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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT 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 0C888ECDE44 for ; Fri, 26 Oct 2018 13:49:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C94AF20869 for ; Fri, 26 Oct 2018 13:49:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C94AF20869 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727755AbeJZW0Z (ORCPT ); Fri, 26 Oct 2018 18:26:25 -0400 Received: from mx2.suse.de ([195.135.220.15]:44840 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727591AbeJZWZr (ORCPT ); Fri, 26 Oct 2018 18:25:47 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 46287B054; Fri, 26 Oct 2018 13:48:38 +0000 (UTC) From: Nicolas Saenz Julienne To: stefan.wahren@i2se.com, eric@anholt.net, dave.stevenson@raspberrypi.org Cc: nsaenzjulienne@suse.de, linux-rpi-kernel@lists.infradead.org, gregkh@linuxfoundation.org, linux-arm-kernel@lists.infradead.org, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: [PATCH RFC 14/18] staging: vchiq_util: get rid of unneeded memory barriers Date: Fri, 26 Oct 2018 15:48:09 +0200 Message-Id: <20181026134813.7775-15-nsaenzjulienne@suse.de> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181026134813.7775-1-nsaenzjulienne@suse.de> References: <20181026134813.7775-1-nsaenzjulienne@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org All the memory operations featured in this file modify/access memory that is only accessed by the CPU. So we can assume that all the memory barrier handling done by the completion routines is good enough for us. Signed-off-by: Nicolas Saenz Julienne --- .../interface/vchiq_arm/vchiq_util.c | 32 ------------------- 1 file changed, 32 deletions(-) diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c index 44b954daa74a..4b8554bc647e 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c @@ -84,20 +84,7 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) flush_signals(current); } - /* - * Write to queue->storage must be visible after read from - * queue->read - */ - smp_mb(); - queue->storage[queue->write & (queue->size - 1)] = header; - - /* - * Write to queue->storage must be visible before write to - * queue->write - */ - smp_wmb(); - queue->write++; complete(&queue->push); @@ -112,12 +99,6 @@ VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue) complete(&queue->push); // We haven't removed anything from the queue. - /* - * Read from queue->storage must be visible after read from - * queue->write - */ - smp_rmb(); - return queue->storage[queue->read & (queue->size - 1)]; } @@ -130,20 +111,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) flush_signals(current); } - /* - * Read from queue->storage must be visible after read from - * queue->write - */ - smp_rmb(); - header = queue->storage[queue->read & (queue->size - 1)]; - - /* - * Read from queue->storage must be visible before write to - * queue->read - */ - smp_mb(); - queue->read++; complete(&queue->pop); -- 2.19.1 From mboxrd@z Thu Jan 1 00:00:00 1970 From: nsaenzjulienne@suse.de (Nicolas Saenz Julienne) Date: Fri, 26 Oct 2018 15:48:09 +0200 Subject: [PATCH RFC 14/18] staging: vchiq_util: get rid of unneeded memory barriers In-Reply-To: <20181026134813.7775-1-nsaenzjulienne@suse.de> References: <20181026134813.7775-1-nsaenzjulienne@suse.de> Message-ID: <20181026134813.7775-15-nsaenzjulienne@suse.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org All the memory operations featured in this file modify/access memory that is only accessed by the CPU. So we can assume that all the memory barrier handling done by the completion routines is good enough for us. Signed-off-by: Nicolas Saenz Julienne --- .../interface/vchiq_arm/vchiq_util.c | 32 ------------------- 1 file changed, 32 deletions(-) diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c index 44b954daa74a..4b8554bc647e 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c @@ -84,20 +84,7 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) flush_signals(current); } - /* - * Write to queue->storage must be visible after read from - * queue->read - */ - smp_mb(); - queue->storage[queue->write & (queue->size - 1)] = header; - - /* - * Write to queue->storage must be visible before write to - * queue->write - */ - smp_wmb(); - queue->write++; complete(&queue->push); @@ -112,12 +99,6 @@ VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue) complete(&queue->push); // We haven't removed anything from the queue. - /* - * Read from queue->storage must be visible after read from - * queue->write - */ - smp_rmb(); - return queue->storage[queue->read & (queue->size - 1)]; } @@ -130,20 +111,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) flush_signals(current); } - /* - * Read from queue->storage must be visible after read from - * queue->write - */ - smp_rmb(); - header = queue->storage[queue->read & (queue->size - 1)]; - - /* - * Read from queue->storage must be visible before write to - * queue->read - */ - smp_mb(); - queue->read++; complete(&queue->pop); -- 2.19.1