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From: Lukas Wunner <lukas@wunner.de>
To: Laura Abbott <labbott@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Linus Walleij <linus.walleij@linaro.org>,
	Kees Cook <keescook@chromium.org>,
	linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-hardening@lists.openwall.com,
	Mathias Duckeck <m.duckeck@kunbus.de>,
	Nandor Han <nandor.han@ge.com>,
	Semi Malinen <semi.malinen@ge.com>,
	Patrice Chotard <patrice.chotard@st.com>
Subject: Re: [PATCH 1/4] gpio: Remove VLA from gpiolib
Date: Wed, 28 Mar 2018 05:54:55 +0200	[thread overview]
Message-ID: <20180328035455.GA18149@wunner.de> (raw)
In-Reply-To: <b162140d-5c71-196b-8f1f-555fd07810df@redhat.com>

On Tue, Mar 27, 2018 at 05:37:18PM -0700, Laura Abbott wrote:
> On 03/18/2018 07:23 AM, Lukas Wunner wrote:
> > Actually, scratch that.  If ngpio is usually smallish, we can just
> > allocate reasonably sized space for mask and bits on the stack,
> > and fall back to the kcalloc slowpath only if chip->ngpio exceeds
> > that limit.  Basically the below (likewise compile-tested only),
> > this is on top of Laura's patch, could be squashed together.
> > Let me know what you think, thanks.
> >
> 
> It seems like there's general consensus this is okay so I'm going
> to fold it into the next version. If not, we can discuss again.

Yes, feel free to squash into your original patch with my S-o-b,
keep your authorship.

You may want to raise FASTPATH_NGPIO to something like 384, 448 or 512
to accommodate for the Intel chips Andy mentioned.  It's kind of a
"640k should be enough for everyone" thing but I'd expect the performance
impact of the extra bytes on the stack / memsetting them to zero
to be absolutely negligible.

Thanks!

Lukas

  reply	other threads:[~2018-03-28  3:54 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-10  0:10 [PATCH 0/4] VLA removal from the GPIO subsystem Laura Abbott
2018-03-10  0:10 ` [PATCH 1/4] gpio: Remove VLA from gpiolib Laura Abbott
2018-03-12 15:00   ` Rasmus Villemoes
2018-03-12 23:40     ` Laura Abbott
2018-03-13  7:23       ` Rasmus Villemoes
2018-03-17  8:25     ` Lukas Wunner
2018-03-18 14:23       ` Lukas Wunner
2018-03-18 20:34         ` Rasmus Villemoes
2018-03-19  7:00           ` Lukas Wunner
2018-03-19 15:09             ` Andy Shevchenko
2018-03-28  0:37         ` Laura Abbott
2018-03-28  3:54           ` Lukas Wunner [this message]
2018-03-10  0:10 ` [PATCH 2/4] gpio: Remove VLA from MAX3191X driver Laura Abbott
2018-03-26  9:07   ` Linus Walleij
2018-03-10  0:10 ` [PATCH 3/4] gpio: Remove VLA from xra1403 driver Laura Abbott
2018-03-12  6:06   ` EXT: " Nandor Han
2018-03-12  6:06     ` Nandor Han
2018-03-26  9:09   ` Linus Walleij
2018-03-28  7:27   ` Geert Uytterhoeven
2018-03-28 17:27     ` Laura Abbott
2018-04-04 12:53       ` Linus Walleij
2018-03-10  0:10 ` [PATCH 4/4] gpio: Remove VLA from stmpe driver Laura Abbott
2018-03-13  9:13   ` Phil Reid
2018-03-14  0:18     ` Laura Abbott
2018-03-14  1:16       ` Laura Abbott
2018-03-14  2:55         ` Phil Reid
2018-03-13  9:42 ` [PATCH 0/4] VLA removal from the GPIO subsystem Linus Walleij

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