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 A9A3EC4332F for ; Mon, 14 Nov 2022 11:12:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236534AbiKNLMV (ORCPT ); Mon, 14 Nov 2022 06:12:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236793AbiKNLLu (ORCPT ); Mon, 14 Nov 2022 06:11:50 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 081B424F19 for ; Mon, 14 Nov 2022 03:08:53 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 99E18B80DE1 for ; Mon, 14 Nov 2022 11:08:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C007DC433D6; Mon, 14 Nov 2022 11:08:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1668424131; bh=CRI7axk2BZu6Ea3CMFqWR1XOLvxyDXjAOEi/7sPO1wQ=; h=Subject:To:Cc:From:Date:From; b=LDA2hlFbL2g9ceWa+5fDh0DkZAjRK3D8q40VjAeoQMb5Y4LwfFH+tYrsiSrSh667S xwLe5iNuusAD/rxUm+qTR+8v2H9NHM+U4nJk8EggdUesBwA+OK3SQS9zK9LLksQmi8 QyfvUKiFgC1K6yrfxhVb4z1BoyVVtNIA0PwajeWI= Subject: FAILED: patch "[PATCH] dmaengine: at_hdmac: Fix concurrency problems by removing" failed to apply to 4.9-stable tree To: tudor.ambarus@microchip.com, nicolas.ferre@microchip.com, peda@axentia.se, vkoul@kernel.org Cc: From: Date: Mon, 14 Nov 2022 12:08:39 +0100 Message-ID: <1668424119923@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . Possible dependencies: c6babed879fb ("dmaengine: at_hdmac: Fix concurrency problems by removing atc_complete_all()") 078a6506141a ("dmaengine: at_hdmac: Fix deadlocks") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From c6babed879fbe82796a601bf097649e07382db46 Mon Sep 17 00:00:00 2001 From: Tudor Ambarus Date: Tue, 25 Oct 2022 12:02:41 +0300 Subject: [PATCH] dmaengine: at_hdmac: Fix concurrency problems by removing atc_complete_all() atc_complete_all() had concurrency bugs, thus remove it: 1/ atc_complete_all() in its entirety was buggy, as when the atchan->queue list (the one that contains descriptors that are not yet issued to the hardware) contained descriptors, it fired just the first from the atchan->queue, but moved all the desc from atchan->queue to atchan->active_list and considered them all as fired. This could result in calling the completion of a descriptor that was not yet issued to the hardware. 2/ when in tasklet at atc_advance_work() time, atchan->active_list was queried without holding the lock of the chan. This can result in atchan->active_list concurrency problems between the tasklet and issue_pending(). Fixes: dc78baa2b90b ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller") Reported-by: Peter Rosin Signed-off-by: Tudor Ambarus Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/ Acked-by: Nicolas Ferre Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com Link: https://lore.kernel.org/r/20221025090306.297886-8-tudor.ambarus@microchip.com Signed-off-by: Vinod Koul diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index deb4c6027436..f1e6fa6af6c2 100644 --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -485,42 +485,6 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc) dma_run_dependencies(txd); } -/** - * atc_complete_all - finish work for all transactions - * @atchan: channel to complete transactions for - * - * Eventually submit queued descriptors if any - * - * Assume channel is idle while calling this function - * Called with atchan->lock held and bh disabled - */ -static void atc_complete_all(struct at_dma_chan *atchan) -{ - struct at_desc *desc, *_desc; - LIST_HEAD(list); - unsigned long flags; - - dev_vdbg(chan2dev(&atchan->chan_common), "complete all\n"); - - spin_lock_irqsave(&atchan->lock, flags); - - /* - * Submit queued descriptors ASAP, i.e. before we go through - * the completed ones. - */ - if (!list_empty(&atchan->queue)) - atc_dostart(atchan, atc_first_queued(atchan)); - /* empty active_list now it is completed */ - list_splice_init(&atchan->active_list, &list); - /* empty queue list by moving descriptors (if any) to active_list */ - list_splice_init(&atchan->queue, &atchan->active_list); - - spin_unlock_irqrestore(&atchan->lock, flags); - - list_for_each_entry_safe(desc, _desc, &list, desc_node) - atc_chain_complete(atchan, desc); -} - /** * atc_advance_work - at the end of a transaction, move forward * @atchan: channel where the transaction ended @@ -528,25 +492,20 @@ static void atc_complete_all(struct at_dma_chan *atchan) static void atc_advance_work(struct at_dma_chan *atchan) { unsigned long flags; - int ret; dev_vdbg(chan2dev(&atchan->chan_common), "advance_work\n"); spin_lock_irqsave(&atchan->lock, flags); - ret = atc_chan_is_enabled(atchan); + if (atc_chan_is_enabled(atchan) || list_empty(&atchan->active_list)) + return spin_unlock_irqrestore(&atchan->lock, flags); spin_unlock_irqrestore(&atchan->lock, flags); - if (ret) - return; - - if (list_empty(&atchan->active_list) || - list_is_singular(&atchan->active_list)) - return atc_complete_all(atchan); atc_chain_complete(atchan, atc_first_active(atchan)); /* advance work */ spin_lock_irqsave(&atchan->lock, flags); - atc_dostart(atchan, atc_first_active(atchan)); + if (!list_empty(&atchan->active_list)) + atc_dostart(atchan, atc_first_active(atchan)); spin_unlock_irqrestore(&atchan->lock, flags); }