linux-kernel - Re: [PATCH 3/3] thread_info: include <current.h> for THREAD_INFO_IN

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Message-ID: <CALCETrUqApnWBwFPwkToTp1_Wm68tbPAW=UH+X5mZrNS+3rHjA@mail.gmail.com>
Date:   Thu, 27 Oct 2016 16:13:49 -0700
From:   Andy Lutomirski <luto@...capital.net>
To:     Mark Rutland <mark.rutland@....com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Kees Cook <keescook@...omium.org>,
        Andrew Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 3/3] thread_info: include <current.h> for THREAD_INFO_IN_TASK

On Wed, Oct 19, 2016 at 11:28 AM, Mark Rutland <mark.rutland@....com> wrote:
> When CONFIG_THREAD_INFO_IN_TASK is selected, the current_thread_info()
> macro relies on current having been defined prior to its use. However,
> not all users of current_thread_info() include <asm/current.h>, and thus
> current is not guaranteed to be defined.
>
> When CONFIG_THREAD_INFO_IN_TASK is not selected, it's possible that
> get_current() / current are based upon current_thread_info(), and
> <asm/current.h> includes <asm/thread_info.h>. Thus always including
> <asm/current.h> would result in circular dependences on some platforms.
>
> To ensure both cases work, this patch includes <asm/current.h>, but only
> when CONFIG_THREAD_INFO_IN_TASK is selected.

Reviewed-by: Andy Lutomirski <luto@...nel.org>

although it would be nice if you moved your description of why the
include is conditional into a comment.

--Andy