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Message-ID: <20180328035455.GA18149@wunner.de> Date: Wed, 28 Mar 2018 05:54:55 +0200 From: Lukas Wunner <lukas@...ner.de> To: Laura Abbott <labbott@...hat.com> Cc: Rasmus Villemoes <linux@...musvillemoes.dk>, Linus Walleij <linus.walleij@...aro.org>, Kees Cook <keescook@...omium.org>, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com, Mathias Duckeck <m.duckeck@...bus.de>, Nandor Han <nandor.han@...com>, Semi Malinen <semi.malinen@...com>, Patrice Chotard <patrice.chotard@...com> Subject: Re: [PATCH 1/4] gpio: Remove VLA from gpiolib 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
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