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 X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CFDF8C10F11 for ; Wed, 10 Apr 2019 21:59:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A417920674 for ; Wed, 10 Apr 2019 21:59:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726623AbfDJV71 (ORCPT ); Wed, 10 Apr 2019 17:59:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53122 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725982AbfDJV71 (ORCPT ); Wed, 10 Apr 2019 17:59:27 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DA9212C971E; Wed, 10 Apr 2019 21:59:26 +0000 (UTC) Received: from t460p.redhat.com (ovpn-118-18.phx2.redhat.com [10.3.118.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 28A375D704; Wed, 10 Apr 2019 21:59:26 +0000 (UTC) From: Scott Wood To: Christoph Hellwig , Marek Szyprowski , Robin Murphy Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Woodhouse , Scott Wood Subject: [PATCH] dma-debug: Only skip one stackframe entry Date: Wed, 10 Apr 2019 16:59:25 -0500 Message-Id: <20190410215925.8458-1-swood@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 10 Apr 2019 21:59:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With skip set to 1, I get a traceback like this: [ 106.867637] DMA-API: Mapped at: [ 106.870784] afu_dma_map_region+0x2cd/0x4f0 [dfl_afu] [ 106.875839] afu_ioctl+0x258/0x380 [dfl_afu] [ 106.880108] do_vfs_ioctl+0xa9/0x720 [ 106.883688] ksys_ioctl+0x60/0x90 [ 106.887007] __x64_sys_ioctl+0x16/0x20 With the previous value of 2, afu_dma_map_region was being omitted. I suspect that the code paths have simply changed since the value of 2 was chosen a decade ago, but it's also possible that it varies based on which mapping function was used, compiler inlining choices, etc. In any case, it's best to err on the side of skipping less. Signed-off-by: Scott Wood --- kernel/dma/debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c index 45d51e8e26f6..a218e43cc382 100644 --- a/kernel/dma/debug.c +++ b/kernel/dma/debug.c @@ -706,7 +706,7 @@ static struct dma_debug_entry *dma_entry_alloc(void) #ifdef CONFIG_STACKTRACE entry->stacktrace.max_entries = DMA_DEBUG_STACKTRACE_ENTRIES; entry->stacktrace.entries = entry->st_entries; - entry->stacktrace.skip = 2; + entry->stacktrace.skip = 1; save_stack_trace(&entry->stacktrace); #endif -- 1.8.3.1