From: Miroslav Benes <mbenes@suse.cz>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jessica Yu <jeyu@redhat.com>, Seth Jennings <sjenning@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Vojtech Pavlik <vojtech@suse.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] livepatch/module: remove livepatch module notifier
Date: Fri, 5 Feb 2016 09:59:17 +0100 (CET) [thread overview]
Message-ID: <alpine.LNX.2.00.1602050958260.25516@pobox.suse.cz> (raw)
In-Reply-To: <20160204205511.GO22854@treble.redhat.com>
On Thu, 4 Feb 2016, Josh Poimboeuf wrote:
> On Mon, Feb 01, 2016 at 08:17:36PM -0500, Jessica Yu wrote:
> > Remove the livepatch module notifier in favor of directly enabling and
> > disabling patches to modules in the module loader. Hard-coding the
> > function calls ensures that ftrace_module_enable() is run before
> > klp_module_enable() during module load, and that klp_module_disable() is
> > run before ftrace_release_mod() during module unload. This way, ftrace
> > and livepatch code is run in the correct order during the module
> > load/unload sequence without dependence on the module notifier call chain.
> >
> > This fixes a notifier ordering issue in which the ftrace module notifier
> > (and hence ftrace_module_enable()) for coming modules was being called
> > after klp_module_notify(), which caused livepatch modules to initialize
> > incorrectly.
> >
> > Signed-off-by: Jessica Yu <jeyu@redhat.com>
> > ---
> > include/linux/livepatch.h | 9 +++
> > kernel/livepatch/core.c | 144 ++++++++++++++++++++++------------------------
> > kernel/module.c | 8 +++
> > 3 files changed, 86 insertions(+), 75 deletions(-)
> >
> > diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
> > index a882865..fdd5f1c 100644
> > --- a/include/linux/livepatch.h
> > +++ b/include/linux/livepatch.h
> > @@ -134,6 +134,15 @@ int klp_unregister_patch(struct klp_patch *);
> > int klp_enable_patch(struct klp_patch *);
> > int klp_disable_patch(struct klp_patch *);
> >
> > +/* Called from the module loader during module coming/going states */
> > +extern int klp_module_enable(struct module *mod);
> > +extern void klp_module_disable(struct module *mod);
> > +
> > +#else /* !CONFIG_LIVEPATCH */
> > +
> > +static inline int klp_module_enable(struct module *mod) { return 0; }
> > +static inline void klp_module_disable(struct module *mod) { }
> > +
> > #endif /* CONFIG_LIVEPATCH */
> >
> > #endif /* _LINUX_LIVEPATCH_H_ */
> > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> > index bc2c85c..7aa975d 100644
> > --- a/kernel/livepatch/core.c
> > +++ b/kernel/livepatch/core.c
> > @@ -103,7 +103,7 @@ static void klp_find_object_module(struct klp_object *obj)
> > */
> > mod = find_module(obj->name);
> > /*
> > - * Do not mess work of the module coming and going notifiers.
> > + * Do not mess work of the klp module coming and going handlers.
> > * Note that the patch might still be needed before the going handler
> > * is called. Module functions can be called even in the GOING state
> > * until mod->exit() finishes. This is especially important for
> > @@ -866,103 +866,107 @@ int klp_register_patch(struct klp_patch *patch)
> > }
> > EXPORT_SYMBOL_GPL(klp_register_patch);
> >
> > -static int klp_module_notify_coming(struct klp_patch *patch,
> > - struct klp_object *obj)
> > +/* Called when module state is MODULE_STATE_COMING */
> > +int klp_module_enable(struct module *mod)
>
> I think this function name was originally my idea. But now I'm thinking
> it could cause some confusion with the similarly named
> klp_enable_object().
>
> How about naming it klp_module_coming()? That more accurately describes
> its purpose IMO and it would also make the comment above it no longer
> necessary.
>
> And similarly we could rename klp_module_disable() ->
> klp_module_going().
I agree. klp_module_{coming,going} is better.
Miroslav
next prev parent reply other threads:[~2016-02-05 8:59 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-02 1:17 [PATCH v2 0/2] Fix ordering of ftrace/livepatch calls on module load and unload Jessica Yu
2016-02-02 1:17 ` [PATCH v2 1/2] ftrace/module: remove ftrace module notifier Jessica Yu
2016-02-04 13:27 ` Petr Mladek
2016-02-04 14:18 ` Steven Rostedt
2016-02-04 15:21 ` Petr Mladek
2016-02-04 15:33 ` Steven Rostedt
2016-02-02 1:17 ` [PATCH v2 2/2] livepatch/module: remove livepatch " Jessica Yu
2016-02-04 14:39 ` Petr Mladek
2016-02-04 14:56 ` Steven Rostedt
2016-02-04 16:47 ` Miroslav Benes
2016-02-05 4:11 ` Jessica Yu
2016-02-05 9:15 ` Miroslav Benes
2016-02-05 10:06 ` Petr Mladek
2016-02-08 0:34 ` Rusty Russell
2016-02-04 17:29 ` [PATCH v2 2/2] " Miroslav Benes
2016-02-04 20:55 ` Josh Poimboeuf
2016-02-05 8:59 ` Miroslav Benes [this message]
2016-02-04 10:43 ` [PATCH v2 0/2] Fix ordering of ftrace/livepatch calls on module load and unload Jiri Kosina
2016-02-04 13:29 ` Steven Rostedt
2016-02-05 1:17 ` Rusty Russell
-- strict thread matches above, loose matches on Subject: below --
2016-03-11 20:03 [PATCH v2 0/2] Livepatch module notifier cleanup Jessica Yu
2016-03-11 20:03 ` [PATCH v2 2/2] livepatch/module: remove livepatch module notifier Jessica Yu
2016-03-14 15:06 ` Petr Mladek
2016-03-14 20:01 ` Josh Poimboeuf
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