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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, 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 1A834C4CECD for ; Mon, 27 Apr 2020 19:14:55 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E705720775 for ; Mon, 27 Apr 2020 19:14:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="YYJA8dF2"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="AjgWK/43" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E705720775 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=G+DinzHYVVpPmL83OXFXKIuT9C6yXA72A57hPyiU/iM=; b=YYJA8dF2Snd02w YwQUDS7w8GUu6WOhpvMRKAw6YQFob54cCCFjOegFPY8k3qfxokFw+1bZ4M0k0OFWnkb38dNnLGB1S eIEOZv9+msGNv7USEuFxzkLD2s6SilBNXpOmynlHEOa4/0l9tKKE7XRLTeuvCV8xUaY57xzzq7grv yGbzS8apDumf3pP0lVPdoLos7IaGcqkxhJMLZ/nl0zcQG2PXRTG1uhdT7iSQ7flyeQCR6NnAfipCG GHgnSGFj7pEN9UayjjB2LHz9qM5m2cmFBzexXYnrXTwkqNAKUN8BNxtCIPYjdKxNMokleBqtry7dI MzyFB/Fx/kmXCVvb/8vQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jT9DP-0004Mo-Jt; Mon, 27 Apr 2020 19:14:51 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jT9DM-0004M1-EK for linux-nvme@lists.infradead.org; Mon, 27 Apr 2020 19:14:49 +0000 Received: from dhcp-10-100-145-180.wdl.wdc.com (unknown [199.255.45.60]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AC8AF20775; Mon, 27 Apr 2020 19:14:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588014888; bh=31rG1RZEyCbRlRjmP2QKaN0oUboktt2GkZ4gh1E8iYI=; h=From:To:Cc:Subject:Date:From; b=AjgWK/43uFyMZ1HIXq0ouDuLdtJplhf6UyWf7LCgBQvJbIVmEdWz2u/7gwsZxy1kX dSgUAMprjvIdSSCEljm4s8yj6P+LzFRxxzzSo7VIm1FW8kRSCnXkOZBHdVQJRnNXEx /g37v3sYgZ9azB/8VNZr3/c9FYF2Dg+ASFjVMFU0= From: Keith Busch To: linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me Subject: [PATCH] nvme-pci: remove volatile cqes Date: Mon, 27 Apr 2020 12:14:46 -0700 Message-Id: <20200427191446.2195863-1-kbusch@kernel.org> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200427_121448_499435_17F734C0 X-CRM114-Status: GOOD ( 10.85 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Keith Busch Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org The completion queue entry is not volatile once the phase is confirmed. Remove the volaitle keywords and check the phase using the appropriate READ_ONCE() accessor, allowing the compiler to optimize the remaining completion path. Signed-off-by: Keith Busch --- drivers/nvme/host/pci.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 8ebcf40f04fe..cf386c84588b 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -166,7 +166,7 @@ struct nvme_queue { void *sq_cmds; /* only used for poll queues: */ spinlock_t cq_poll_lock ____cacheline_aligned_in_smp; - volatile struct nvme_completion *cqes; + struct nvme_completion *cqes; dma_addr_t sq_dma_addr; dma_addr_t cq_dma_addr; u32 __iomem *q_db; @@ -908,8 +908,9 @@ static void nvme_pci_complete_rq(struct request *req) /* We read the CQE phase first to check if the rest of the entry is valid */ static inline bool nvme_cqe_pending(struct nvme_queue *nvmeq) { - return (le16_to_cpu(nvmeq->cqes[nvmeq->cq_head].status) & 1) == - nvmeq->cq_phase; + return (le16_to_cpu( + READ_ONCE(nvmeq->cqes[nvmeq->cq_head].status)) & 1) == + nvmeq->cq_phase; } static inline void nvme_ring_cq_doorbell(struct nvme_queue *nvmeq) @@ -930,7 +931,7 @@ static inline struct blk_mq_tags *nvme_queue_tagset(struct nvme_queue *nvmeq) static inline void nvme_handle_cqe(struct nvme_queue *nvmeq, u16 idx) { - volatile struct nvme_completion *cqe = &nvmeq->cqes[idx]; + struct nvme_completion *cqe = &nvmeq->cqes[idx]; struct request *req; if (unlikely(cqe->command_id >= nvmeq->q_depth)) { -- 2.24.1 _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme