linux-kernel - RE: [PATCH] fs/select: avoid clang stack usage warning

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Message-ID: <b211e3a2549844fa957ca84b9257872d@AcuMS.aculab.com>
Date:   Sun, 9 Oct 2022 10:49:52 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Nick Desaulniers' <ndesaulniers@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Kees Cook <keescook@...omium.org>
CC:     "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "Alexander Viro" <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Christoph Hellwig <hch@....de>,
        Eric Dumazet <edumazet@...gle.com>,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>,
        Paul Kirth <paulkirth@...gle.com>
Subject: RE: [PATCH] fs/select: avoid clang stack usage warning

From: Nick Desaulniers
> Sent: 07 October 2022 20:04
...
> It looks like for arrays INIT_STACK_ALL_PATTERN uses memset to fill
> the array with 0xFF rather than 0x00 used by INIT_STACK_ALL_ZERO. Not
> sure why that would make a difference, but curious that it does.

How much performance does filling the array cost?
I'd suspect it is enough to be measurable.

	David

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