From patchwork Mon May 9 10:00:56 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Robin Murphy X-Patchwork-Id: 9044231 X-Patchwork-Delegate: geert@linux-m68k.org Return-Path: X-Original-To: patchwork-linux-renesas-soc@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 8CFD9BF29F for ; Mon, 9 May 2016 10:01:03 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 69E9D20142 for ; Mon, 9 May 2016 10:01:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1CDC7200F2 for ; Mon, 9 May 2016 10:01:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751248AbcEIKBA (ORCPT ); Mon, 9 May 2016 06:01:00 -0400 Received: from foss.arm.com ([217.140.101.70]:36623 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751080AbcEIKBA (ORCPT ); Mon, 9 May 2016 06:01:00 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D2C993C; Mon, 9 May 2016 03:01:09 -0700 (PDT) Received: from [10.1.205.154] (e104324-lin.cambridge.arm.com [10.1.205.154]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2E7673F51B; Mon, 9 May 2016 03:00:58 -0700 (PDT) Subject: Re: [PATCH 0/2] Fix incorrect warning from dma-debug To: =?UTF-8?Q?Niklas_S=c3=b6derlund?= , linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, dmaengine@vger.kernel.org References: <1462705196-10857-1-git-send-email-niklas.soderlund+renesas@ragnatech.se> <57305A4B.70401@arm.com> Cc: linux-renesas-soc@vger.kernel.org, will.deacon@arm.com, linux-kernel@vger.kernel.org From: Robin Murphy Message-ID: <57305FD8.7070006@arm.com> Date: Mon, 9 May 2016 11:00:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <57305A4B.70401@arm.com> Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org X-Spam-Status: No, score=-9.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 09/05/16 10:37, Robin Murphy wrote: > Hi Niklas, > > On 08/05/16 11:59, Niklas Söderlund wrote: >> Hi, >> >> While using CONFIG_DMA_API_DEBUG i came across this warning which I >> think is a false positive. As shown dma_sync_single_for_device() are >> called from the dma_map_single() call path. This triggers the warning >> since the dma-debug code have not yet been made aware of the mapping. > > Almost right ;) The thing being mapped (the SPI device's buffer) and the > thing being synced (the IOMMU's PTE) are entirely unrelated. Due to the > current of_iommu_init() setup, the IOMMU is probed long before > dma_debug_init() gets called, therefore DMA debug is missing entries for > some of the initial page table mappings and gets confused when we update > them later. > >> I try to solve this by introducing __dma_sync_single_for_device() which >> do not call into the dma-debug code. I'm no expert and this might be a >> bad way of solving the problem but it allowed me to keep working. > > The simple fix should be to just call dma_debug_init() from a > sufficiently earlier initcall level. The best would be to sort out a > proper device dependency order to avoid the whole early-IOMMU-creation > thing entirely. A tangential idea, as Will just suggested to me, would be to make this false-positive situation more explicit, something like (untested): ---8<--- --->8--- but it seems like this a sufficiently rare case that it's probably not worth cluttering up the code for. Robin. >> ------------[ cut here ]------------ >> WARNING: CPU: 0 PID: 1 at lib/dma-debug.c:1209 check_sync+0x154/0x5e4 >> ipmmu-vmsa e6740000.mmu: DMA-API: device driver tries to sync DMA >> memory it has not allocated [device address=0x000000006e89b008] >> [size=8 bytes] >> CPU: 0 PID: 1 Comm: swapper/0 Not tainted >> 4.6.0-rc5-00012-g52e78c1-dirty #1 >> Hardware name: Generic R8A7791 (Flattened Device Tree) >> Backtrace: >> [] (dump_backtrace) from [] (show_stack+0x18/0x1c) >> r7:c03ebad0 r6:00000009 r5:60000093 r4:00000000 >> [] (show_stack) from [] (dump_stack+0x84/0xa4) >> [] (dump_stack) from [] (__warn+0xd0/0x100) >> r5:00000000 r4:ef05dac8 >> [] (__warn) from [] (warn_slowpath_fmt+0x40/0x48) >> r9:00010000 r8:00000000 r7:c0c69c40 r6:c0c02754 r5:ef05db78 r4:ef222810 >> [] (warn_slowpath_fmt) from [] >> (check_sync+0x154/0x5e4) >> r3:c0945b6f r2:c0936e85 >> [] (check_sync) from [] >> (debug_dma_sync_single_for_device+0x64/0x70) >> r10:00000009 r9:0000000c r8:ee89b008 r7:00000000 r6:6e89b008 >> r5:00000000 >> r4:6e89b008 >> [] (debug_dma_sync_single_for_device) from [] >> (__arm_lpae_set_pte.part.0+0x80/0x8c) >> r5:00000001 r4:ef222810 >> [] (__arm_lpae_set_pte.part.0) from [] >> (__arm_lpae_map+0x298/0x2f0) >> r7:00000008 r6:ef25e000 r4:ee898500 >> [] (__arm_lpae_map) from [] (arm_lpae_map+0xcc/0xe4) >> r10:c0465f40 r9:00001000 r8:40000000 r7:00000000 r6:6f25c000 >> r5:00000000 >> r4:000008c0 >> [] (arm_lpae_map) from [] (ipmmu_map+0x38/0x40) >> r7:40000000 r6:00000000 r5:00001000 r4:c0465a4c >> [] (ipmmu_map) from [] (iommu_map+0xf8/0x15c) >> r4:ee895608 >> [] (iommu_map) from [] >> (arm_coherent_iommu_map_page+0x1d4/0x2d4) >> r10:ef386940 r9:00001000 r8:00000000 r7:00000000 r6:40000000 >> r5:00000000 >> r4:00000000 >> [] (arm_coherent_iommu_map_page) from [] >> (arm_iommu_map_page+0x6c/0x74) >> r10:c0c61f44 r9:ef19d210 r8:00000001 r7:00001000 r6:00000000 >> r5:ec5ddb80 >> r4:00000000 >> [] (arm_iommu_map_page) from [] >> (sh_msiof_spi_probe+0x430/0x7b0) >> r9:00000000 r8:c0213624 r7:ef19d210 r6:ef242800 r5:ef1b4010 r4:ef242af0 >> [] (sh_msiof_spi_probe) from [] >> (platform_drv_probe+0x58/0xa8) >> r10:00000000 r9:00000000 r8:c0c1f8d4 r7:c0c7e910 r6:c0c1f8d4 >> r5:ef1b4010 >> r4:c04f7934 >> [] (platform_drv_probe) from [] >> (driver_probe_device+0x13c/0x2a4) >> r7:c0c7e910 r6:00000000 r5:c0c7e900 r4:ef1b4010 >> [] (driver_probe_device) from [] >> (__driver_attach+0x88/0xac) >> r9:c0c34000 r8:c0a3c010 r7:c0c1cf08 r6:c0c1f8d4 r5:ef1b4044 r4:ef1b4010 >> [] (__driver_attach) from [] >> (bus_for_each_dev+0x74/0x98) >> r7:c0c1cf08 r6:c049e8f0 r5:c0c1f8d4 r4:00000000 >> [] (bus_for_each_dev) from [] >> (driver_attach+0x20/0x28) >> r6:ef1cc200 r5:00000000 r4:c0c1f8d4 >> [] (driver_attach) from [] >> (bus_add_driver+0xd4/0x1e4) >> [] (bus_add_driver) from [] >> (driver_register+0xa4/0xe8) >> r7:c0a3c010 r6:00000000 r5:c0a1e400 r4:c0c1f8d4 >> [] (driver_register) from [] >> (__platform_driver_register+0x38/0x4c) >> r5:c0a1e400 r4:ee958fc0 >> [] (__platform_driver_register) from [] >> (sh_msiof_spi_drv_init+0x18/0x20) >> [] (sh_msiof_spi_drv_init) from [] >> (do_one_initcall+0x10c/0x1c0) >> [] (do_one_initcall) from [] >> (kernel_init_freeable+0x128/0x1f4) >> r9:c0c34000 r8:c0c34000 r7:c0a47e60 r6:c0a3c83c r5:000000bd r4:00000006 >> [] (kernel_init_freeable) from [] >> (kernel_init+0x10/0x118) >> r9:00000000[ 1.879529] ata1: link resume succeeded after 1 retries >> r8:00000000 r7:00000000 r6:00000000 r5:c071066c r4:00000000 >> [] (kernel_init) from [] (ret_from_fork+0x14/0x2c) >> r5:c071066c r4:00000000 >> ---[ end trace 6eb9a3df3009d491 ]--- >> >> Niklas Söderlund (2): >> dma-mapping: add __dma_sync_single_for_device() >> iommu/io-pgtable-arm: use __dma_sync_single_for_device() >> >> drivers/iommu/io-pgtable-arm.c | 2 +- >> include/linux/dma-mapping.h | 9 ++++++++- >> 2 files changed, 9 insertions(+), 2 deletions(-) >> >> -- >> 2.8.2 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >> > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu diff --git a/lib/dma-debug.c b/lib/dma-debug.c index 4a1515f4b452..e16684a4ce86 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -107,7 +107,8 @@ static bool dma_debug_initialized __read_mostly; static inline bool dma_debug_disabled(void) { - return global_disable || !dma_debug_initialized; + return global_disable || WARN_ONCE(!dma_debug_initialized, + "early DMA-API call not tracked"); } /* Global error count */