Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754498Ab0AECPg (ORCPT ); Mon, 4 Jan 2010 21:15:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754420Ab0AECPd (ORCPT ); Mon, 4 Jan 2010 21:15:33 -0500 Received: from one.firstfloor.org ([213.235.205.2]:43070 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754108Ab0AECPa (ORCPT ); Mon, 4 Jan 2010 21:15:30 -0500 From: Andi Kleen References: <20100105315.789846878@firstfloor.org> In-Reply-To: <20100105315.789846878@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 Message-Id: <20100105021529.205EFB17C2@basil.firstfloor.org> Date: Tue, 5 Jan 2010 03:15:29 +0100 (CET) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2520 Lines: 81 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 --- 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", -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/