From patchwork Mon Aug 17 15:12:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 266503 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, 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 D78A0C433DF for ; Mon, 17 Aug 2020 15:28:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C694F23B16 for ; Mon, 17 Aug 2020 15:28:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597678124; bh=pHYlclpSKjbiZNMgPJarljjkUereLNLSMpnfdT7p3Ow=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=efcULtrf7yNjTVK08prd7EwPCpJJQARyGTxvxM1Y/M5TF/4Yem+TMhjmFZRtoxfd4 56Fz8vntMrtogdnlxw75FhEUx7O9iNaAdDvIwZgEXy+6JA+Cc1un+avVEHZgH2r1m4 hBAhe8fX0URRjF2joZm3cr/pa5PuxWdCyB7WrChM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729421AbgHQP2k (ORCPT ); Mon, 17 Aug 2020 11:28:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:43422 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730016AbgHQP2c (ORCPT ); Mon, 17 Aug 2020 11:28:32 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DBE7923BDB; Mon, 17 Aug 2020 15:28:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597678109; bh=pHYlclpSKjbiZNMgPJarljjkUereLNLSMpnfdT7p3Ow=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LUD/XY0/MBiralYET8YUBUsO3PY9+eWkSSvAOxNtEmMdmH0iLTQyzwjJkdRXuQCuI +ijFHEhFLMJXPmUa3zR76Yb3JhO9ovVItlGVWejxT63ScC4l4xJBXjv4oFaSNJuOhv pwrhgeoHSn88P+wSG9ePxwJWpIbRmI8lM5cwoJEg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Steven Rostedt (VMware)" , Sasha Levin Subject: [PATCH 5.8 191/464] tracing: Move pipe reference to trace array instead of current_tracer Date: Mon, 17 Aug 2020 17:12:24 +0200 Message-Id: <20200817143842.971050640@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200817143833.737102804@linuxfoundation.org> References: <20200817143833.737102804@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Steven Rostedt (VMware) [ Upstream commit 7ef282e05132d56b6f6b71e3873f317664bea78b ] If a process has the trace_pipe open on a trace_array, the current tracer for that trace array should not be changed. This was original enforced by a global lock, but when instances were introduced, it was moved to the current_trace. But this structure is shared by all instances, and a trace_pipe is for a single instance. There's no reason that a process that has trace_pipe open on one instance should prevent another instance from changing its current tracer. Move the reference counter to the trace_array instead. This is marked as "Fixes" but is more of a clean up than a true fix. Backport if you want, but its not critical. Fixes: cf6ab6d9143b1 ("tracing: Add ref count to tracer for when they are being read by pipe") Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/trace/trace.c | 12 ++++++------ kernel/trace/trace.h | 2 +- 2 files changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index bb62269724d5f..6fc6da55b94e2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5887,7 +5887,7 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) } /* If trace pipe files are being read, we can't change the tracer */ - if (tr->current_trace->ref) { + if (tr->trace_ref) { ret = -EBUSY; goto out; } @@ -6103,7 +6103,7 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp) nonseekable_open(inode, filp); - tr->current_trace->ref++; + tr->trace_ref++; out: mutex_unlock(&trace_types_lock); return ret; @@ -6122,7 +6122,7 @@ static int tracing_release_pipe(struct inode *inode, struct file *file) mutex_lock(&trace_types_lock); - tr->current_trace->ref--; + tr->trace_ref--; if (iter->trace->pipe_close) iter->trace->pipe_close(iter); @@ -7424,7 +7424,7 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp) filp->private_data = info; - tr->current_trace->ref++; + tr->trace_ref++; mutex_unlock(&trace_types_lock); @@ -7525,7 +7525,7 @@ static int tracing_buffers_release(struct inode *inode, struct file *file) mutex_lock(&trace_types_lock); - iter->tr->current_trace->ref--; + iter->tr->trace_ref--; __trace_array_put(iter->tr); @@ -8733,7 +8733,7 @@ static int __remove_instance(struct trace_array *tr) int i; /* Reference counter for a newly created trace array = 1. */ - if (tr->ref > 1 || (tr->current_trace && tr->current_trace->ref)) + if (tr->ref > 1 || (tr->current_trace && tr->trace_ref)) return -EBUSY; list_del(&tr->list); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 13db4000af3fe..f21607f871891 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -356,6 +356,7 @@ struct trace_array { struct trace_event_file *trace_marker_file; cpumask_var_t tracing_cpumask; /* only trace on set CPUs */ int ref; + int trace_ref; #ifdef CONFIG_FUNCTION_TRACER struct ftrace_ops *ops; struct trace_pid_list __rcu *function_pids; @@ -547,7 +548,6 @@ struct tracer { struct tracer *next; struct tracer_flags *flags; int enabled; - int ref; bool print_max; bool allow_instances; #ifdef CONFIG_TRACER_MAX_TRACE