From: Andi Kleen <andi@firstfloor.org>
To: ebiederm@xmission.com, paulmck@linux.vnet.ibm.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: [PATCH] [7/9] SYSCTL: Convert poweroff_command to proc_rcu_string
Date: Tue, 5 Jan 2010 03:15:32 +0100 (CET) [thread overview]
Message-ID: <20100105021532.3BE00B17C2@basil.firstfloor.org> (raw)
In-Reply-To: <20100105315.789846878@firstfloor.org>
Avoids races with lockless sysctl.
Also saves ~220 bytes in the data segment for default kernels.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
include/linux/reboot.h | 2 +-
kernel/sys.c | 8 ++++++--
kernel/sysctl.c | 2 +-
3 files changed, 8 insertions(+), 4 deletions(-)
Index: linux-2.6.33-rc2-ak/kernel/sys.c
===================================================================
--- linux-2.6.33-rc2-ak.orig/kernel/sys.c
+++ linux-2.6.33-rc2-ak/kernel/sys.c
@@ -1597,7 +1597,7 @@ SYSCALL_DEFINE3(getcpu, unsigned __user
return err ? -EFAULT : 0;
}
-char poweroff_cmd[POWEROFF_CMD_PATH_LEN] = "/sbin/poweroff";
+char *poweroff_cmd = "/sbin/poweroff";
static void argv_cleanup(char **argv, char **envp)
{
@@ -1614,7 +1614,7 @@ static void argv_cleanup(char **argv, ch
int orderly_poweroff(bool force)
{
int argc;
- char **argv = argv_split(GFP_ATOMIC, poweroff_cmd, &argc);
+ char **argv;
static char *envp[] = {
"HOME=/",
"PATH=/sbin:/bin:/usr/sbin:/usr/bin",
@@ -1623,6 +1623,10 @@ int orderly_poweroff(bool force)
int ret = -ENOMEM;
struct subprocess_info *info;
+ /* RCU protection for poweroff_cmd */
+ rcu_read_lock();
+ argv = argv_split(GFP_ATOMIC, rcu_dereference(poweroff_cmd), &argc);
+ rcu_read_unlock();
if (argv == NULL) {
printk(KERN_WARNING "%s failed to allocate memory for \"%s\"\n",
__func__, poweroff_cmd);
Index: linux-2.6.33-rc2-ak/include/linux/reboot.h
===================================================================
--- linux-2.6.33-rc2-ak.orig/include/linux/reboot.h
+++ linux-2.6.33-rc2-ak/include/linux/reboot.h
@@ -67,7 +67,7 @@ extern void kernel_power_off(void);
void ctrl_alt_del(void);
#define POWEROFF_CMD_PATH_LEN 256
-extern char poweroff_cmd[POWEROFF_CMD_PATH_LEN];
+extern char *poweroff_cmd;
extern int orderly_poweroff(bool force);
Index: linux-2.6.33-rc2-ak/kernel/sysctl.c
===================================================================
--- linux-2.6.33-rc2-ak.orig/kernel/sysctl.c
+++ linux-2.6.33-rc2-ak/kernel/sysctl.c
@@ -871,7 +871,7 @@ static struct ctl_table kern_table[] = {
.data = &poweroff_cmd,
.maxlen = POWEROFF_CMD_PATH_LEN,
.mode = 0644,
- .proc_handler = proc_dostring,
+ .proc_handler = proc_rcu_string,
},
#ifdef CONFIG_KEYS
{
next prev parent reply other threads:[~2010-01-05 2:15 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-05 2:15 [PATCH] [0/9] SYSCTL: Use RCU to avoid races with string sysctls v2 Andi Kleen
2010-01-05 2:15 ` [PATCH] [1/9] Add rcustring ADT for RCU protected strings v2 Andi Kleen
2010-01-05 5:32 ` Paul E. McKenney
2010-01-05 10:47 ` Andi Kleen
2010-01-05 14:11 ` Paul E. McKenney
2010-01-05 14:19 ` Andi Kleen
2010-01-08 23:50 ` Andrew Morton
2010-01-11 12:12 ` Bert Wesarg
2010-01-11 14:26 ` Andi Kleen
2010-01-05 2:15 ` [PATCH] [2/9] Add a kernel_address() that works for data too Andi Kleen
2010-01-05 8:44 ` Russell King
2010-01-05 8:58 ` Sam Ravnborg
2010-01-05 19:04 ` Russell King
2010-01-05 19:15 ` Andi Kleen
2010-01-05 19:15 ` Andi Kleen
2010-01-08 23:51 ` Andrew Morton
2010-01-05 2:15 ` [PATCH] [3/9] SYSCTL: Add proc_rcu_string to manage sysctls using rcu strings Andi Kleen
2010-01-05 2:15 ` [PATCH] [4/9] SYSCTL: Use RCU strings for core_pattern sysctl Andi Kleen
2010-01-05 6:56 ` Eric W. Biederman
2010-01-05 11:49 ` Andi Kleen
2010-01-05 2:15 ` [PATCH] [5/9] SYSCTL: Add call_usermodehelper_cleanup() Andi Kleen
2010-01-05 2:15 ` [PATCH] [6/9] SYSCTL: Convert modprobe_path to proc_rcu_string() Andi Kleen
2010-01-05 2:15 ` Andi Kleen [this message]
2010-01-05 2:15 ` [PATCH] [8/9] SYSCTL: Convert hotplug helper string " Andi Kleen
2010-01-05 2:15 ` [PATCH] [9/9] SYSCTL: Use RCU protected sysctl for ocfs group add helper Andi Kleen
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