linux-kernel - Re: [PATCH 1/2] xen: correct error handling in xen-acpi-processor

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Date:   Fri, 31 Mar 2017 10:10:50 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Cc:     konrad.wilk@...cle.com, stable@...r.kernel.org
Subject: Re: [PATCH 1/2] xen: correct error handling in xen-acpi-processor

On 03/31/2017 07:19 AM, Juergen Gross wrote:
> Error handling in upload_pm_data() is rather questionable: possible
> errno values from called functions are or'ed together resulting in
> strange return values: -EINVAL and -ENOMEM would e.g. result in
> returning -EXDEV.

And it doesn't matter anyway since noone checks return value. (not that
OR-ing errors makes much sense)

>
> Fix this by bailing out early after the first error.

I am not sure about this: why should we not try to load P states if C
states failed to load?

-boris

>
> Cc: stable@...r.kernel.org
> Signed-off-by: Juergen Gross <jgross@...e.com>
> ---
>  drivers/xen/xen-acpi-processor.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/xen/xen-acpi-processor.c b/drivers/xen/xen-acpi-processor.c
> index 23e391d..3659ed3 100644
> --- a/drivers/xen/xen-acpi-processor.c
> +++ b/drivers/xen/xen-acpi-processor.c
> @@ -283,8 +283,8 @@ static int upload_pm_data(struct acpi_processor *_pr)
>  	if (_pr->flags.power)
>  		err = push_cxx_to_hypervisor(_pr);
>  
> -	if (_pr->performance && _pr->performance->states)
> -		err |= push_pxx_to_hypervisor(_pr);
> +	if (!err && _pr->performance && _pr->performance->states)
> +		err = push_pxx_to_hypervisor(_pr);
>  
>  	mutex_unlock(&acpi_ids_mutex);
>  	return err;