From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22542C4332B for ; Fri, 20 Mar 2020 17:10:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0496F20739 for ; Fri, 20 Mar 2020 17:10:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727209AbgCTRKE (ORCPT ); Fri, 20 Mar 2020 13:10:04 -0400 Received: from mx2.suse.de ([195.135.220.15]:35886 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726973AbgCTRKE (ORCPT ); Fri, 20 Mar 2020 13:10:04 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 75934B00D; Fri, 20 Mar 2020 17:10:02 +0000 (UTC) Date: Fri, 20 Mar 2020 10:09:02 -0700 From: Davidlohr Bueso To: dhowells@redhat.com Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: Re: [PATCH] security, keys: Optimize barrier usage for Rmw atomic bitops Message-ID: <20200320170902.ilwugh33co3poqm3@linux-p48b> References: <20200129180625.24486-1-dave@stgolabs.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200129180625.24486-1-dave@stgolabs.net> User-Agent: NeoMutt/20180716 Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: ping? On Wed, 29 Jan 2020, Davidlohr Bueso wrote: >For both set and clear_bit, we can avoid the unnecessary barriers >on non LL/SC architectures, such as x86. Instead, use the >smp_mb__{before,after}_atomic() calls. > >Signed-off-by: Davidlohr Bueso >--- > security/keys/gc.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > >diff --git a/security/keys/gc.c b/security/keys/gc.c >index 671dd730ecfc..ce7b4c22e3c4 100644 >--- a/security/keys/gc.c >+++ b/security/keys/gc.c >@@ -102,7 +102,7 @@ void key_gc_keytype(struct key_type *ktype) > > key_gc_dead_keytype = ktype; > set_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags); >- smp_mb(); >+ smp_mb__after_atomic(); > set_bit(KEY_GC_REAP_KEYTYPE, &key_gc_flags); > > kdebug("schedule"); >@@ -308,7 +308,7 @@ static void key_garbage_collector(struct work_struct *work) > > if (unlikely(gc_state & KEY_GC_REAPING_DEAD_3)) { > kdebug("dead wake"); >- smp_mb(); >+ smp_mb__before_atomic(); > clear_bit(KEY_GC_REAPING_KEYTYPE, &key_gc_flags); > wake_up_bit(&key_gc_flags, KEY_GC_REAPING_KEYTYPE); > } >-- >2.16.4 >