linux-kernel - Re: [PATCH v3 2/3] module: Add lock_modules() and unlock

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Date:   Thu, 16 Jul 2020 20:37:34 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     linux-kernel@...r.kernel.org, x86@...r.kernel.org,
        Andi Kleen <ak@...ux.intel.com>, Jessica Yu <jeyu@...nel.org>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        "open list:LIVE PATCHING" <live-patching@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] module: Add lock_modules() and unlock_modules()

On Wed, Jul 15, 2020 at 05:39:39PM +0900, Masami Hiramatsu wrote:
> On Wed, 15 Jul 2020 01:32:28 +0300
> Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> wrote:
> 
> > Add wrappers to take the modules "big lock" in order to encapsulate
> > conditional compilation (CONFIG_MODULES) inside the wrapper.
> > 
> > Cc: Andi Kleen <ak@...ux.intel.com>
> > Suggested-by: Masami Hiramatsu <mhiramat@...nel.org>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > ---
> >  include/linux/module.h      | 15 ++++++++++
> >  kernel/kprobes.c            |  4 +--
> >  kernel/livepatch/core.c     |  8 ++---
> >  kernel/module.c             | 60 ++++++++++++++++++-------------------
> >  kernel/trace/trace_kprobe.c |  4 +--
> >  5 files changed, 53 insertions(+), 38 deletions(-)
> > 
> > diff --git a/include/linux/module.h b/include/linux/module.h
> > index 2e6670860d27..857b84bf9e90 100644
> > --- a/include/linux/module.h
> > +++ b/include/linux/module.h
> > @@ -902,4 +902,19 @@ static inline bool module_sig_ok(struct module *module)
> >  }
> >  #endif	/* CONFIG_MODULE_SIG */
> >  
> > +#ifdef CONFIG_MODULES
> > +static inline void lock_modules(void)
> > +{
> > +	mutex_lock(&module_mutex);
> > +}
> > +
> > +static inline void unlock_modules(void)
> > +{
> > +	mutex_unlock(&module_mutex);
> > +}
> > +#else
> > +static inline void lock_modules(void) { }
> > +static inline void unlock_modules(void) { }
> > +#endif
> 
> You don't need to add new #ifdefs. There is a room for dummy prototypes
> for !CONFIG_MODULES already in modules.h.
> 
> -----
> struct notifier_block;
> 
> #ifdef CONFIG_MODULES
> 
> extern int modules_disabled; /* for sysctl */
> 
> ...
> #else /* !CONFIG_MODULES... */
> 
> static inline struct module *__module_address(unsigned long addr)
> {
> -----
> 
> So you can just put those inlines in the appropriate places ;)
> 
> Thank you,

Rrright.

/Jarkko