From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4B0E4CA5FB1 for ; Tue, 29 Sep 2026 16:59:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=MGBWHHaEJganj8D1yagMHRlcdsNEyTtM3iC7GV8hUXU=; b=ANSPZoEhKvRFTfhVGrcGKo35Ms RFjbQJLUQEMHMMJoPEDCjCvaVYG59gW4mslp+zGVwgOtBfhvNrmKX7K/jFzJApPJMW0Vx5qDvS9m9 MOWzLKBKujNuVRloCc4eHKTduqsil4rH9JNzV2rC3EF8Xl/nUY/2zWly/QWjixEZWdMT9/gBNajbR SoRoJkthzqdzWBAnQxcMBMS+J6yGzxGo8AaZksJ69jsdVGxVOSwRGRLCyUYgbatevHXm3s0eYpwG3 uo6a9LbzJ/9Zc2h3DqtgHqMjVUm59zEtdhEGzG+RikOOe7U2qZsliT6dtKbhFK+WemiyVeZF+FiQg jCx8dv0g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xBbBH-000000047QD-2izB; Tue, 29 Sep 2026 16:59:51 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xBbBH-000000047Q0-0HLi; Tue, 29 Sep 2026 16:59:51 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 6AB8243BFA; Tue, 29 Sep 2026 16:59:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 153C71F000FF; Tue, 29 Sep 2026 16:59:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790701190; bh=MGBWHHaEJganj8D1yagMHRlcdsNEyTtM3iC7GV8hUXU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=SjePm7x02Lah5vOELf9ce4YUO5z/8quB47KG1ZoIMK72aUNVrPrCdr0c0MhVEUCct e/pjkzplRRlc+iDw8myI00JnCkhOCgIGqKVjqAEmF68e1bsSBFWkNDo/dnGaHUUbmN gGTfswdR99FIW24ZhkxFSWQUM+NnT0oWNEgj5t/DAU3kIqebd4giVteYXHP1sJE9R7 LMnUflkro8TfjhlCllhq8FQKM35R/YNnamS2pvqYaCoDITHJ1zkhAY1dQR0e4Sb4q1 loj77pP8vyLLK7xfd/8pczOKmPjnIREFvATiAc8+2ruPOGvW7PPEKs8kujnvVWWvGM j5+6rTn2iVdcw== Date: Tue, 29 Sep 2026 18:59:39 +0200 From: Nathan Chancellor To: David Laight Cc: "Jason A. Donenfeld" , Andreas Schwab , Andy Lutomirski , Thomas Gleixner , Theodore Ts'o , Vincenzo Frascino , Nick Desaulniers , Bill Wendling , Justin Stitt , Catalin Marinas , Will Deacon , Mark Rutland , Huacai Chen , WANG Xuerui , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v2] random: vDSO: Avoid call to memset() when zeroing reserved in __cvdso_getrandom_data() Message-ID: <20260929165939.GA1890629@ax162> References: <20260925-vdso-getrandom-avoid-memset-llvm-24-v2-1-ce640f872393@kernel.org> <87zex4ic68.fsf@linux-m68k.org> <20260926121927.GA1486962@ax162> <20260927080225.37534e7c@pumpkin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260927080225.37534e7c@pumpkin> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Sep 27, 2026 at 08:02:25AM +0100, David Laight wrote: > On Sat, 26 Sep 2026 14:32:49 +0200 > "Jason A. Donenfeld" wrote: > > Do we even need to return a value at all? Might as well just make the > > function two lines: > > > > + for (char *d = dst; size--;) > > + *d++ = value; > > Wouldn't it be better to add a barrier() or similar in there to > stop the compiler playing unwanted games> Wouldn't that just result in the same code generation issue that Jason pointed out on my v1? https://lore.kernel.org/aquyVkdYceiWdckX@zx2c4.com/ Maybe that doesn't matter because modern compilers have better options? -- Cheers, Nathan