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=-9.5 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 67134C32751 for ; Wed, 31 Jul 2019 06:24:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3BB40206A3 for ; Wed, 31 Jul 2019 06:24:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="InbuIdvw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727404AbfGaGYn (ORCPT ); Wed, 31 Jul 2019 02:24:43 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:36477 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727303AbfGaGYn (ORCPT ); Wed, 31 Jul 2019 02:24:43 -0400 Received: by mail-pl1-f195.google.com with SMTP id k8so30030614plt.3 for ; Tue, 30 Jul 2019 23:24:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=qPNDXgZPeD/yc67o95C8RuRDptaWT4TdPlrwZmzPvAk=; b=InbuIdvwP3Y4gywzK0Nf+ECkQVeMzVN3Sv0btkVQFK76yx4gxApm3XQaG3b8xnC+mv VdbRiNEOCdmiQVWEI+5/wQ+vJfgfJFc0QvctI70OhP8jETrKN/Dk/+Y5XCFavYlmmzzF obmNJY6nOr29lkInsWfdKDWYfrSidiyAXs2JlhdwJnuSRyvtHYT1g6ps7PD+UrFhZb4a w932/xzIvt4PQVaSYiDrm2/c8WWNT6/Z54mz/kPKTyQLi+TdLrFZf+KuSb5QCgIUutUW BkHryJsBJE4/si7kvVsyK409c/7VnlAi3AuSf84+Xi06x8HHhqkXubZ9eSTZvtjpYNoz 3gyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=qPNDXgZPeD/yc67o95C8RuRDptaWT4TdPlrwZmzPvAk=; b=Jpp6/5ac13LUOY8pPGxVqDCe4Uo+jbO7bqOnv5eOOvJUqwGhHomNEVftoucUDDjKN8 Uy/srQeMDyBoMOGhD7iahHDhzdX9bYzE5SWtnCUsMgzEA6ZpkcIh1TLipgfLTw4j/k65 k0QkFJcliD6f+TkvPFlyNCipULxuzZl8oa9vzpgmg3rFdTy5sHviXUpd3PyDodWMebzI BoBdzMYG6zymKMJ36IJmF9daVNxo6yzL+X8hExtB9znfqJGI4XOmgizma4Tkq5dv0n21 CUiDliw3kS0ugNxCRHBD6r6mxQF+zeYoNWycC0UmFxNpO7kTTnRnJy8ECw1Zxp4c1tww EZMQ== X-Gm-Message-State: APjAAAW9DAiW2GpJ9zLX7VlMkYPkDT0uXogkQMYTeNlxmVMODgN9qU8g BqCBLoBcyaH6UjEQNrOzmOM= X-Google-Smtp-Source: APXvYqzDwdOaw51aou0XSnvwMPV94XYKJT1ktYDuiPl4gKkVyLYHDIMgCkcdcKASoo3qADpbxc7ZYA== X-Received: by 2002:a17:902:7407:: with SMTP id g7mr120158084pll.214.1564554282501; Tue, 30 Jul 2019 23:24:42 -0700 (PDT) Received: from hfq-skylake.ipads-lab.se.sjtu.edu.cn ([202.120.40.82]) by smtp.googlemail.com with ESMTPSA id 11sm67552871pfw.33.2019.07.30.23.24.39 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 30 Jul 2019 23:24:42 -0700 (PDT) From: Fuqian Huang Cc: Maarten Lankhorst , Maxime Ripard , Sean Paul , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Fuqian Huang Subject: [PATCH v2] drm: use trace_printk rather than printk in drm_dbg. Date: Wed, 31 Jul 2019 14:24:16 +0800 Message-Id: <20190731062416.26238-1-huangfq.daxian@gmail.com> X-Mailer: git-send-email 2.11.0 To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In drivers/gpu/drm/amd/amdgpu/amdgpu_ih.c, amdgpu_ih_process calls DRM_DEBUG which calls drm_dbg and finally calls printk. As amdgpu_ih_process is called from an interrupt handler, and interrupt handler should be short as possible. As printk may lead to bogging down the system or can even create a live lock. printk should not be used in IRQ context. Instead, trace_printk is recommended in IRQ context. Link: https://lwn.net/Articles/365835 Reviewed-by: Joe Perches Signed-off-by: Fuqian Huang --- Changes in v2: - Only make the interrupt uses the trace_printk to avoid all 4000+ drm_dbg/DRM_DEBUG uses emitting a trace_printk. drivers/gpu/drm/drm_print.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c index a17c8a14dba4..747835d16fa6 100644 --- a/drivers/gpu/drm/drm_print.c +++ b/drivers/gpu/drm/drm_print.c @@ -236,9 +236,13 @@ void drm_dbg(unsigned int category, const char *format, ...) vaf.fmt = format; vaf.va = &args; - printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", - __builtin_return_address(0), &vaf); - + if (in_interrupt()) { + trace_printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", + __builtin_return_address(0), &vaf); + } else { + printk(KERN_DEBUG "[" DRM_NAME ":%ps] %pV", + __builtin_return_address(0), &vaf); + } va_end(args); } EXPORT_SYMBOL(drm_dbg); -- 2.11.0