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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 12878C4360F for ; Thu, 4 Apr 2019 09:19:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D879420657 for ; Thu, 4 Apr 2019 09:19:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369595; bh=DrQJXkpVrW4dZ29PIH8fHDknVTau9TTwxIDz9sCEYzg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=IZdcjo3B9oqZYLgF+f7uugeTH8wqsHwZVjZGdGwY8U0YelkJQVafBCriBUVaoeLQ4 6C1W27i32qoeqkOojFJJanqCv05+VhX85L5Wig7QGNhd8Y3gT+ovS9ROKdKs5M7wvT yNG5WfMa6xiIo2NmYG/Jt1mrmAFFLN+DR66XzZWI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388392AbfDDJTy (ORCPT ); Thu, 4 Apr 2019 05:19:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:59730 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388300AbfDDJRu (ORCPT ); Thu, 4 Apr 2019 05:17:50 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 A0AFB20820; Thu, 4 Apr 2019 09:17:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554369470; bh=DrQJXkpVrW4dZ29PIH8fHDknVTau9TTwxIDz9sCEYzg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xysiK8x4BXa4Md21lfUtxPwOT+io0Jj0OOU4EY6UDPdAkyKtdvqr8ByZrykA+e9fp YAET0hqZJGx/Mh5A9ogsl0b+e5isALpsaHJz3rIRTQhj8MpHgLgH32o7Yo7txiHJ4A ULMlI3OmQ3/Tk+TRFMbNDGaMCZUm6ik9irDOqplc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dmitry Osipenko , Ben Dooks , Jon Hunter , Vinod Koul , Sasha Levin Subject: [PATCH 5.0 236/246] dmaengine: tegra: avoid overflow of byte tracking Date: Thu, 4 Apr 2019 10:48:56 +0200 Message-Id: <20190404084627.551985183@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190404084619.236418459@linuxfoundation.org> References: <20190404084619.236418459@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 5.0-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit e486df39305864604b7e25f2a95d51039517ac57 ] The dma_desc->bytes_transferred counter tracks the number of bytes moved by the DMA channel. This is then used to calculate the information passed back in the in the tegra_dma_tx_status callback, which is usually fine. When the DMA channel is configured as continous, then the bytes_transferred counter will increase over time and eventually overflow to become negative so the residue count will become invalid and the ALSA sound-dma code will report invalid hardware pointer values to the application. This results in some users becoming confused about the playout position and putting audio data in the wrong place. To fix this issue, always ensure the bytes_transferred field is modulo the size of the request. We only do this for the case of the cyclic transfer done ISR as anyone attempting to move 2GiB of DMA data in one transfer is unlikely. Note, we don't fix the issue that we should /never/ transfer a negative number of bytes so we could make those fields unsigned. Reviewed-by: Dmitry Osipenko Signed-off-by: Ben Dooks Acked-by: Jon Hunter Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin --- drivers/dma/tegra20-apb-dma.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c index 9a558e30c461..8219ab88a507 100644 --- a/drivers/dma/tegra20-apb-dma.c +++ b/drivers/dma/tegra20-apb-dma.c @@ -636,7 +636,10 @@ static void handle_cont_sngl_cycle_dma_done(struct tegra_dma_channel *tdc, sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq), node); dma_desc = sgreq->dma_desc; - dma_desc->bytes_transferred += sgreq->req_len; + /* if we dma for long enough the transfer count will wrap */ + dma_desc->bytes_transferred = + (dma_desc->bytes_transferred + sgreq->req_len) % + dma_desc->bytes_requested; /* Callback need to be call */ if (!dma_desc->cb_count) -- 2.19.1