From patchwork Tue Oct 25 09:02:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tudor Ambarus X-Patchwork-Id: 13018779 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 D9B17C04A95 for ; Tue, 25 Oct 2022 09:04:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231655AbiJYJEI (ORCPT ); Tue, 25 Oct 2022 05:04:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57360 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231985AbiJYJDx (ORCPT ); Tue, 25 Oct 2022 05:03:53 -0400 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.154.123]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB14715A958; Tue, 25 Oct 2022 02:03:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1666688616; x=1698224616; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=vzbP7zNV4WWjKYut34MMlg3SmrYxTKJy5nmzawe3BVg=; b=TIBXgt5cbTIXZZzFlRERFRiDVwV1+aSXBB9c15KvDWOG8jmWLeT7jjL9 wuDqncquHYlLdukwAonG/PQxVzaYd0MBjULichILn8ikuZnxmhMPT01ly xzH/NoQlU+tKBFC8abxjBHbNydde+FVPya9og/MuVFKz233QBaZTtTVsA Zy9RmLF5SGw6CSUwTqfEfejLtPHxei2FTS12lYl6L6RGYevhwe4GAx+X6 49aoKynDi2XzI9Cq4iOnlsSFzkKT5e4UrRTwhEaew4qB2vKvn9fQowzQa XF0MrXvJBP6/Rm9JRX8QsG81GPOn2KkmJ7DPiVlDuJeNoLqybRGVYPwGG A==; X-IronPort-AV: E=Sophos;i="5.95,211,1661842800"; d="scan'208";a="120221261" Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa6.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 25 Oct 2022 02:03:33 -0700 Received: from chn-vm-ex03.mchp-main.com (10.10.85.151) by chn-vm-ex04.mchp-main.com (10.10.85.152) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.12; Tue, 25 Oct 2022 02:03:33 -0700 Received: from ROB-ULT-M18064N.mchp-main.com (10.10.115.15) by chn-vm-ex03.mchp-main.com (10.10.85.151) with Microsoft SMTP Server id 15.1.2507.12 via Frontend Transport; Tue, 25 Oct 2022 02:03:31 -0700 From: Tudor Ambarus To: , , CC: , , , , , , , "Tudor Ambarus" , Subject: [PATCH v2 07/32] dmaengine: at_hdmac: Fix concurrency problems by removing atc_complete_all() Date: Tue, 25 Oct 2022 12:02:41 +0300 Message-ID: <20221025090306.297886-8-tudor.ambarus@microchip.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221025090306.297886-1-tudor.ambarus@microchip.com> References: <20221025090306.297886-1-tudor.ambarus@microchip.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.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 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); }