linux-kernel - Re: [PATCH v5 3/3] livepatch: add transition notices

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Message-ID: <20170927114908.GM21048@pathway.suse.cz>
Date:   Wed, 27 Sep 2017 13:49:08 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Joe Lawrence <joe.lawrence@...hat.com>
Cc:     live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jessica Yu <jeyu@...nel.org>, Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Chris J Arges <chris.j.arges@...onical.com>
Subject: Re: [PATCH v5 3/3] livepatch: add transition notices

On Thu 2017-08-31 10:53:53, Joe Lawrence wrote:
> Log a few kernel debug messages at the beginning of the following livepatch
> transition functions:
> 
>   klp_complete_transition()
>   klp_cancel_transition()
>   klp_init_transition()
>   klp_reverse_transition()
> 
> Also update the log notice message in klp_start_transition() for similar
> verbiage as the above messages.
> 
> Suggested-by: Josh Poimboeuf <jpoimboe@...hat.com>
> Signed-off-by: Joe Lawrence <joe.lawrence@...hat.com>
> ---
>  kernel/livepatch/transition.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
> index 53887f0bca10..3d44a3cf27be 100644
> --- a/kernel/livepatch/transition.c
> +++ b/kernel/livepatch/transition.c
> @@ -82,6 +82,10 @@ static void klp_complete_transition(void)
>  	unsigned int cpu;
>  	bool immediate_func = false;
>  
> +	pr_debug("'%s': completing %s transition\n",
> +		 klp_transition_patch->mod->name,
> +		 klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
> +
>  	if (klp_target_state == KLP_UNPATCHED) {
>  		/*
>  		 * All tasks have transitioned to KLP_UNPATCHED so we can now
> @@ -163,6 +167,9 @@ void klp_cancel_transition(void)
>  	if (WARN_ON_ONCE(klp_target_state != KLP_PATCHED))
>  		return;
>  
> +	pr_debug("'%s': canceling transition, unpatching\n",

This sentence is a bit confusing. It is related to the Mirek's concern
about that the following message would be "completing unpatching transition".

What about using something like:

	pr_debug("'%s': canceling patching transition, going to unpatch\n",


Best Regards,
Petr