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] [4/9] SYSCTL: Use RCU strings for core_pattern sysctl
Date: Tue, 5 Jan 2010 03:15:29 +0100 (CET) [thread overview]
Message-ID: <20100105021529.205EFB17C2@basil.firstfloor.org> (raw)
In-Reply-To: <20100105315.789846878@firstfloor.org>
Also saves ~220 bytes in the data segment for default kernels.
As a bonus this removes one use of the BKL.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
fs/exec.c | 11 +++++------
kernel/sysctl.c | 6 +++---
2 files changed, 8 insertions(+), 9 deletions(-)
Index: linux-2.6.33-rc2-ak/fs/exec.c
===================================================================
--- linux-2.6.33-rc2-ak.orig/fs/exec.c
+++ linux-2.6.33-rc2-ak/fs/exec.c
@@ -62,7 +62,7 @@
#include "internal.h"
int core_uses_pid;
-char core_pattern[CORENAME_MAX_SIZE] = "core";
+char *core_pattern = "core";
unsigned int core_pipe_limit;
int suid_dumpable = 0;
@@ -1421,7 +1421,7 @@ EXPORT_SYMBOL(set_binfmt);
static int format_corename(char *corename, long signr)
{
const struct cred *cred = current_cred();
- const char *pat_ptr = core_pattern;
+ const char *pat_ptr = rcu_dereference(core_pattern);
int ispipe = (*pat_ptr == '|');
char *out_ptr = corename;
char *const out_end = corename + CORENAME_MAX_SIZE;
@@ -1825,12 +1825,11 @@ void do_coredump(long signr, int exit_co
clear_thread_flag(TIF_SIGPENDING);
/*
- * lock_kernel() because format_corename() is controlled by sysctl, which
- * uses lock_kernel()
+ * Protect corename by RCU vs proc_rcu_string()
*/
- lock_kernel();
+ rcu_read_lock();
ispipe = format_corename(corename, signr);
- unlock_kernel();
+ rcu_read_unlock();
if ((!ispipe) && (cprm.limit < binfmt->min_coredump))
goto fail_unlock;
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
@@ -75,7 +75,7 @@ extern int sysctl_oom_dump_tasks;
extern int max_threads;
extern int core_uses_pid;
extern int suid_dumpable;
-extern char core_pattern[];
+extern char *core_pattern;
extern unsigned int core_pipe_limit;
extern int pid_max;
extern int min_free_kbytes;
@@ -399,10 +399,10 @@ static struct ctl_table kern_table[] = {
},
{
.procname = "core_pattern",
- .data = core_pattern,
+ .data = &core_pattern,
.maxlen = CORENAME_MAX_SIZE,
.mode = 0644,
- .proc_handler = proc_dostring,
+ .proc_handler = proc_rcu_string,
},
{
.procname = "core_pipe_limit",
next prev parent reply other threads:[~2010-01-05 2:15 UTC|newest]
Thread overview: 24+ 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
2010-01-08 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 ` Andi Kleen [this message]
2010-01-05 6:56 ` [PATCH] [4/9] SYSCTL: Use RCU strings for core_pattern sysctl 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 ` [PATCH] [7/9] SYSCTL: Convert poweroff_command to proc_rcu_string Andi Kleen
2010-01-05 2:15 ` [PATCH] [8/9] SYSCTL: Convert hotplug helper string to proc_rcu_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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