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 X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, WEIRD_QUOTING autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08A9AC2D0ED for ; Thu, 26 Mar 2020 21:29:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BCCB720658 for ; Thu, 26 Mar 2020 21:29:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BCCB720658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ubuntu.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6A25F6B0008; Thu, 26 Mar 2020 17:29:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 629BF6B000A; Thu, 26 Mar 2020 17:29:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 518B06B000C; Thu, 26 Mar 2020 17:29:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0245.hostedemail.com [216.40.44.245]) by kanga.kvack.org (Postfix) with ESMTP id 362C06B0008 for ; Thu, 26 Mar 2020 17:29:16 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 01722181AD0A6 for ; Thu, 26 Mar 2020 21:29:16 +0000 (UTC) X-FDA: 76638804270.02.crow23_16a7240f2a620 X-HE-Tag: crow23_16a7240f2a620 X-Filterd-Recvd-Size: 4659 Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Thu, 26 Mar 2020 21:29:15 +0000 (UTC) Received: from ip5f5bf7ec.dynamic.kabel-deutschland.de ([95.91.247.236] helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1jHa3m-0005bi-TH; Thu, 26 Mar 2020 21:29:07 +0000 Date: Thu, 26 Mar 2020 22:29:06 +0100 From: Christian Brauner To: Kees Cook Cc: Vlastimil Babka , Luis Chamberlain , Iurii Zaikin , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, linux-mm@kvack.org, Ivan Teterevkov , Michal Hocko , David Rientjes , Matthew Wilcox , "Eric W . Biederman" , "Guilherme G . Piccoli" Subject: Re: [RFC v3 2/2] kernel/sysctl: support handling command line aliases Message-ID: <20200326212906.muutd636zfoytcgh@wittgenstein> References: <20200326181606.7027-1-vbabka@suse.cz> <20200326181606.7027-2-vbabka@suse.cz> <202003261329.AAFEE9C@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <202003261329.AAFEE9C@keescook> 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: On Thu, Mar 26, 2020 at 01:34:08PM -0700, Kees Cook wrote: > On Thu, Mar 26, 2020 at 07:16:06PM +0100, Vlastimil Babka wrote: > > We can now handle sysctl parameters on kernel command line, but historically > > some parameters introduced their own command line equivalent, which we don't > > want to remove for compatibility reasons. We can however convert them to the > > generic infrastructure with a table translating the legacy command line > > parameters to their sysctl names, and removing the one-off param handlers. > > > > This patch adds the support and makes the first conversion to demonstrate it, > > on the (deprecated) numa_zonelist_order parameter. > > > > Signed-off-by: Vlastimil Babka > > --- > > Changes in v3: > > - constify some things according to Kees > > - expand the comment of sysctl_aliases to note on different timings > > > > fs/proc/proc_sysctl.c | 48 ++++++++++++++++++++++++++++++++++++------- > > mm/page_alloc.c | 9 -------- > > 2 files changed, 41 insertions(+), 16 deletions(-) > > > > diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c > > index 8ee3273e4540..3a861e0a7c7e 100644 > > --- a/fs/proc/proc_sysctl.c > > +++ b/fs/proc/proc_sysctl.c > > @@ -1729,6 +1729,37 @@ int __init proc_sys_init(void) > > > > struct vfsmount *proc_mnt = NULL; > > > > +struct sysctl_alias { > > + const char *kernel_param; > > + const char *sysctl_param; > > +}; > > + > > +/* > > + * Historically some settings had both sysctl and a command line parameter. > > + * With the generic sysctl. parameter support, we can handle them at a single > > + * place and only keep the historical name for compatibility. This is not meant > > + * to add brand new aliases. When adding existing aliases, consider whether > > + * the possibly different moment of changing the value (e.g. from early_param > > + * to the moment do_sysctl_args() is called) is an issue for the specific > > + * parameter. > > + */ > > +static const struct sysctl_alias sysctl_aliases[] = { > > + {"numa_zonelist_order", "vm.numa_zonelist_order" }, > > + { } > > +}; > > + > > +const char *sysctl_find_alias(char *param) > > This should be "static" too. > > > +{ > > + const struct sysctl_alias *alias; > > + > > + for (alias = &sysctl_aliases[0]; alias->kernel_param != NULL; alias++) { > > + if (strcmp(alias->kernel_param, param) == 0) > > + return alias->sysctl_param; > > + } > > + > > + return NULL; > > +} > > + > > /* Set sysctl value passed on kernel command line. */ > > static int process_sysctl_arg(char *param, char *val, > > const char *unused, void *arg) > > @@ -1741,15 +1772,18 @@ static int process_sysctl_arg(char *param, char *val, > > loff_t pos = 0; > > ssize_t wret; > > > > - if (strncmp(param, "sysctl", sizeof("sysctl") - 1)) Somewhat off-topic but in some projects I use macro-helpers to make that more transparent. So this would become a constant expression: #define STRLITERALLEN(x) (sizeof(""x"") - 1) or #define STRLEN(x) (sizeof(""x"") - 1) But I guess that's a matter of style/taste. Christian