From patchwork Fri Sep 4 06:09:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gaurav Kohli X-Patchwork-Id: 250405 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=-13.0 required=3.0 tests=BAYES_00, 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 0D0C1C43461 for ; Fri, 4 Sep 2020 06:10:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1C83206E7 for ; Fri, 4 Sep 2020 06:10:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726114AbgIDGKM (ORCPT ); Fri, 4 Sep 2020 02:10:12 -0400 Received: from alexa-out.qualcomm.com ([129.46.98.28]:12054 "EHLO alexa-out.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725892AbgIDGKL (ORCPT ); Fri, 4 Sep 2020 02:10:11 -0400 Received: from ironmsg08-lv.qualcomm.com ([10.47.202.152]) by alexa-out.qualcomm.com with ESMTP; 03 Sep 2020 23:10:10 -0700 Received: from ironmsg02-blr.qualcomm.com ([10.86.208.131]) by ironmsg08-lv.qualcomm.com with ESMTP/TLS/AES256-SHA; 03 Sep 2020 23:10:08 -0700 Received: from gkohli-linux.qualcomm.com ([10.204.78.26]) by ironmsg02-blr.qualcomm.com with ESMTP; 04 Sep 2020 11:40:00 +0530 Received: by gkohli-linux.qualcomm.com (Postfix, from userid 427023) id 8A20421265; Fri, 4 Sep 2020 11:39:58 +0530 (IST) From: Gaurav Kohli To: rostedt@goodmis.org, mingo@redhat.com Cc: linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Gaurav Kohli Subject: [PATCH] trace: Fix race in trace_open and buffer resize call Date: Fri, 4 Sep 2020 11:39:57 +0530 Message-Id: <1599199797-25978-1-git-send-email-gkohli@codeaurora.org> X-Mailer: git-send-email 2.7.4 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Below race can come, if trace_open and resize of cpu buffer is running parallely on different cpus CPUX CPUY ring_buffer_resize atomic_read(&buffer->resize_disabled) tracing_open tracing_reset_online_cpus ring_buffer_reset_cpu rb_reset_cpu rb_update_pages remove/insert pages resetting pointer This race can cause data abort or some times infinte loop in rb_remove_pages and rb_insert_pages while checking pages for sanity. Take ring buffer lock in trace_open to avoid resetting of cpu buffer. Signed-off-by: Gaurav Kohli diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 136ea09..55f9115 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -163,6 +163,8 @@ bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu); void ring_buffer_record_disable(struct trace_buffer *buffer); void ring_buffer_record_enable(struct trace_buffer *buffer); +void ring_buffer_mutex_acquire(struct trace_buffer *buffer); +void ring_buffer_mutex_release(struct trace_buffer *buffer); void ring_buffer_record_off(struct trace_buffer *buffer); void ring_buffer_record_on(struct trace_buffer *buffer); bool ring_buffer_record_is_on(struct trace_buffer *buffer); diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 93ef0ab..638ec8f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3632,6 +3632,25 @@ void ring_buffer_record_enable(struct trace_buffer *buffer) EXPORT_SYMBOL_GPL(ring_buffer_record_enable); /** + * ring_buffer_mutex_acquire - prevent resetting of buffer + * during resize + */ +void ring_buffer_mutex_acquire(struct trace_buffer *buffer) +{ + mutex_lock(&buffer->mutex); +} +EXPORT_SYMBOL_GPL(ring_buffer_mutex_acquire); + +/** + * ring_buffer_mutex_release - prevent resetting of buffer + * during resize + */ +void ring_buffer_mutex_release(struct trace_buffer *buffer) +{ + mutex_unlock(&buffer->mutex); +} +EXPORT_SYMBOL_GPL(ring_buffer_mutex_release); +/** * ring_buffer_record_off - stop all writes into the buffer * @buffer: The ring buffer to stop writes to. * @@ -4918,6 +4937,8 @@ void ring_buffer_reset(struct trace_buffer *buffer) struct ring_buffer_per_cpu *cpu_buffer; int cpu; + /* prevent another thread from changing buffer sizes */ + mutex_lock(&buffer->mutex); for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; @@ -4936,6 +4957,7 @@ void ring_buffer_reset(struct trace_buffer *buffer) atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled); } + mutex_unlock(&buffer->mutex); } EXPORT_SYMBOL_GPL(ring_buffer_reset); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index f40d850..392e9aa 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2006,6 +2006,8 @@ void tracing_reset_online_cpus(struct array_buffer *buf) if (!buffer) return; + ring_buffer_mutex_acquire(buffer); + ring_buffer_record_disable(buffer); /* Make sure all commits have finished */ @@ -2016,6 +2018,8 @@ void tracing_reset_online_cpus(struct array_buffer *buf) ring_buffer_reset_online_cpus(buffer); ring_buffer_record_enable(buffer); + + ring_buffer_mutex_release(buffer); } /* Must have trace_types_lock held */