[PATCH v2] jump_label: fix jump_label update

[PATCH v2] jump_label: fix jump_label update

[Xiao Guangrong]

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

Re: [PATCH v2] jump_label: fix jump_label update

[Jiri Olsa]

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");

Re: [PATCH v2] jump_label: fix jump_label update

[Jason Baron]

On Tue, Jun 21, 2011 at 11:44:55AM +0200, Jiri Olsa wrote:
> 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
> 

You're not missing anything, right now all the enabling/disabling is
done in the core kernel, hence no need for the export. I'd prefer to
keep them non-exported until we had a real use-case that required them
to be exported. But I don't feel that strongly about it.

Thanks,

-Jason

Re: [PATCH v2] jump_label: fix jump_label update

[Jason Baron]

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

Looks good. Thanks for the fix!

Acked-by: Jason Baron <jbaron@redhat.com>

-Jason

Re: [PATCH v2] jump_label: fix jump_label update

[Avi Kivity]

On 06/21/2011 05:35 AM, Xiao Guangrong wrote:
> The key of module is out of __stop___jump_table, it causes the events
> of modules does not work
>

What's the status of this patch?  I'm affected by this as well (I'm 
guessing the same module is involved).  I'm near the end of a bisect, 
but there's probably no point given this patch.

-- 
error compiling committee.c: too many arguments to function

Re: [PATCH v2] jump_label: fix jump_label update

[Avi Kivity]

On 06/23/2011 03:22 PM, Avi Kivity wrote:
> On 06/21/2011 05:35 AM, Xiao Guangrong wrote:
>> The key of module is out of __stop___jump_table, it causes the events
>> of modules does not work
>>
>
> What's the status of this patch? 

Oh, it's just two days out.  Didn't mean to sound impatient.

> I'm affected by this as well (I'm guessing the same module is 
> involved).  I'm near the end of a bisect, but there's probably no 
> point given this patch.
>

I can confirm it fixes my issue.

Tested-by: Avi Kivity <avi@redhat.com>

-- 
error compiling committee.c: too many arguments to function

Re: [PATCH v2] jump_label: fix jump_label update

[Steven Rostedt]

On Thu, 2011-06-23 at 15:45 +0300, Avi Kivity wrote:
> On 06/23/2011 03:22 PM, Avi Kivity wrote:
> > On 06/21/2011 05:35 AM, Xiao Guangrong wrote:
> >> The key of module is out of __stop___jump_table, it causes the events
> >> of modules does not work
> >>
> >
> > What's the status of this patch? 
> 
> Oh, it's just two days out.  Didn't mean to sound impatient.

I've been working on other things than tracing lately.

> 
> > I'm affected by this as well (I'm guessing the same module is 
> > involved).  I'm near the end of a bisect, but there's probably no 
> > point given this patch.
> >
> 
> I can confirm it fixes my issue.
> 
> Tested-by: Avi Kivity <avi@redhat.com>
> 

Thanks, I'll queue it up for 3.0 and start my tests on it.

-- Steve

[tip:perf/urgent] jump_label: Fix jump_label update for modules

[tip-bot for Xiao Guangrong]

Commit-ID:  140fe3b1ab9c082182ef13359fab4ddba95c24c3
Gitweb:     http://git.kernel.org/tip/140fe3b1ab9c082182ef13359fab4ddba95c24c3
Author:     Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
AuthorDate: Tue, 21 Jun 2011 10:35:55 +0800
Committer:  Steven Rostedt <rostedt@goodmis.org>
CommitDate: Wed, 29 Jun 2011 09:59:17 -0400

jump_label: Fix jump_label update for modules

The jump labels entries for modules do not stop at __stop__jump_table,
but after mod->jump_entries + mod_num_jump_entries.

By checking the wrong end point, module trace events never get enabled.

Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Tested-by: Avi Kivity <avi@redhat.com>
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Link: http://lkml.kernel.org/r/4E00038B.2060404@cn.fujitsu.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 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