linux-kernel - Re: [PATCHv2] refcount: always allow checked forms

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Message-ID: <CAGXu5j+hfVmB_+wPn=-hx3w+sNoKQBRLAbf2M0WrNY3Y+tYCQQ@mail.gmail.com>
Date:   Thu, 12 Jul 2018 12:50:54 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Will Deacon <will.deacon@....com>
Cc:     Mark Rutland <mark.rutland@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        David Sterba <dsterba@...e.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCHv2] refcount: always allow checked forms

On Thu, Jul 12, 2018 at 10:01 AM, Will Deacon <will.deacon@....com> wrote:
> On Wed, Jul 11, 2018 at 10:36:07AM +0100, Mark Rutland wrote:
>> In many cases, it would be useful to be able to use the full
>> sanity-checked refcount helpers regardless of CONFIG_REFCOUNT_FULL, as
>> this would help to avoid duplicate warnings where callers try to
>> sanity-check refcount manipulation.
>>
>> This patch refactors things such that the full refcount helpers were
>> always built, as refcount_${op}_checked(), such that they can be used
>> regardless of CONFIG_REFCOUNT_FULL. This will allow code which *always*
>> wants a checked refcount to opt-in, avoiding the need to duplicate the
>> logic for warnings.
>>
>> There should be no functional change as a result of this patch.
>>
>> Signed-off-by: Mark Rutland <mark.rutland@....com>
>> Acked-by: Kees Cook <keescook@...omium.org>
>> Reviewed-by: David Sterba <dsterba@...e.com>
>> Cc: Boqun Feng <boqun.feng@...il.com>
>> Cc: Ingo Molnar <mingo@...nel.org>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Cc: Will Deacon <will.deacon@....com>
>> ---
>>  include/linux/refcount.h | 27 +++++++++++++++++-------
>>  lib/refcount.c           | 53 +++++++++++++++++++++++-------------------------
>>  2 files changed, 45 insertions(+), 35 deletions(-)
>
> Looks good to me:
>
> Acked-by: Will Deacon <will.deacon@....com>

Peter, Ingo, can this go via the atomics tree? That's been the
traditional location for the refcount patches.

Thanks!

-Kees

-- 
Kees Cook
Pixel Security