From patchwork Fri Aug 5 21:53:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jim Cromie X-Patchwork-Id: 595556 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 E8D04C25B08 for ; Fri, 5 Aug 2022 21:54:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241544AbiHEVyV (ORCPT ); Fri, 5 Aug 2022 17:54:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241497AbiHEVyN (ORCPT ); Fri, 5 Aug 2022 17:54:13 -0400 Received: from mail-io1-xd2d.google.com (mail-io1-xd2d.google.com [IPv6:2607:f8b0:4864:20::d2d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BA4DEC43; Fri, 5 Aug 2022 14:54:11 -0700 (PDT) Received: by mail-io1-xd2d.google.com with SMTP id p82so2864379iod.2; Fri, 05 Aug 2022 14:54:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc; bh=8o46kS926x+QNuy5c4uBrvlsDlM/ABLoibmgwB6shD8=; b=lCM46axrhDjSPX2DcnzhMibG89Bub0Ejuetk3i4ZBIR4SKCTxg15/vbM+20ToloihC 5jJiPEBFpAYYsXVKLemc1F/6Fml/cnNqToitEQ7LP7jGmZGwrFUe80YvURLB4CE8UFmL 0T6/KfGyyq2L+pxXcJk/NFZVoOy4bAeINZaSVm+k6eQyztxe6FxW6QSllYUcNAHv8hoU O9yQgZtxinxHzbgXYMwmvu/KTIro5W39ChI58qjUIfAeJtBrt69zS23Cb+HdPV1ZWhnc JaZbhuEPr4rm39f9bibgDkng3eX1JX7n13q9Zu9wfECZ4hf7vy6yT71yq+UNFpTwV50w JpCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc; bh=8o46kS926x+QNuy5c4uBrvlsDlM/ABLoibmgwB6shD8=; b=RrM/Y9vzZj2q/VewZK2pkV3klo3Yfzmw8L/Nc592QKjXxmoYxXzo9sGe+TINi9YLd/ D4nj/JhWPytOYzOxepDtibhTI0BFyu0HfASrX2lfo6c3dFu9k8DZ95O9yO/g4R3suLmK NSDsaKlHGUYfcxRi2mpNgWIf/yL+gAljLuzzPUmgJMGqADoIYuUE90xK8koDuD9yAidz GUqOKNDFLnUsugD7/F7qViPIM1otJ0JGGtsPm3259blLFilZchX1F0H3BoG1263g013a pOVxoR+Jy8Brv8meGbYkTyb5oXsoT1Ys+zrCkk3ANAeNJWXLZ4FdcyTtnexX6bovmZwm IF0A== X-Gm-Message-State: ACgBeo0+k9VJlBocc0GQxRbvdFHtl5fqHx3agzfeg69LBhqEm/mgh22C fBG6W5Oot0jnPj4e4RruL0dbYQQoewx8HA== X-Google-Smtp-Source: AA6agR6i3ziM+LCX9b0EWHuhKQUsORqHbRROxpskVgxuS7LNqXf+MhlHawIxN9ifY+85v7VA3rL23g== X-Received: by 2002:a05:6638:3387:b0:33c:9f9e:5a17 with SMTP id h7-20020a056638338700b0033c9f9e5a17mr3896561jav.12.1659736450608; Fri, 05 Aug 2022 14:54:10 -0700 (PDT) Received: from frodo.. (c-73-78-62-130.hsd1.co.comcast.net. [73.78.62.130]) by smtp.googlemail.com with ESMTPSA id e12-20020a056602044c00b0067c09fd0b53sm1765532iov.21.2022.08.05.14.54.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Aug 2022 14:54:10 -0700 (PDT) From: Jim Cromie To: linux-kernel@vger.kernel.org, jbaron@akamai.com, gregkh@linuxfoundation.org, dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-arm-msm@vger.kernel.org Cc: daniel.vetter@ffwll.ch, seanpaul@chromium.org, robdclark@gmail.com, Jim Cromie , vincent.whitchurch@axis.com Subject: [PATCH v5 01/33] dyndbg: fix static_branch manipulation Date: Fri, 5 Aug 2022 15:53:23 -0600 Message-Id: <20220805215355.3509287-2-jim.cromie@gmail.com> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220805215355.3509287-1-jim.cromie@gmail.com> References: <20220805215355.3509287-1-jim.cromie@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org In https://lore.kernel.org/lkml/20211209150910.GA23668@axis.com/ Vincent's patch commented on, and worked around, a bug toggling static_branch's, when a 2nd PRINTK-ish flag was added. The bug results in a premature static_branch_disable when the 1st of 2 flags was disabled. The cited commit computed newflags, but then in the JUMP_LABEL block, failed to use that result, instead using just one of the terms in it. Using newflags instead made the code work properly. This is Vincents test-case, reduced. It needs the 2nd flag to demonstrate the bug, but it's explanatory here. pt_test() { echo 5 > /sys/module/dynamic_debug/verbose site="module tcp" # just one callsite echo " $site =_ " > /proc/dynamic_debug/control # clear it # A B ~A ~B for flg in +T +p "-T #broke here" -p; do echo " $site $flg " > /proc/dynamic_debug/control done; # A B ~B ~A for flg in +T +p "-p #broke here" -T; do echo " $site $flg " > /proc/dynamic_debug/control done } pt_test Fixes: 84da83a6ffc0 dyndbg: combine flags & mask into a struct, simplify with it CC: vincent.whitchurch@axis.com Signed-off-by: Jim Cromie Acked-by: Jason Baron --- .drop @stable, no exposed bug. .add jbaron ack --- lib/dynamic_debug.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index dd7f56af9aed..a56c1286ffa4 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -211,10 +211,11 @@ static int ddebug_change(const struct ddebug_query *query, continue; #ifdef CONFIG_JUMP_LABEL if (dp->flags & _DPRINTK_FLAGS_PRINT) { - if (!(modifiers->flags & _DPRINTK_FLAGS_PRINT)) + if (!(newflags & _DPRINTK_FLAGS_PRINT)) static_branch_disable(&dp->key.dd_key_true); - } else if (modifiers->flags & _DPRINTK_FLAGS_PRINT) + } else if (newflags & _DPRINTK_FLAGS_PRINT) { static_branch_enable(&dp->key.dd_key_true); + } #endif dp->flags = newflags; v4pr_info("changed %s:%d [%s]%s =%s\n",