From patchwork Sat Aug 20 12:56:57 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tudor Ambarus X-Patchwork-Id: 12949684 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 AF093C25B08 for ; Sat, 20 Aug 2022 13:03:28 +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:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version: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=m/ap0f08uwYFZ85KAsNNXqTp+W7VR4da/ouPdWVdveY=; b=sywUxctWwSiYeI nMrq4MbUmWpYRV1Q4JP2E7AAWPB/mGS/QMLYGnDLpOfMgavH4xD9FocasCXQQw39Q2hUnZrwBqC/i hL9+rbGCdBVCLxe3k3CXd0DGUq8DtQw3cT8Qh0etrEcL5EY9G8GwKQ86wpGIsMjW/sqnzah3Nrfgw hyNdtCabIe1tmsCIPxquARNVsIpJ3+1jw8b9iR7wzItzGO0oqN1a+uKjm8Al9k/FreJYTWd4AsgP/ hgDWpR4/tMGbYZu4cTD56BqDN7nML9cK8jhmrqJhtPiuGO8HI5wuJ84nzKYrG1DxMDOAgSeRu5mv5 riYhM5fk/SJlPi//NGVA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oPO7M-00AEve-HB; Sat, 20 Aug 2022 13:02:24 +0000 Received: from esa.microchip.iphmx.com ([68.232.153.233]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oPO3G-00ACbe-Tx for linux-arm-kernel@lists.infradead.org; Sat, 20 Aug 2022 12:58:12 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1661000290; x=1692536290; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=DoY/kmwSNdvclyuGL7rhO4ysuRQmmM1yEVWM6puZ2Hc=; b=Ar8rgU1Eqv4f92B9agTc6xDZB7owCzc0YGJbA7Y/IPfgtdmsixDZR+/F 3VHe5nnCJKobtnUH5USAA7GpbKkG2OD5bgAHdPh/uc3J/FfyChVz+MiUf 2KhKz2hq9hzJUePM5XfoO3TpcU2lmz1Uo6BZF+LmA8tFtOfQKofpLRN0C u+3Wv+3vZfVcchcuzLe9orIDQbP5KUTpRNZmQhJyhgQs+8KhCPIbzq6ng Looxu53LUIEgDbTzVGEkdLfayLE5d0rz+j/r6VcxY7kFvCOEJb1vGRLHC GyKpglpdDOMbDovgIoOyXVpno6nGU4SDrGP1BgrgoyWel0UmEWKV3e/gi Q==; X-IronPort-AV: E=Sophos;i="5.93,251,1654585200"; d="scan'208";a="177188241" Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa3.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 20 Aug 2022 05:58:10 -0700 Received: from chn-vm-ex02.mchp-main.com (10.10.85.144) by chn-vm-ex03.mchp-main.com (10.10.85.151) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.12; Sat, 20 Aug 2022 05:58:07 -0700 Received: from ROB-ULT-M18064N.mchp-main.com (10.10.115.15) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server id 15.1.2507.12 via Frontend Transport; Sat, 20 Aug 2022 05:58:04 -0700 From: Tudor Ambarus To: , , , Subject: [PATCH 13/33] dmaengine: at_hdmac: Fix concurrency problems by removing atc_complete_all() Date: Sat, 20 Aug 2022 15:56:57 +0300 Message-ID: <20220820125717.588722-14-tudor.ambarus@microchip.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220820125717.588722-1-tudor.ambarus@microchip.com> References: <20220820125717.588722-1-tudor.ambarus@microchip.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220820_055811_028865_D87B2A6B X-CRM114-Status: GOOD ( 14.35 ) 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: , Cc: tudor.ambarus@microchip.com, linux-kernel@vger.kernel.org, maciej.sosnowski@intel.com, mripard@kernel.org, torfl6749@gmail.com, ludovic.desroches@microchip.com, stable@vger.kernel.org, dmaengine@vger.kernel.org, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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/ --- drivers/dma/at_hdmac.c | 49 ++++-------------------------------------- 1 file changed, 4 insertions(+), 45 deletions(-) diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index aeb241832c52..10424a6fcbbf 100644 --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -920,42 +920,6 @@ 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->dma_chan), "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 @@ -963,25 +927,20 @@ 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->dma_chan), "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); }