Re: [PATCH v2] jump_label: fix jump_label update

[Jiri Olsa <jolsa@redhat.com>]

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");