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,URIBL_BLOCKED, 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 55C94ECDE44 for ; Fri, 26 Oct 2018 13:48:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22ED120868 for ; Fri, 26 Oct 2018 13:48:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 22ED120868 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 S1727613AbeJZWZr (ORCPT ); Fri, 26 Oct 2018 18:25:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:44790 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727431AbeJZWZq (ORCPT ); Fri, 26 Oct 2018 18:25:46 -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 11A1DB04D; Fri, 26 Oct 2018 13:48:37 +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 12/18] staging: vchiq_util: use completions instead of semaphores Date: Fri, 26 Oct 2018 15:48:07 +0200 Message-Id: <20181026134813.7775-13-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 It is preferred in the kernel to avoid using semaphores to wait for events, as they are optimised for the opposite situation; where the common case is that they are available and may block only occasionally. FYI see this thread: https://lkml.org/lkml/2008/4/11/323. Also completions are semantically more explicit in this case. Signed-off-by: Nicolas Saenz Julienne --- .../interface/vchiq_arm/vchiq_util.c | 16 ++++++++-------- .../interface/vchiq_arm/vchiq_util.h | 6 +++--- 2 files changed, 11 insertions(+), 11 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 2e52f07bbaa9..44b954daa74a 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.c @@ -48,8 +48,8 @@ int vchiu_queue_init(VCHIU_QUEUE_T *queue, int size) queue->write = 0; queue->initialized = 1; - sema_init(&queue->pop, 0); - sema_init(&queue->push, 0); + init_completion(&queue->pop); + init_completion(&queue->push); queue->storage = kcalloc(size, sizeof(VCHIQ_HEADER_T *), GFP_KERNEL); if (!queue->storage) { @@ -80,7 +80,7 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) return; while (queue->write == queue->read + queue->size) { - if (down_interruptible(&queue->pop) != 0) + if (wait_for_completion_interruptible(&queue->pop)) flush_signals(current); } @@ -100,17 +100,17 @@ void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header) queue->write++; - up(&queue->push); + complete(&queue->push); } VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue) { while (queue->write == queue->read) { - if (down_interruptible(&queue->push) != 0) + if (wait_for_completion_interruptible(&queue->push)) flush_signals(current); } - up(&queue->push); // We haven't removed anything from the queue. + complete(&queue->push); // We haven't removed anything from the queue. /* * Read from queue->storage must be visible after read from @@ -126,7 +126,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) VCHIQ_HEADER_T *header; while (queue->write == queue->read) { - if (down_interruptible(&queue->push) != 0) + if (wait_for_completion_interruptible(&queue->push)) flush_signals(current); } @@ -146,7 +146,7 @@ VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue) queue->read++; - up(&queue->pop); + complete(&queue->pop); return header; } diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h index 5a1540d349d3..b226227fe5bc 100644 --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_util.h @@ -35,7 +35,7 @@ #define VCHIQ_UTIL_H #include -#include +#include #include #include #include @@ -60,8 +60,8 @@ typedef struct { int write; int initialized; - struct semaphore pop; - struct semaphore push; + struct completion pop; + struct completion push; VCHIQ_HEADER_T **storage; } VCHIU_QUEUE_T; -- 2.19.1