Re: [PATCH v2] jump_label: fix jump_label update

Jiri Olsa
2011-06-21T09:45:25Z

On Tue, Jun 21, 2011 at 10:35:55AM +0800, Xiao Guangrong wrote:
> The key of module is out of __stop___jump_table, it causes the events
> of modules does not work
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
> kernel/jump_label.c | 14 +++++++++-----
> 1 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/jump_label.c b/kernel/jump_label.c
> index fa27e75..a8ce450 100644
> --- a/kernel/jump_label.c
> +++ b/kernel/jump_label.c
> @@ -375,15 +375,19 @@ int jump_label_text_reserved(void *start, void *end)
>
> static void jump_label_update(struct jump_label_key *key, int enable)
> {
> - struct jump_entry *entry = key->entries;
> -
> - /* if there are no users, entry can be NULL */
> - if (entry)
> - __jump_label_update(key, entry, __stop___jump_table, enable);
> + struct jump_entry *entry = key->entries, *stop = __stop___jump_table;
>
> #ifdef CONFIG_MODULES
> + struct module *mod = __module_address((jump_label_t)key);
> +
> __jump_label_mod_update(key, enable);
> +
> + if (mod)
> + stop = mod->jump_entries + mod->num_jump_entries;
> #endif
> + /* if there are no users, entry can be NULL */
> + if (entry)
> + __jump_label_update(key, entry, stop, enable);
> }
>
> #endif
> --
> 1.7.5.4

That works for me, but in order to test it I needed to export
jump_label_inc/jump_label_dec functions.

Not sure I'm missing something, but to manage a key that is local
to the module, we need to call jump_label_inc/jump_label_dec
from within the module code, so we need some of the jump_label
functions exported.. it'd be probably:

jump_label_inc/jump_label_dec/jump_label_enabled

wbr,
jirka

I used following module code to test:
---
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/jump_label.h>

static struct jump_label_key key;

static bool enabled;
module_param(enabled, bool, 0644);

static int __init mod_init(void)
{
if (enabled)
jump_label_inc(&key);

if (static_branch(&key))
printk("key enabled\n");
else
printk("key disabled\n");

if (jump_label_enabled(&key))
printk("key enabled1\n");
else
printk("key disabled1\n");

printk("mod loaded\n");
return 0;
}

static void __exit mod_exit(void)
{
printk("mod unloaded\n");
return;
}

module_init(mod_init);
module_exit(mod_exit);
MODULE_LICENSE("GPL");