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Date:   Thu, 6 Oct 2022 16:27:31 -0700
From:   Kees Cook <keescook@chromium.org>
To:     "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc:     linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        kernel-dev@igalia.com, kernel@gpiccoli.net, anton@enomsg.org,
        ccross@android.com, tony.luck@intel.com
Subject: Re: [PATCH 1/8] pstore: Improve error reporting in case of backend
 overlap
Message-ID: <202210061627.E29FCDBE1@keescook>
References: <20221006224212.569555-1-gpiccoli@igalia.com>
 <20221006224212.569555-2-gpiccoli@igalia.com>
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On Thu, Oct 06, 2022 at 07:42:05PM -0300, Guilherme G. Piccoli wrote:
> The pstore infrastructure supports one single backend at a time;
> trying to load a another backend causes an error and displays a
> message, introduced on commit 0d7cd09a3dbb ("pstore: Improve
> register_pstore() error reporting").
> 
> Happens that this message is not really clear about the situation,
> also the current error returned (-EPERM) isn't accurate, whereas
> -EBUSY makes more sense. We have another place in the code that
> relies in the -EBUSY return for a similar check.
> 
> So, make it consistent here by returning -EBUSY and using a
> similar message in both scenarios.
> 
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
> ---
>  fs/pstore/platform.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 0c034ea39954..c32957e4b256 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -562,8 +562,9 @@ static int pstore_write_user_compat(struct pstore_record *record,
>  int pstore_register(struct pstore_info *psi)
>  {
>  	if (backend && strcmp(backend, psi->name)) {
> -		pr_warn("ignoring unexpected backend '%s'\n", psi->name);
> -		return -EPERM;
> +		pr_warn("backend '%s' already in use: ignoring '%s'\n",
> +			backend, psi->name);
> +		return -EBUSY;

Thank you! Yes, this has bothered me for a while. :)

-- 
Kees Cook