From patchwork Sat Aug 20 12:57:00 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tudor Ambarus X-Patchwork-Id: 12949654 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 580C7C3F6B0 for ; Sat, 20 Aug 2022 12:59:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347277AbiHTM7X (ORCPT ); Sat, 20 Aug 2022 08:59:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347106AbiHTM64 (ORCPT ); Sat, 20 Aug 2022 08:58:56 -0400 Received: from esa.microchip.iphmx.com (esa.microchip.iphmx.com [68.232.154.123]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC6BD2B1A1; Sat, 20 Aug 2022 05:58:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1661000301; x=1692536301; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=PCoOcNi4gHsugNwjMnoPFdo3B9vCHVSc5ivgIMrs5J0=; b=gyWBDmti1ik4wYqA1PbYL7UpJJjf4UEKzC9XzeXqhbzhPKlEdAiD8qg+ DLOwQLzOEnZYZzCB6NO6Yfg+pilWtFyAvP9WWN1O3lwvUDOjoNiP0uYXG SL6Z03ts8tukCGMkBu2LDffs3nELttVlFr5iAYpymguk4ASkSbVuqkrLC S3G4bIjoRpJNOUIapMsuFtIf/LJtbG2G1voeDkk+2JIK7uN51FeBgmAZX pO3sL79H66VodVF9H6rM1VGtYDZNP/PsPmcnBkNilOJj1W0jOMONIriuu YGXMoM4urKP2wzp352lp1SFzKtJQIbnv0X0xDaOcn0p4BgZ0xKA6umhNF Q==; X-IronPort-AV: E=Sophos;i="5.93,251,1654585200"; d="scan'208";a="109911541" Received: from unknown (HELO email.microchip.com) ([170.129.1.10]) by esa6.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 20 Aug 2022 05:58:18 -0700 Received: from chn-vm-ex02.mchp-main.com (10.10.87.72) by chn-vm-ex02.mchp-main.com (10.10.87.72) 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 05:58:18 -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 05:58:15 -0700 From: Tudor Ambarus To: , , , CC: , , , , , , , , , , Subject: [PATCH 16/33] dmaengine: at_hdmac: Fix concurrency over the active list Date: Sat, 20 Aug 2022 15:57:00 +0300 Message-ID: <20220820125717.588722-17-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 Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org The tasklet did not held the channel lock when retrieving the first active descriptor, causing concurrency problems if issue_pending() was called in between. If issue_pending() was called exactly after the lock was released in the tasklet, atc_chain_complete() could complete a descriptor for which the controller has not yet raised an interrupt. Fixes: dc78baa2b90b ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller") Reported-by: Peter Rosin Cc: stable@vger.kernel.org Signed-off-by: Tudor Ambarus Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/ --- drivers/dma/at_hdmac.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index c2b3d7b63920..635c3be74399 100644 --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -897,8 +897,6 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc) if (!atc_chan_is_cyclic(atchan)) dma_cookie_complete(txd); - /* Remove transfer node from the active list. */ - list_del_init(&desc->desc_node); spin_unlock_irqrestore(&atchan->lock, flags); dma_descriptor_unmap(txd); @@ -930,6 +928,7 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc) */ static void atc_advance_work(struct at_dma_chan *atchan) { + struct at_desc *desc; unsigned long flags; dev_vdbg(chan2dev(&atchan->dma_chan), "advance_work\n"); @@ -937,9 +936,12 @@ static void atc_advance_work(struct at_dma_chan *atchan) spin_lock_irqsave(&atchan->lock, flags); if (atc_chan_is_enabled(atchan) || list_empty(&atchan->active_list)) return spin_unlock_irqrestore(&atchan->lock, flags); - spin_unlock_irqrestore(&atchan->lock, flags); - atc_chain_complete(atchan, atc_first_active(atchan)); + desc = atc_first_active(atchan); + /* Remove the transfer node from the active list. */ + list_del_init(&desc->desc_node); + spin_unlock_irqrestore(&atchan->lock, flags); + atc_chain_complete(atchan, desc); /* advance work */ spin_lock_irqsave(&atchan->lock, flags);