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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E2F1C4332F for ; Mon, 21 Mar 2022 17:02:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351565AbiCURDZ (ORCPT ); Mon, 21 Mar 2022 13:03:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58202 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351583AbiCURDI (ORCPT ); Mon, 21 Mar 2022 13:03:08 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B71D9132EB7; Mon, 21 Mar 2022 10:01:42 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 536EC61451; Mon, 21 Mar 2022 17:01:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A43BC340E8; Mon, 21 Mar 2022 17:01:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1647882101; bh=z74tmM91Um9X1h7Fhx54Fbs7WMs3ywKR9k3rFYogmiA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=p4DM2ufydUB+hlToCdfm9R6miNisFSTGqpnrdwux16BgmTvTDhbfRvFmzM5L6vW1v ayIg+HMlsnwDpVZxQTp1Hl2/u0BCRxVQF6g+6BdlnqYMpfhg5GHtleX+McUaKIbjaC mQrv/1pa8VWuzusofQFkwlRX9tyvINDCzaRiJ5ouiWwH6/osxtCmhdwclNWV3Ypz1d uDSngg5GD5fQUJgAGSdxQhsb2AmQokTUSxCyIUWMnFUfigRdEHSV79eNouy/TE/wsp /p71KygkDPu0CUEGzDomV89Q+nuLH7PQ7H2yf4hvCBoI+Kib69tr+h2SEioxROAzNm DoWkvMr02pTSA== Date: Mon, 21 Mar 2022 11:01:39 -0600 From: Keith Busch To: Sven Peter Cc: Jens Axboe , Christoph Hellwig , Sagi Grimberg , Hector Martin , Alyssa Rosenzweig , Rob Herring , Arnd Bergmann , Marc Zyngier , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: [PATCH 6/9] nvme-apple: Add initial Apple SoC NVMe driver Message-ID: References: <20220321165049.35985-1-sven@svenpeter.dev> <20220321165049.35985-7-sven@svenpeter.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220321165049.35985-7-sven@svenpeter.dev> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 21, 2022 at 05:50:46PM +0100, Sven Peter wrote: > +static bool apple_nvme_poll_cq(struct apple_nvme_queue *q, > + struct io_comp_batch *iob) > +{ > + bool found = false; > + > + while (apple_nvme_cqe_pending(q)) { > + found = true; > + > + /* > + * load-load control dependency between phase and the rest of > + * the cqe requires a full read memory barrier > + */ > + dma_rmb(); > + apple_nvme_handle_cqe(q, iob, q->cq_head); > + apple_nvme_update_cq_head(q); > + } > + > + if (found) > + writel_relaxed(q->cq_head, q->cq_db); Doesn't a relaxed write mean that a subsequent write can bypass the previous? If so, that sounds like it can corrupt the cq head. 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 8CFFEC433F5 for ; Mon, 21 Mar 2022 17:09:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=T1DxWRbovSBBVCEPqHXiMW5b1eCFNEX6D24Esld3E8k=; b=zb3ogZc3sSMXCt bC+CBt6R7ZwEt1oOdCUisDLElnG3FGvfYMueMGpJxIaBGeYeNDCFwdJvh0/rAH7lADq8o9JlRRwAe xBw1etb4bcPuiwQZFe3GAF31ZnS295s48QO+Egs8lJLIfAi5FBEcaeb5ICH/tsGgReqVPVABo5+Lg 5CQ3VLRKtBwOz/XvuG9rTSfBJObs29Y1meTNZnfHexQ/r+saA6CnknFTNvLHMjLXVm6o02ndIwapp 1AQNghkGmBXh5QGIIq+pICT+nYX5EBv0LX6kEnTPw1H3QLn/Wl4j1D35hLZ2OZO7x3xj0gH1yeGZZ hOXEHMqs04USe38qyL+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nWLVh-008Whk-GJ; Mon, 21 Mar 2022 17:08:04 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nWLPa-008UXl-S9; Mon, 21 Mar 2022 17:01:44 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 571C961452; Mon, 21 Mar 2022 17:01:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A43BC340E8; Mon, 21 Mar 2022 17:01:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1647882101; bh=z74tmM91Um9X1h7Fhx54Fbs7WMs3ywKR9k3rFYogmiA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=p4DM2ufydUB+hlToCdfm9R6miNisFSTGqpnrdwux16BgmTvTDhbfRvFmzM5L6vW1v ayIg+HMlsnwDpVZxQTp1Hl2/u0BCRxVQF6g+6BdlnqYMpfhg5GHtleX+McUaKIbjaC mQrv/1pa8VWuzusofQFkwlRX9tyvINDCzaRiJ5ouiWwH6/osxtCmhdwclNWV3Ypz1d uDSngg5GD5fQUJgAGSdxQhsb2AmQokTUSxCyIUWMnFUfigRdEHSV79eNouy/TE/wsp /p71KygkDPu0CUEGzDomV89Q+nuLH7PQ7H2yf4hvCBoI+Kib69tr+h2SEioxROAzNm DoWkvMr02pTSA== Date: Mon, 21 Mar 2022 11:01:39 -0600 From: Keith Busch To: Sven Peter Cc: Jens Axboe , Christoph Hellwig , Sagi Grimberg , Hector Martin , Alyssa Rosenzweig , Rob Herring , Arnd Bergmann , Marc Zyngier , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org Subject: Re: [PATCH 6/9] nvme-apple: Add initial Apple SoC NVMe driver Message-ID: References: <20220321165049.35985-1-sven@svenpeter.dev> <20220321165049.35985-7-sven@svenpeter.dev> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220321165049.35985-7-sven@svenpeter.dev> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220321_100142_989215_F1552563 X-CRM114-Status: GOOD ( 14.67 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Mar 21, 2022 at 05:50:46PM +0100, Sven Peter wrote: > +static bool apple_nvme_poll_cq(struct apple_nvme_queue *q, > + struct io_comp_batch *iob) > +{ > + bool found = false; > + > + while (apple_nvme_cqe_pending(q)) { > + found = true; > + > + /* > + * load-load control dependency between phase and the rest of > + * the cqe requires a full read memory barrier > + */ > + dma_rmb(); > + apple_nvme_handle_cqe(q, iob, q->cq_head); > + apple_nvme_update_cq_head(q); > + } > + > + if (found) > + writel_relaxed(q->cq_head, q->cq_db); Doesn't a relaxed write mean that a subsequent write can bypass the previous? If so, that sounds like it can corrupt the cq head. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel