From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938331AbeE1Lap (ORCPT ); Mon, 28 May 2018 07:30:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:33860 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1424002AbeE1LOi (ORCPT ); Mon, 28 May 2018 07:14:38 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nguyen Viet Dung , Yoshihiro Shimoda , Vinod Koul , Sasha Levin Subject: [PATCH 4.16 212/272] dmaengine: rcar-dmac: Check the done lists in rcar_dmac_chan_get_residue() Date: Mon, 28 May 2018 12:04:05 +0200 Message-Id: <20180528100258.317133820@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180528100240.256525891@linuxfoundation.org> References: <20180528100240.256525891@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yoshihiro Shimoda [ Upstream commit 3e081628d510b2ddbe493371d9c574d9275da17e ] This patch fixes an issue that a race condition happens between a client driver and the rcar-dmac driver: - The rcar_dmac_isr_transfer_end() is called. - The done list appears, and desc.running is the next active list. - rcar_dmac_chan_get_residue() is called by a client driver before rcar_dmac_isr_channel_thread() is called. - The rcar_dmac_chan_get_residue() will not find any descriptors. - And, the following WARNING happens: WARN(1, "No descriptor for cookie!"); The sh-sci driver with HSCIF (921,600bps) on R-Car H3 can cause this situation. So, this patch checks the done lists in rcar_dmac_chan_get_residue() and returns zero if the done lists has the argument cookie. Tested-by: Nguyen Viet Dung Signed-off-by: Yoshihiro Shimoda Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/dma/sh/rcar-dmac.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -1301,8 +1301,17 @@ static unsigned int rcar_dmac_chan_get_r * If the cookie doesn't correspond to the currently running transfer * then the descriptor hasn't been processed yet, and the residue is * equal to the full descriptor size. + * Also, a client driver is possible to call this function before + * rcar_dmac_isr_channel_thread() runs. In this case, the "desc.running" + * will be the next descriptor, and the done list will appear. So, if + * the argument cookie matches the done list's cookie, we can assume + * the residue is zero. */ if (cookie != desc->async_tx.cookie) { + list_for_each_entry(desc, &chan->desc.done, node) { + if (cookie == desc->async_tx.cookie) + return 0; + } list_for_each_entry(desc, &chan->desc.pending, node) { if (cookie == desc->async_tx.cookie) return desc->size;