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[23.128.96.37]) by mx.google.com with ESMTPS id f5-20020a17090ace0500b0028644ca706dsi5398190pju.171.2023.12.09.20.05.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 09 Dec 2023 20:05:03 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 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 A2D37805F0A5; Sat, 9 Dec 2023 20:05:02 -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 S231522AbjLJEEo (ORCPT + 99 others); Sat, 9 Dec 2023 23:04:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231496AbjLJEEI (ORCPT ); Sat, 9 Dec 2023 23:04:08 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 855FC118 for ; Sat, 9 Dec 2023 20:04:14 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B427C433B7; Sun, 10 Dec 2023 04:04:14 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1rCB3j-000000021Pm-0Gbc; Sat, 09 Dec 2023 23:04:51 -0500 Message-ID: <20231210040450.846348590@goodmis.org> User-Agent: quilt/0.67 Date: Sat, 09 Dec 2023 22:54:13 -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 09/14] tracing: Update snapshot order along with main buffer order References: <20231210035404.053677508@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]); Sat, 09 Dec 2023 20:05:02 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1784866253095908953 X-GMAIL-MSGID: 1784866253095908953 From: "Steven Rostedt (Google)" When updating the order of the sub buffers for the main buffer, make sure that if the snapshot buffer exists, that it gets its order updated as well. Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 45 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 43 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b3b36d7f1201..7faaaf29b504 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1263,10 +1263,17 @@ static void set_buffer_entries(struct array_buffer *buf, unsigned long val); int tracing_alloc_snapshot_instance(struct trace_array *tr) { + int order; int ret; if (!tr->allocated_snapshot) { + /* Make the snapshot buffer have the same order as main buffer */ + order = ring_buffer_subbuf_order_get(tr->array_buffer.buffer); + ret = ring_buffer_subbuf_order_set(tr->max_buffer.buffer, order); + if (ret < 0) + return ret; + /* allocate spare buffer */ ret = resize_buffer_duplicate_size(&tr->max_buffer, &tr->array_buffer, RING_BUFFER_ALL_CPUS); @@ -1286,6 +1293,7 @@ static void free_snapshot(struct trace_array *tr) * The max_tr ring buffer has some state (e.g. ring->clock) and * we want preserve it. */ + ring_buffer_subbuf_order_set(tr->max_buffer.buffer, 0); ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS); set_buffer_entries(&tr->max_buffer, 1); tracing_reset_online_cpus(&tr->max_buffer); @@ -9378,6 +9386,7 @@ buffer_order_write(struct file *filp, const char __user *ubuf, { struct trace_array *tr = filp->private_data; unsigned long val; + int old_order; int ret; ret = kstrtoul_from_user(ubuf, cnt, 10, &val); @@ -9388,12 +9397,44 @@ buffer_order_write(struct file *filp, const char __user *ubuf, if (val < 0 || val > 7) return -EINVAL; + old_order = ring_buffer_subbuf_order_get(tr->array_buffer.buffer); + if (old_order == val) + return 0; + ret = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, val); if (ret) - return ret; + return 0; - (*ppos)++; +#ifdef CONFIG_TRACER_MAX_TRACE + if (!tr->allocated_snapshot) + goto out_max; + + ret = ring_buffer_subbuf_order_set(tr->max_buffer.buffer, val); + if (ret) { + /* Put back the old order */ + cnt = ring_buffer_subbuf_order_set(tr->array_buffer.buffer, old_order); + if (WARN_ON_ONCE(cnt)) { + /* + * AARGH! We are left with different orders! + * The max buffer is our "snapshot" buffer. + * When a tracer needs a snapshot (one of the + * latency tracers), it swaps the max buffer + * with the saved snap shot. We succeeded to + * update the order of the main buffer, but failed to + * update the order of the max buffer. But when we tried + * to reset the main buffer to the original size, we + * failed there too. This is very unlikely to + * happen, but if it does, warn and kill all + * tracing. + */ + tracing_disabled = 1; + } + return ret; + } + out_max: +#endif + (*ppos)++; return cnt; }