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[2620:137:e000::3:7]) by mx.google.com with ESMTPS id i2-20020a654842000000b005c67029a131si9763808pgs.220.2023.12.13.10.22.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Dec 2023 10:22:09 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by snail.vger.email (Postfix) with ESMTP id 163A980A8B47; Wed, 13 Dec 2023 10:21:25 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235450AbjLMSVJ (ORCPT + 99 others); Wed, 13 Dec 2023 13:21:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235511AbjLMSUg (ORCPT ); Wed, 13 Dec 2023 13:20:36 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79E27D5 for ; Wed, 13 Dec 2023 10:20:39 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2797BC43391; Wed, 13 Dec 2023 18:20:39 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1rDTrI-00000002a9n-252N; Wed, 13 Dec 2023 13:21:24 -0500 Message-ID: <20231213182124.270751060@goodmis.org> User-Agent: quilt/0.67 Date: Wed, 13 Dec 2023 13:17:45 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Tzvetomir Stoyanov , Vincent Donnefort , Kent Overstreet Subject: [PATCH v3 08/15] ring-buffer: Make sure the spare sub buffer used for reads has same size References: <20231213181737.791847466@goodmis.org> MIME-Version: 1.0 X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Wed, 13 Dec 2023 10:21:25 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1785191967721830361 X-GMAIL-MSGID: 1785191967721830361 From: "Steven Rostedt (Google)" Now that the ring buffer specifies the size of its sub buffers, they all need to be the same size. When doing a read, a swap is done with a spare page. Make sure they are the same size before doing the swap, otherwise the read will fail. Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2e201ef5b1ce..dd7669f6503b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -7576,6 +7576,7 @@ struct ftrace_buffer_info { struct trace_iterator iter; void *spare; unsigned int spare_cpu; + unsigned int spare_size; unsigned int read; }; @@ -8295,6 +8296,15 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, page_size = ring_buffer_subbuf_size_get(iter->array_buffer->buffer); + /* Make sure the spare matches the current sub buffer size */ + if (info->spare) { + if (page_size != info->spare_size) { + ring_buffer_free_read_page(iter->array_buffer->buffer, + info->spare_cpu, info->spare); + info->spare = NULL; + } + } + if (!info->spare) { info->spare = ring_buffer_alloc_read_page(iter->array_buffer->buffer, iter->cpu_file); @@ -8303,6 +8313,7 @@ tracing_buffers_read(struct file *filp, char __user *ubuf, info->spare = NULL; } else { info->spare_cpu = iter->cpu_file; + info->spare_size = page_size; } } if (!info->spare)