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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE976CA0ED1 for ; Mon, 18 Aug 2025 08:12:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 40BD46B00BD; Mon, 18 Aug 2025 04:12:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3957D6B00C0; Mon, 18 Aug 2025 04:12:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2354F6B00BE; Mon, 18 Aug 2025 04:12:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 0B2BC6B00BA for ; Mon, 18 Aug 2025 04:12:33 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 8E3BB139069 for ; Mon, 18 Aug 2025 08:12:32 +0000 (UTC) X-FDA: 83789161344.24.A486C07 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf07.hostedemail.com (Postfix) with ESMTP id E52E140007 for ; Mon, 18 Aug 2025 08:12:30 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf07.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1755504751; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CN6XG4uuIHF4W8Irdw+nTi/wMcYkYvFzKNumSMVxm4U=; b=O2vVmHMy/83QTR/Fa7ILvLIj45HYxm8yAhixGMz+HFPpdXbayYGSzHsVwEJAiXernqx43R rlv4ZBqK7qtlTXdwN8H6e3OdtYUy/SsbzPSb8wAFMVjZU4+iyHYtuYLPzaG7jeYNeXGc2K VwjUemW2Im1VoBL4lWQdmO72UTZyUA0= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1755504751; a=rsa-sha256; cv=none; b=a3IEuHzjsIvEhKcKBWlV5uLNsUdwOwFk9sWmtJ1qPdv5XlrpDSa+SuoKfa5idL/qNDu84E MMXRS3IbpsI4hUwpo/ZsPETrTMZ+nrYVw9a1Zk50DrvoD9qUNujdon4TOem2O4kXEz0JFw ghBnTDqH/mUA5Zmi1CB0sDg25vO/ZZU= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf07.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 028561762; Mon, 18 Aug 2025 01:12:22 -0700 (PDT) Received: from [10.57.58.12] (unknown [10.57.58.12]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A60AF3F63F; Mon, 18 Aug 2025 01:12:24 -0700 (PDT) Message-ID: <28d7d186-5068-4546-90af-f9a9a0147f21@arm.com> Date: Mon, 18 Aug 2025 10:12:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/8] selftests/mm: protection_keys: Fix dead code To: Muhammad Usama Anjum , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jason Gunthorpe , John Hubbard , Peter Xu , Leon Romanovsky , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, Shuah Khan , Dave Hansen Cc: kernel@collabora.com References: <20250731160132.1795351-1-usama.anjum@collabora.com> <20250731160132.1795351-3-usama.anjum@collabora.com> Content-Language: en-GB From: Kevin Brodsky In-Reply-To: <20250731160132.1795351-3-usama.anjum@collabora.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: E52E140007 X-Stat-Signature: t7g1jgjce4exjm7iys8yksz4btgixq4a X-Rspam-User: X-HE-Tag: 1755504750-139410 X-HE-Meta: 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 0caEuMBZ YwfvbLBADW8Kq68lvEZ9pOKRhyvs+1Jv8b3ip70rdNPlsbqJMjXeTGhvGBci4vr/zLLDpqF4cdIT/FtQtPG9o7CEpPo6TMtkkNqWMUoBh27ivqps+YR+VrMi/OIDWeNPMapjKBT2KmJNVDCgijzpAext/87abkxFfQpElsC8Oga3E0V1SIidoA+d+2r4BTBk8hkaB+H6jhvwPVpMxe6+KrjzA1O3AeXhUx4GOvRO+aCS00IbRdRRjFGA2fc7dSC7FHgXomSyZFt9HdxdqwUoau6jX51OZyxI+YzB3XAOmrfd87lI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: +Dave Hansen On 31/07/2025 18:01, Muhammad Usama Anjum wrote: > The while loop doesn't execute and following warning gets generated: > > protection_keys.c:561:15: warning: code will never be executed > [-Wunreachable-code] > int rpkey = alloc_random_pkey(); > > Let's enable the while loop such that it gets executed nr_iterations > times. Simplify the code a bit as well. > > Signed-off-by: Muhammad Usama Anjum > --- > tools/testing/selftests/mm/protection_keys.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c > index 23ebec367015f..6281d4c61b50e 100644 > --- a/tools/testing/selftests/mm/protection_keys.c > +++ b/tools/testing/selftests/mm/protection_keys.c > @@ -557,13 +557,11 @@ int mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot, > int nr_iterations = random() % 100; > int ret; > > - while (0) { > + while (nr_iterations-- >= 0) { Now that is a good catch! I had never realised this whole loop was dead code... The question is whether we really want it. This code looked exactly this way when it was merged [1] so it has never been run. It looks suspiciously like debug code. Dave, should we just remove this? - Kevin [1] https://lore.kernel.org/all/20160729163024.FC5A0C2D@viggo.jf.intel.com/T/#u > int rpkey = alloc_random_pkey(); > ret = sys_mprotect_pkey(ptr, size, orig_prot, pkey); > dprintf1("sys_mprotect_pkey(%p, %zx, prot=0x%lx, pkey=%ld) ret: %d\n", > ptr, size, orig_prot, pkey, ret); > - if (nr_iterations-- < 0) > - break; > > dprintf1("%s()::%d, ret: %d pkey_reg: 0x%016llx" > " shadow: 0x%016llx\n",