linux-kernel - Re: [PATCH 1/2] livepatch: Remove custom kobject state handling

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Message-ID: <alpine.LSU.2.21.1905071355430.7486@pobox.suse.cz>
Date:   Tue, 7 May 2019 14:32:57 +0200 (CEST)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Petr Mladek <pmladek@...e.com>
cc:     Jiri Kosina <jikos@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
        "Tobin C . Harding" <tobin@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] livepatch: Remove custom kobject state handling

On Fri, 3 May 2019, Petr Mladek wrote:

> kobject_init() always succeeds and sets the reference count to 1.
> It allows to always free the structures via kobject_put() and
> the related release callback.
> 
> Note that the custom kobject state handling was used only
> because we did not know that kobject_put() can and actually
> should get called even when kobject_init_and_add() fails.
> 
> The patch should not change the existing behavior.

Pity that the changelog does not describe the change from 
kobject_init_and_add() to two-stage kobject init (separate kobject_init() 
and kobject_add()).

Petr changed it, because now each member of new dynamic lists (created in 
klp_init_patch_early()) is initialized with kobject_init(), so we do not 
have to worry about calling kobject_put() (this is slightly different from 
kobj_added).

It would also be possible to retain kobject_init_and_add() and move it to 
klp_init_patch_early(), but it would be uglier in my opinion.

Miroslav