Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762245AbZD3JqT (ORCPT ); Thu, 30 Apr 2009 05:46:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755365AbZD3JqG (ORCPT ); Thu, 30 Apr 2009 05:46:06 -0400 Received: from hera.kernel.org ([140.211.167.34]:56494 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750985AbZD3JqE (ORCPT ); Thu, 30 Apr 2009 05:46:04 -0400 Date: Thu, 30 Apr 2009 09:45:30 GMT From: tip-bot for Darren Hart To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, dvhltc@us.ibm.com, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de Reply-To: mingo@redhat.com, hpa@zytor.com, dvhltc@us.ibm.com, linux-kernel@vger.kernel.org, tglx@linutronix.de In-Reply-To: <49ED580E.1050502@us.ibm.com> References: <49ED580E.1050502@us.ibm.com> Subject: [tip:core/futexes] futex: remove FUTEX_REQUEUE_PI (non CMP) Message-ID: Git-Commit-ID: ba9c22f2c01cf5c88beed5a6b9e07d42e10bd358 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Thu, 30 Apr 2009 09:45:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3676 Lines: 90 Commit-ID: ba9c22f2c01cf5c88beed5a6b9e07d42e10bd358 Gitweb: http://git.kernel.org/tip/ba9c22f2c01cf5c88beed5a6b9e07d42e10bd358 Author: Darren Hart AuthorDate: Mon, 20 Apr 2009 22:22:22 -0700 Committer: Thomas Gleixner CommitDate: Thu, 30 Apr 2009 11:41:35 +0200 futex: remove FUTEX_REQUEUE_PI (non CMP) The new requeue PI futex op codes were modeled after the existing FUTEX_REQUEUE and FUTEX_CMP_REQUEUE calls. I was unaware at the time that FUTEX_REQUEUE was only around for compatibility reasons and shouldn't be used in new code. Ulrich Drepper elaborates on this in his Futexes are Tricky paper: http://people.redhat.com/drepper/futex.pdf. The deprecated call doesn't catch changes to the futex corresponding to the destination futex which can lead to deadlock. Therefor, I feel it best to remove FUTEX_REQUEUE_PI and leave only FUTEX_CMP_REQUEUE_PI as there are not yet any existing users of the API. This patch does change the OP code value of FUTEX_CMP_REQUEUE_PI to 12 from 13. Since my test case is the only known user of this API, I felt this was the right thing to do, rather than leave a hole in the enumeration. I chose to continue using the _CMP_ modifier in the OP code to make it explicit to the user that the test is being done. Builds, boots, and ran several hundred iterations requeue_pi.c. Signed-off-by: Darren Hart LKML-Reference: <49ED580E.1050502@us.ibm.com> Signed-off-by: Thomas Gleixner --- include/linux/futex.h | 4 +--- kernel/futex.c | 6 +----- 2 files changed, 2 insertions(+), 8 deletions(-) diff --git a/include/linux/futex.h b/include/linux/futex.h index b05519c..34956c8 100644 --- a/include/linux/futex.h +++ b/include/linux/futex.h @@ -24,8 +24,7 @@ union ktime; #define FUTEX_WAIT_BITSET 9 #define FUTEX_WAKE_BITSET 10 #define FUTEX_WAIT_REQUEUE_PI 11 -#define FUTEX_REQUEUE_PI 12 -#define FUTEX_CMP_REQUEUE_PI 13 +#define FUTEX_CMP_REQUEUE_PI 12 #define FUTEX_PRIVATE_FLAG 128 #define FUTEX_CLOCK_REALTIME 256 @@ -43,7 +42,6 @@ union ktime; #define FUTEX_WAKE_BITSET_PRIVATE (FUTEX_WAKE_BITS | FUTEX_PRIVATE_FLAG) #define FUTEX_WAIT_REQUEUE_PI_PRIVATE (FUTEX_WAIT_REQUEUE_PI | \ FUTEX_PRIVATE_FLAG) -#define FUTEX_REQUEUE_PI_PRIVATE (FUTEX_REQUEUE_PI | FUTEX_PRIVATE_FLAG) #define FUTEX_CMP_REQUEUE_PI_PRIVATE (FUTEX_CMP_REQUEUE_PI | \ FUTEX_PRIVATE_FLAG) diff --git a/kernel/futex.c b/kernel/futex.c index 6d2daa4..aec8bf8 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2555,9 +2555,6 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, ret = futex_wait_requeue_pi(uaddr, fshared, val, timeout, val3, clockrt, uaddr2); break; - case FUTEX_REQUEUE_PI: - ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, NULL, 1); - break; case FUTEX_CMP_REQUEUE_PI: ret = futex_requeue(uaddr, fshared, uaddr2, val, val2, &val3, 1); @@ -2596,8 +2593,7 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val, * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP. */ if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE || - cmd == FUTEX_REQUEUE_PI || cmd == FUTEX_CMP_REQUEUE_PI || - cmd == FUTEX_WAKE_OP) + cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP) val2 = (u32) (unsigned long) utime; return do_futex(uaddr, op, val, tp, uaddr2, val2, val3); -- 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/