Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753846AbZK0XGN (ORCPT ); Fri, 27 Nov 2009 18:06:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753797AbZK0XGL (ORCPT ); Fri, 27 Nov 2009 18:06:11 -0500 Received: from server1.wserver.cz ([82.113.45.157]:60453 "EHLO server1.wserver.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753063AbZK0XGE (ORCPT ); Fri, 27 Nov 2009 18:06:04 -0500 From: Jiri Slaby To: jirislaby@gmail.com Cc: mingo@elte.hu, nhorman@tuxdriver.com, sfr@canb.auug.org.au, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, marcin.slusarz@gmail.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, torvalds@linux-foundation.org, oleg@redhat.com Subject: [PATCH v3 07/27] core: optimize setrlimit for current task Date: Sat, 28 Nov 2009 00:05:47 +0100 Message-Id: <1259363167-9347-7-git-send-email-jslaby@suse.cz> X-Mailer: git-send-email 1.6.5.3 In-Reply-To: <1259363167-9347-1-git-send-email-jslaby@suse.cz> References: <1259363167-9347-1-git-send-email-jslaby@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1640 Lines: 55 From: Jiri Slaby Don't take tasklist lock for 'current'. It's not needed, since current->sighand/signal can't disappear. This improves serlimit called especially via sys_setrlimit. Signed-off-by: Jiri Slaby Cc: Oleg Nesterov --- kernel/sys.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index 3082eaf..605ab9c 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1250,11 +1250,14 @@ int setrlimit(struct task_struct *tsk, unsigned int resource, if (resource == RLIMIT_NOFILE && new_rlim->rlim_max > sysctl_nr_open) return -EPERM; - /* protect tsk->signal and tsk->sighand from disappearing */ - read_lock(&tasklist_lock); - if (!tsk->sighand) { - retval = -ESRCH; - goto out; + /* optimization: 'current' doesn't need locking, e.g. setrlimit */ + if (tsk != current) { + /* protect tsk->signal and tsk->sighand from disappearing */ + read_lock(&tasklist_lock); + if (!tsk->sighand) { + retval = -ESRCH; + goto out; + } } retval = security_task_setrlimit(tsk, resource, new_rlim); @@ -1294,7 +1297,8 @@ int setrlimit(struct task_struct *tsk, unsigned int resource, update_rlimit_cpu(tsk, new_rlim->rlim_cur); out: - read_unlock(&tasklist_lock); + if (tsk != current) + read_unlock(&tasklist_lock); return retval; } -- 1.6.5.3 -- 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/