Re: ftrace/module: Move ftrace_release_mod to ddebug_cleanup label

[Jessica Yu]

+++ Steven Rostedt [28/12/17 11:32 -0500]:
> Jessica,
>
> Can you take this patch. You can add:
>
> Reviewed-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>

Sure, thanks Steven.

Namit, your patch does not apply cleanly to modules-next nor
linux-next. It looks like you based your patch on an old tree?
(e.g., we got rid of the module_core and core_size fields a few years
ago...) Could you please rebase your patch on linux-next and resend? 

Thanks,

Jessica

> On Tue, 12 Dec 2017 17:24:32 +0530
> Namit Gupta <gupta.namit@xxxxxxxxxxx> wrote:
>
> > ftrace_module_init happen after dynamic_debug_setup, it is desired that
> > cleanup should be called after this label however in current implementation
> > it is called in free module label,ie:even though ftrace in not initialized,
> > from so many fail case ftrace_release_mod() will be called and unnecessary
> > traverse the whole list.
> > In below patch we moved ftrace_release_mod() from free_module label to
> > ddebug_cleanup label. that is the best possible location, other solution
> > is to make new label to ftrace_release_mod() but since ftrace_module_init()
> > is not return with minimum changes it should be in ddebug_cleanup label.
> >
> >
> > Signed-off-by: Namit Gupta <gupta.namit@xxxxxxxxxxx>
> >
> > ---
> >  kernel/module.c | 7 +------
> >  1 file changed, 1 insertion(+), 6 deletions(-)
> >
> > diff --git a/kernel/module.c b/kernel/module.c
> > index 0d1cb8d..4be966a 100644
> > --- a/kernel/module.c
> > +++ b/kernel/module.c
> > @@ -3523,6 +3523,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
> >  	unset_module_core_ro_nx(mod);
> >
> >   ddebug_cleanup:
> > +	ftrace_release_mod(mod);
> >  	dynamic_debug_remove(info->debug);
> >  	synchronize_sched();
> >  	kfree(mod->args);
> > @@ -3541,12 +3542,6 @@ static int load_module(struct load_info *info, const char __user *uargs,
> >  	synchronize_rcu();
> >  	mutex_unlock(&module_mutex);
> >   free_module:
> > -	/*
> > -	 * Ftrace needs to clean up what it initialized.
> > -	 * This does nothing if ftrace_module_init() wasn't called,
> > -	 * but it must be called outside of module_mutex.
> > -	 */
> > -	ftrace_release_mod(mod);
> >  	/* Free lock-classes; relies on the preceding sync_rcu() */
> >  	lockdep_free_key_range(mod->module_core, mod->core_size);