Date: Wed, 4 Apr 2018 11:31:41 -0700 From: Laura Abbott <labbott@...hat.com> To: Andy Shevchenko <andy.shevchenko@...il.com> Cc: Linus Walleij <linus.walleij@...aro.org>, Kees Cook <keescook@...omium.org>, Lukas Wunner <lukas@...ner.de>, "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, kernel-hardening@...ts.openwall.com, Rasmus Villemoes <linux@...musvillemoes.dk> Subject: Re: [PATCHv3] gpio: Remove VLA from gpiolib On 03/30/2018 07:33 AM, Andy Shevchenko wrote: > On Wed, Mar 28, 2018 at 9:18 PM, Laura Abbott <labbott@...hat.com> wrote: >> The new challenge is to remove VLAs from the kernel >> (see https://lkml.org/lkml/2018/3/7/621) to eventually >> turn on -Wvla. >> >> Using a kmalloc array is the easy way to fix this but kmalloc is still >> more expensive than stack allocation. Introduce a fast path with a >> fixed size stack array to cover most chip with gpios below some fixed >> amount. The slow path dynamically allocates an array to cover those >> chips with a large number of gpios. > >> + ret = gpiod_set_array_value_complex(false, >> true, >> lh->numdescs, >> lh->descs, >> vals); >> + if (ret) >> + return ret; >> + >> return 0; > > Can't we > > return gpiod_set_array_value_complex(); ? > > Yeah I'll clean that up for v4. >> + slowpath = kcalloc(2 * BITS_TO_LONGS(chip->ngpio), >> + sizeof(*slowpath), >> + can_sleep ? GFP_KERNEL : GFP_ATOMIC); > > >> + if (slowpath) >> + kfree(slowpath); > >> + if (slowpath) >> + kfree(slowpath); > > Since slowpath is a pointer, conditionals above are redundant. > >> + slowpath = kcalloc(2 * BITS_TO_LONGS(chip->ngpio), >> + sizeof(*slowpath), >> + can_sleep ? GFP_KERNEL : GFP_ATOMIC); > >> + if (slowpath) >> + kfree(slowpath); > > Ditto. > This was caught by a coccinelle script via 0-day but I think the request was to not do it. I'll add a comment explaining why we are going against style. Thanks, Laura
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