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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 EF044C433E1 for ; Thu, 20 Aug 2020 12:39:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C0E9F207DA for ; Thu, 20 Aug 2020 12:39:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597927172; bh=bHJHwNmJXUROGFe8pMHB6dazDbjUUBkWXzGhIAmLMSI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NGVHNyV6n5a031HEVYBHWlUDp8mFggIRAdyQHuM5qhqtg7udZfSlNcSfEjg/fRRJ2 DCxOO6p4VOpXq+Ez8nN56VcTRb3hFqmOf5PlJhGDfzWljfHp/rpHdiW6ufr+iVHPDf I9XfhR/2YPp7X0v0dhSiQH3tJpulElEue0Z2GJ3A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729451AbgHTMjb (ORCPT ); Thu, 20 Aug 2020 08:39:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:50386 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729395AbgHTJrH (ORCPT ); Thu, 20 Aug 2020 05:47:07 -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 8D9BA22B43; Thu, 20 Aug 2020 09:47:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597916827; bh=bHJHwNmJXUROGFe8pMHB6dazDbjUUBkWXzGhIAmLMSI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ueqXuxmXWENoEUD/P4vioIfyPyKAbfUZkAj/ndZuqlOM91xp3zF3WUefkEE7bLhfz 3MVFczUHwNpzi08X5c4GX9kLLe1LnYRs7BttOlv4nvMpoLGvLSNNZpNIGjmNrw9Gx8 MaDqm0uZeL4uqkHggvVKQIPic4XcoQIgLgxQQBZE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Steven Rostedt (VMware)" , dann frazier Subject: [PATCH 5.4 061/152] tracing: Move pipe reference to trace array instead of current_tracer Date: Thu, 20 Aug 2020 11:20:28 +0200 Message-Id: <20200820091556.846156608@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200820091553.615456912@linuxfoundation.org> References: <20200820091553.615456912@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt (VMware) commit 7ef282e05132d56b6f6b71e3873f317664bea78b upstream. 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) [Resolved conflict in __remove_instance()] Signed-off-by: dann frazier Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 12 ++++++------ kernel/trace/trace.h | 2 +- 2 files changed, 7 insertions(+), 7 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5686,7 +5686,7 @@ static int tracing_set_tracer(struct tra } /* 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; } @@ -5902,7 +5902,7 @@ static int tracing_open_pipe(struct inod nonseekable_open(inode, filp); - tr->current_trace->ref++; + tr->trace_ref++; out: mutex_unlock(&trace_types_lock); return ret; @@ -5921,7 +5921,7 @@ static int tracing_release_pipe(struct i mutex_lock(&trace_types_lock); - tr->current_trace->ref--; + tr->trace_ref--; if (iter->trace->pipe_close) iter->trace->pipe_close(iter); @@ -7230,7 +7230,7 @@ static int tracing_buffers_open(struct i filp->private_data = info; - tr->current_trace->ref++; + tr->trace_ref++; mutex_unlock(&trace_types_lock); @@ -7331,7 +7331,7 @@ static int tracing_buffers_release(struc mutex_lock(&trace_types_lock); - iter->tr->current_trace->ref--; + iter->tr->trace_ref--; __trace_array_put(iter->tr); @@ -8470,7 +8470,7 @@ static int __remove_instance(struct trac { int i; - if (tr->ref || (tr->current_trace && tr->current_trace->ref)) + if (tr->ref || (tr->current_trace && tr->trace_ref)) return -EBUSY; list_del(&tr->list); --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -309,6 +309,7 @@ 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; @@ -498,7 +499,6 @@ struct tracer { struct tracer *next; struct tracer_flags *flags; int enabled; - int ref; bool print_max; bool allow_instances; #ifdef CONFIG_TRACER_MAX_TRACE