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From: "Tobin C. Harding" <me@tobin.cc>
To: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Tobin C. Harding" <tobin@kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 5/5] livepatch: Do not manually track kobject initialization
Date: Thu, 2 May 2019 18:31:27 +1000	[thread overview]
Message-ID: <20190502083127.GC18363@eros.localdomain> (raw)
In-Reply-To: <20190502073044.bfzugymrncnaajxe@pathway.suse.cz>

On Thu, May 02, 2019 at 09:30:44AM +0200, Petr Mladek wrote:
> On Thu 2019-05-02 09:12:32, Greg Kroah-Hartman wrote:
> > On Thu, May 02, 2019 at 12:31:42PM +1000, Tobin C. Harding wrote:
> > > Currently we use custom logic to track kobject initialization.  Recently
> > > a predicate function was added to the kobject API so we now no longer
> > > need to do this.
> > > 
> > > Use kobject API to check for initialized state of kobjects instead of
> > > using custom logic to track state.
> > > 
> > > Signed-off-by: Tobin C. Harding <tobin@kernel.org>
> > > ---
> > >  include/linux/livepatch.h |  6 ------
> > >  kernel/livepatch/core.c   | 18 +++++-------------
> > >  2 files changed, 5 insertions(+), 19 deletions(-)
> > > 
> > > @@ -626,7 +626,7 @@ static void __klp_free_objects(struct klp_patch *patch, bool nops_only)
> > >  		list_del(&obj->node);
> > >  
> > >  		/* Might be called from klp_init_patch() error path. */
> > > -		if (obj->kobj_added) {
> > > +		if (kobject_is_initialized(&obj->kobj)) {
> > >  			kobject_put(&obj->kobj);
> > >  		} else if (obj->dynamic) {
> > >  			klp_free_object_dynamic(obj);
> > 
> > Same here, let's not be lazy.
> > 
> > The code should "know" if the kobject has been initialized or not
> > because it is the entity that asked for it to be initialized.  Don't add
> > extra logic to the kobject core (like the patch before this did) just
> > because this one subsystem wanted to only write 1 "cleanup" function.
> 
> We use kobject for a mix of statically and dynamically defined
> structures[*]. And we misunderstood the behavior of kobject_init().
> 
> Anyway, the right solution is to call kobject_init()
> already in klp_init_patch_early() for the statically
> defined structures and in klp_alloc*() for the dynamically
> allocated ones. Then we could simply call kobject_put()
> every time.
> 
> Tobin, this goes deeper into the livepatching code that
> you probably expected. Do you want to do the above
> suggested change or should I prepare the patch?

I'd love for you to handle this one Petr, I'd say its a net gain
time wise that way since if I do it you'll have to review it too
carefully anyways.

So that will mean patch #1 and #5 of this series are dropped and handed
off to you (thanks).  Patch #2 and #3 Greg said he will take.  Patch #4
is not needed.  That's a win in my books :)

Thanks,
Tobin.

  parent reply	other threads:[~2019-05-02  8:32 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-02  2:31 [RFC PATCH 0/5] kobject: Add and use init predicate Tobin C. Harding
2019-05-02  2:31 ` [RFC PATCH 1/5] livepatch: Fix kobject memleak Tobin C. Harding
2019-05-02  7:22   ` Greg Kroah-Hartman
2019-05-02  8:46   ` Petr Mladek
2019-05-02  2:31 ` [RFC PATCH 2/5] kobject: Remove docstring reference to kset Tobin C. Harding
2019-05-02  7:20   ` Greg Kroah-Hartman
2019-05-02  2:31 ` [RFC PATCH 3/5] kobject: Fix kernel-doc comment first line Tobin C. Harding
2019-05-02  7:20   ` Greg Kroah-Hartman
2019-05-02  7:38   ` Johan Hovold
2019-05-02  8:25     ` Tobin C. Harding
2019-05-02  8:39       ` Johan Hovold
2019-05-03  1:40         ` Tobin C. Harding
2019-05-03  1:46           ` Randy Dunlap
2019-05-03 12:23             ` Jonathan Corbet
2019-05-03  7:56           ` Johan Hovold
2019-05-03  8:05             ` Petr Mladek
2019-05-06 23:00             ` Tobin C. Harding
2019-05-07  9:38               ` Johan Hovold
2019-05-02  2:31 ` [RFC PATCH 4/5] kobject: Add kobject initialized predicate Tobin C. Harding
2019-05-02  2:31 ` [RFC PATCH 5/5] livepatch: Do not manually track kobject initialization Tobin C. Harding
2019-05-02  7:12   ` Greg Kroah-Hartman
2019-05-02  7:30     ` Petr Mladek
2019-05-02  7:42       ` Greg Kroah-Hartman
2019-05-02  8:31       ` Tobin C. Harding [this message]
2019-05-02  8:51         ` Petr Mladek
2019-05-02 11:42 ` [RFC PATCH 0/5] kobject: Add and use init predicate Miroslav Benes

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