linux-kernel - [tip: sched/urgent] sched/membarrier: Remove redundant check

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <156957184378.9866.15796834930588841787.tip-bot2@tip-bot2>
Date:   Fri, 27 Sep 2019 08:10:43 -0000
From:   "tip-bot2 for Mathieu Desnoyers" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Oleg Nesterov <oleg@...hat.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Chris Metcalf <cmetcalf@...hip.com>,
        Christoph Lameter <cl@...ux.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Kirill Tkhai <tkhai@...dex.ru>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Galbraith <efault@....de>,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>,
        "Russell King - ARM Linux admin" <linux@...linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/urgent] sched/membarrier: Remove redundant check

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     09554009c0cad4cb2223dd943c813c9257c6883a
Gitweb:        https://git.kernel.org/tip/09554009c0cad4cb2223dd943c813c9257c6883a
Author:        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
AuthorDate:    Thu, 19 Sep 2019 13:37:00 -04:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 25 Sep 2019 17:42:30 +02:00

sched/membarrier: Remove redundant check

Checking that the number of threads is 1 is redundant with checking
mm_users == 1.

No change in functionality intended.

Suggested-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Chris Metcalf <cmetcalf@...hip.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: Kirill Tkhai <tkhai@...dex.ru>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Paul E. McKenney <paulmck@...ux.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-3-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/membarrier.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index d48b95f..7ccbd0e 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -186,7 +186,7 @@ static int membarrier_register_global_expedited(void)
 	    MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY)
 		return 0;
 	atomic_or(MEMBARRIER_STATE_GLOBAL_EXPEDITED, &mm->membarrier_state);
-	if (atomic_read(&mm->mm_users) == 1 && get_nr_threads(p) == 1) {
+	if (atomic_read(&mm->mm_users) == 1) {
 		/*
 		 * For single mm user, single threaded process, we can
 		 * simply issue a memory barrier after setting
@@ -232,7 +232,7 @@ static int membarrier_register_private_expedited(int flags)
 	if (flags & MEMBARRIER_FLAG_SYNC_CORE)
 		atomic_or(MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE,
 			  &mm->membarrier_state);
-	if (!(atomic_read(&mm->mm_users) == 1 && get_nr_threads(p) == 1)) {
+	if (atomic_read(&mm->mm_users) != 1) {
 		/*
 		 * Ensure all future scheduler executions will observe the
 		 * new thread flag state for this process.