From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>,
Ingo Molnar <mingo@kernel.org>,
Elena Reshetova <elena.reshetova@intel.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Hanjun Guo <guohanjun@huawei.com>,
Jan Glauber <jglauber@marvell.com>
Subject: Re: [PATCH v2 0/6] Rework REFCOUNT_FULL using atomic_fetch_* operations
Date: Wed, 28 Aug 2019 09:30:52 +0200 [thread overview]
Message-ID: <20190828073052.GL2332@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190827163204.29903-1-will@kernel.org>
On Tue, Aug 27, 2019 at 05:31:58PM +0100, Will Deacon wrote:
> Will Deacon (6):
> lib/refcount: Define constants for saturation and max refcount values
> lib/refcount: Ensure integer operands are treated as signed
> lib/refcount: Remove unused refcount_*_checked() variants
> lib/refcount: Move bulk of REFCOUNT_FULL implementation into header
> lib/refcount: Improve performance of generic REFCOUNT_FULL code
> lib/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions
So I'm not a fan; I itch at the whole racy nature of this thing and I
find the code less than obvious. Yet, I have to agree it is exceedingly
unlikely the race will ever actually happen, I just don't want to be the
one having to debug it.
I've not looked at the implementation much; does it do all the same
checks the FULL one does? The x86-asm one misses a few iirc, so if this
is similarly fast but has all the checks, it is in fact better.
Can't we make this a default !FULL implementation?
next prev parent reply other threads:[~2019-08-28 7:31 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-27 16:31 [PATCH v2 0/6] Rework REFCOUNT_FULL using atomic_fetch_* operations Will Deacon
2019-08-27 16:31 ` [PATCH v2 1/6] lib/refcount: Define constants for saturation and max refcount values Will Deacon
2019-08-27 16:32 ` [PATCH v2 2/6] lib/refcount: Ensure integer operands are treated as signed Will Deacon
2019-08-27 16:32 ` [PATCH v2 3/6] lib/refcount: Remove unused refcount_*_checked() variants Will Deacon
2019-08-27 16:32 ` [PATCH v2 4/6] lib/refcount: Move bulk of REFCOUNT_FULL implementation into header Will Deacon
2019-08-27 16:32 ` [PATCH v2 5/6] lib/refcount: Improve performance of generic REFCOUNT_FULL code Will Deacon
2019-08-27 16:32 ` [PATCH v2 6/6] lib/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions Will Deacon
2019-08-27 17:51 ` [PATCH v2 0/6] Rework REFCOUNT_FULL using atomic_fetch_* operations Kees Cook
2019-08-28 7:30 ` Peter Zijlstra [this message]
2019-08-28 14:14 ` Will Deacon
2019-08-28 21:03 ` Kees Cook
2019-08-31 17:48 ` Ard Biesheuvel
2019-08-31 19:02 ` Kees Cook
2019-08-31 20:54 ` Ard Biesheuvel
2019-09-06 13:43 ` Will Deacon
2019-09-07 1:57 ` Hanjun Guo
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