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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 515DAC7618B for ; Fri, 26 Jul 2019 13:48:02 +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 2566822CD8 for ; Fri, 26 Jul 2019 13:48:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="jEVtoXK6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2566822CD8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=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:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To: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:List-Owner; bh=WPd5i1hJTX48hvSpHL+hL/V7RpRJfspNTm8jej/6tws=; b=jEVtoXK6M/u5vC3z3zWIFfnJNg y6V6qTqSDXyBb7Q7xB8M9AuhsJTkf/cXrzAJSlQP/AI8OFbVkpKh4ZDXXiUIlto9cOn9s57h1hwdn 7wyyfnytx8w8kfn6/nP3o9jOH7LyC9KY3E7difda35IEcw+MEe4kn5KsMWtRhXvOOz9JvRRkqEWqc QA0fdAZ7m/nUyRq9y7hVCc3yJoDsqmyjFiNOLqds5SxT0ImgCZvTITotXNrmiHsM1B5r9BLk8kjSW cVGuYjEtNO4bozRWmQYuyZBeZ0bU1/kvwIgGEwpjOAlltIjG8VABq7Fvr+VzAjYfCOOh8E5nv8Y0z 7NgpwgNg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hr0Zd-0004pI-MD; Fri, 26 Jul 2019 13:47:53 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hr0Y1-0003Gb-5Q for linux-arm-kernel@lists.infradead.org; Fri, 26 Jul 2019 13:46:14 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E3AE8152D; Fri, 26 Jul 2019 06:46:12 -0700 (PDT) Received: from usa.arm.com (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id ABB1D3F694; Fri, 26 Jul 2019 06:46:11 -0700 (PDT) From: Sudeep Holla To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 6/6] firmware: arm_scmi: Check if platform has released shmem before using Date: Fri, 26 Jul 2019 14:45:31 +0100 Message-Id: <20190726134531.8928-7-sudeep.holla@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190726134531.8928-1-sudeep.holla@arm.com> References: <20190726134531.8928-1-sudeep.holla@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190726_064613_488044_C3161ADB X-CRM114-Status: GOOD ( 10.92 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peng Fan , Etienne Carriere , linux-kernel@vger.kernel.org, Bo Zhang , Jim Quinlan , Sudeep Holla , Gaku Inami , Volodymyr Babchuk MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Sometimes platfom may take too long to respond to the command and OS might timeout before platform transfer the ownership of the shared memory region to the OS with the response. Since the mailbox channel associated with the channel is freed and new commands are dispatch on the same channel, OS needs to wait until it gets back the ownership. If not, either OS may end up overwriting the platform response for the last command(which is fine as OS timed out that command) or platform might overwrite the payload for the next command with the response for the old. The latter is problematic as platform may end up interpretting the response as the payload. In order to avoid such race, let's wait until the OS gets back the ownership before we prepare the shared memory with the payload for the next command. Reported-by: Jim Quinlan Signed-off-by: Sudeep Holla --- drivers/firmware/arm_scmi/driver.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 69bf85fea967..765573756987 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -265,6 +265,14 @@ static void scmi_tx_prepare(struct mbox_client *cl, void *m) struct scmi_chan_info *cinfo = client_to_scmi_chan_info(cl); struct scmi_shared_mem __iomem *mem = cinfo->payload; + /* + * Ideally channel must be free by now unless OS timeout last + * request and platform continued to process the same, wait + * until it releases the shared memory, otherwise we may endup + * overwriting it's response with new command payload or vice-versa + */ + spin_until_cond(ioread32(&mem->channel_status) & + SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE); /* Mark channel busy + clear error */ iowrite32(0x0, &mem->channel_status); iowrite32(t->hdr.poll_completion ? 0 : SCMI_SHMEM_FLAG_INTR_ENABLED, -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel