linux-kernel - Re: [PATCH v15 04/11] livepatch: Don't block the removal of patches loaded after a forced transition

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Message-ID: <alpine.LSU.2.21.1901091549310.12972@pobox.suse.cz>
Date:   Wed, 9 Jan 2019 15:50:09 +0100 (CET)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Petr Mladek <pmladek@...e.com>
cc:     Jiri Kosina <jikos@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jason Baron <jbaron@...mai.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Evgenii Shatokhin <eshatokhin@...tuozzo.com>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v15 04/11] livepatch: Don't block the removal of patches
 loaded after a forced transition

On Wed, 9 Jan 2019, Petr Mladek wrote:

> module_put() is currently never called in klp_complete_transition() when
> klp_force is set. As a result, we might keep the reference count even when
> klp_enable_patch() fails and klp_cancel_transition() is called.
> 
> This might give the impression that a module might get blocked in some
> strange init state. Fortunately, it is not the case. The reference count
> is ignored when mod->init fails and erroneous modules are always removed.
> 
> Anyway, this might be confusing. Instead, this patch moves
> the global klp_forced flag into struct klp_patch. As a result,
> we block only modules that might still be in use after a forced
> transition. Newly loaded livepatches might be eventually completely
> removed later.
> 
> It is not a big deal. But the code is at least consistent with
> the reality.
> 
> Signed-off-by: Petr Mladek <pmladek@...e.com>
> Acked-by: Joe Lawrence <joe.lawrence@...hat.com>

Acked-by: Miroslav Benes <mbenes@...e.cz>

Miroslav