter_module_entry *ime;

- -	spin_lock(&ime_lock);
- -	list_for_each(tmp, &ime_list) {
- -		ime = list_entry(tmp, struct inter_module_entry, list);
+	list_for_each_entry(ime, &ime_list, list) {
 		if (strcmp(ime->im_name, im_name) == 0) {
- -			list_del(&(ime->list));
- -			spin_unlock(&ime_lock);
- -			kfree(ime);
+			list_del_rcu(&(ime->list));
+			call_rcu(&ime->rcu, inter_module_free);
 			return;
 		}
 	}
- -	spin_unlock(&ime_lock);
 	if (kmalloc_failed) {
 		printk(KERN_ERR
 			"inter_module_unregister: no entry for '%s', "
@@ -115,20 +113,18 @@ void inter_module_unregister(const char
  */
 static const void *inter_module_get(const char *im_name)
 {
- -	struct list_head *tmp;
 	struct inter_module_entry *ime;
 	const void *result = NULL;

- -	spin_lock(&ime_lock);
- -	list_for_each(tmp, &ime_list) {
- -		ime = list_entry(tmp, struct inter_module_entry, list);
+	rcu_read_lock();
+	list_for_each_entry_rcu(ime, &ime_list, list) {
 		if (strcmp(ime->im_name, im_name) == 0) {
 			if (try_module_get(ime->owner))
 				result = ime->userdata;
 			break;
 		}
 	}
- -	spin_unlock(&ime_lock);
+	rcu_read_unlock();
 	return(result);
 }

@@ -158,20 +154,18 @@ const void *inter_module_get_request(con
  */
 void inter_module_put(const char *im_name)
 {
- -	struct list_head *tmp;
 	struct inter_module_entry *ime;

- -	spin_lock(&ime_lock);
- -	list_for_each(tmp, &ime_list) {
- -		ime = list_entry(tmp, struct inter_module_entry, list);
+	rcu_read_lock();
+	list_for_each_entry(ime, &ime_list, list) {
 		if (strcmp(ime->im_name, im_name) == 0) {
 			if (ime->owner)
 				module_put(ime->owner);
- -			spin_unlock(&ime_lock);
+			rcu_read_unlock();
 			return;
 		}
 	}
- -	spin_unlock(&ime_lock);
+	rcu_read_unlock();
 	printk(KERN_ERR "inter_module_put: no entry for '%s'", im_name);
 	BUG();
 }

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Re: [PATCH] RCU in kernel/intermodule.c

[Christoph Hellwig]

On Sat, Apr 02, 2005 at 11:28:12AM +0000, Luca Falavigna wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> This patch, compiled against version 2.6.12-rc1, implements RCU mechanism in
> intermodule functions.

There's no point as these functions are going to go away soon.

Re: [PATCH] RCU in kernel/intermodule.c

[Kyle Moffett]

On Apr 02, 2005, at 06:28, Luca Falavigna wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> - --- ./kernel/intermodule.c.orig	2005-04-01 19:25:26.000000000 +0000
> +++ ./kernel/intermodule.c	2005-04-02 02:46:22.000000000 +0000
> @@ -3,7 +3,7 @@
>  /* Written by Keith Owens <kaos@ocs.com.au> Oct 2000 */
>  #include <linux/module.h>
>  #include <linux/kmod.h>
> - -#include <linux/spinlock.h>

   ^ Ugh, mangled patch

> +#include <linux/rcupdate.h>
>  #include <linux/list.h>
>  #include <linux/slab.h>

Please don't sign patches with PGP, it mangles them and makes them
much harder to apply.

Also, the intermodule stuff is slated for removal, as soon as MTD and
such are fixed; the interface has been deprecated for a while.

Cheers,
Kyle Moffett

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
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L++++(+++) E W++(+) N+++(++) o? K? w--- O? M++ V? PS+() PE+(-) Y+
PGP+++ t+(+++) 5 X R? tv-(--) b++++(++) DI+ D+ G e->++++$ h!*()>++$ r  
!y?(-)
------END GEEK CODE BLOCK------

Re: [PATCH] RCU in kernel/intermodule.c

[Dave Jones]

On Sun, Apr 03, 2005 at 01:38:33PM -0400, Kyle Moffett wrote:

 > Also, the intermodule stuff is slated for removal, as soon as MTD and
 > such are fixed; the interface has been deprecated for a while.

Actually 'just' mtd now iirc. agpgart was the penultimate user which
got fixed a few months back.

		Dave

Re: [PATCH] RCU in kernel/intermodule.c

[Pete Zaitcev]

On Sat, 02 Apr 2005 11:28:12 +0000 Luca Falavigna <dktrkranz@gmail.com> wrote:

> This patch, compiled against version 2.6.12-rc1, implements RCU mechanism in
> intermodule functions.

This sounds like a pure and unmitigated insanity to me. Please tell us
why in the world you wanted to do this.

-- Pete