linux-kernel - Re: [PATCH] kernel/irq: Limit validation of cpumask_var_t to CONFIG_CPUMASK

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Message-ID: <20170412164337.GF28657@google.com>
Date:   Wed, 12 Apr 2017 09:43:37 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org,
        Grant Grundler <grundler@...omium.org>,
        Greg Hackmann <ghackmann@...gle.com>,
        Michael Davidson <md@...gle.com>
Subject: Re: [PATCH] kernel/irq: Limit validation of cpumask_var_t to
 CONFIG_CPUMASK_OFFSTACK=y

Hi Thomas,

El Wed, Apr 12, 2017 at 09:23:58AM +0200 Thomas Gleixner ha dit:

> On Tue, 11 Apr 2017, Matthias Kaehlcke wrote:
> > With CONFIG_CPUMASK_OFFSTACK=y cpumask_var_t is a struct cpumask
> > pointer, otherwise a struct cpumask array with a single element.
> > 
> > irq_thread_check_affinity() validates the cpumask_var_t field in the
> > interrupt descriptor by checking if it is not NULL. This works for
> > both CONFIG_CPUMASK_OFFSTACK=y/n, however clang raises the following
> > warning with CONFIG_CPUMASK_OFFSTACK=n:
> > 
> > kernel/irq/manage.c:839:28: error: address of array
> > 'desc->irq_common_data.affinity' will always evaluate to 'true'
> > [-Werror,-Wpointer-bool-conversion]
> > 
> > To get rid of the warning only validate the cpumask_var_t field when
> > CONFIG_CPUMASK_OFFSTACK=y.
> 
> This ifdeffery is horrible. Can you please create a helper inline
> cpumask_available() or something like that which hides this in a header
> file. The irq code is probably not the only place which does this.

Thanks for your comments, I'll rework the patch to use a helper
instead.

Cheers

Matthias