Linux-api Archive on lore.kernel.org
 help / color / Atom feed
From: Vlastimil Babka <vbabka@suse.cz>
To: Luis Chamberlain <mcgrof@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Iurii Zaikin <yzaikin@google.com>
Cc: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	linux-mm@kvack.org, Ivan Teterevkov <ivan.teterevkov@nutanix.com>,
	Michal Hocko <mhocko@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Matthew Wilcox <willy@infradead.org>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	"Guilherme G . Piccoli" <gpiccoli@canonical.com>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: [RFC v2 2/2] kernel/sysctl: support handling command line aliases
Date: Wed, 25 Mar 2020 13:03:45 +0100
Message-ID: <20200325120345.12946-2-vbabka@suse.cz> (raw)
In-Reply-To: <20200325120345.12946-1-vbabka@suse.cz>

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 <vbabka@suse.cz>
---
 kernel/sysctl.c | 39 +++++++++++++++++++++++++++++++++++----
 mm/page_alloc.c |  9 ---------
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 18c7f5606d55..fd72853396f9 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1971,6 +1971,22 @@ static struct ctl_table dev_table[] = {
 	{ }
 };
 
+struct sysctl_alias {
+	char *kernel_param;
+	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.
+ */
+static struct sysctl_alias sysctl_aliases[] = {
+	{"numa_zonelist_order",		"vm.numa_zonelist_order" },
+	{ }
+};
+
 int __init sysctl_init(void)
 {
 	struct ctl_table_header *hdr;
@@ -1980,6 +1996,18 @@ int __init sysctl_init(void)
 	return 0;
 }
 
+char *sysctl_find_alias(char *param)
+{
+	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. */
 int process_sysctl_arg(char *param, char *val,
 			       const char *unused, void *arg)
@@ -1990,10 +2018,13 @@ int process_sysctl_arg(char *param, char *val,
 	loff_t ppos = 0;
 	struct ctl_table *ctl, *found = NULL;
 
-	if (strncmp(param, "sysctl.", sizeof("sysctl.") - 1))
-		return 0;
-
-	param += sizeof("sysctl.") - 1;
+	if (strncmp(param, "sysctl.", sizeof("sysctl.") - 1) == 0) {
+		param += sizeof("sysctl.") - 1;
+	} else {
+		param = sysctl_find_alias(param);
+		if (!param)
+			return 0;
+	}
 
 	remaining = param;
 	ctl = &sysctl_base_table[0];
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3c4eb750a199..de7a134b1b8a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5460,15 +5460,6 @@ static int __parse_numa_zonelist_order(char *s)
 	return 0;
 }
 
-static __init int setup_numa_zonelist_order(char *s)
-{
-	if (!s)
-		return 0;
-
-	return __parse_numa_zonelist_order(s);
-}
-early_param("numa_zonelist_order", setup_numa_zonelist_order);
-
 char numa_zonelist_order[] = "Node";
 
 /*
-- 
2.25.1


  reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25 12:03 [RFC v2 1/2] kernel/sysctl: support setting sysctl parameters from kernel command line Vlastimil Babka
2020-03-25 12:03 ` Vlastimil Babka [this message]
2020-03-25 14:29   ` [RFC v2 2/2] kernel/sysctl: support handling command line aliases Michal Hocko
2020-03-25 14:36     ` Vlastimil Babka
2020-03-25 14:44       ` Michal Hocko
2020-03-25 22:42   ` Kees Cook
2020-03-29 15:00   ` Arvind Sankar
2020-03-25 21:21 ` [RFC v2 1/2] kernel/sysctl: support setting sysctl parameters from kernel command line Kees Cook
2020-03-26  9:30   ` Vlastimil Babka
2020-03-25 22:20 ` Eric W. Biederman
2020-03-25 22:54   ` Kees Cook
2020-03-26  6:58   ` Michal Hocko
2020-03-26  7:21     ` Kees Cook
2020-03-26 12:45     ` Eric W. Biederman
2020-03-30 22:09       ` Luis Chamberlain
2020-03-26 13:30     ` Christian Brauner
2020-03-26 13:39       ` Michal Hocko
2020-03-26 13:29   ` Vlastimil Babka

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200325120345.12946-2-vbabka@suse.cz \
    --to=vbabka@suse.cz \
    --cc=ebiederm@xmission.com \
    --cc=gpiccoli@canonical.com \
    --cc=ivan.teterevkov@nutanix.com \
    --cc=keescook@chromium.org \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mcgrof@kernel.org \
    --cc=mhocko@kernel.org \
    --cc=rientjes@google.com \
    --cc=willy@infradead.org \
    --cc=yzaikin@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-api Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-api/0 linux-api/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-api linux-api/ https://lore.kernel.org/linux-api \
		linux-api@vger.kernel.org
	public-inbox-index linux-api

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-api


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git