From nobody Sun Dec 28 02:50:05 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77735C4332F for ; Wed, 13 Dec 2023 18:21:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233746AbjLMSVZ (ORCPT ); Wed, 13 Dec 2023 13:21:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44908 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1441940AbjLMSUh (ORCPT ); Wed, 13 Dec 2023 13:20:37 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 084AF136 for ; Wed, 13 Dec 2023 10:20:39 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6D686C433D9; Wed, 13 Dec 2023 18:20:39 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1rDTrI-00000002aAH-3J2I; Wed, 13 Dec 2023 13:21:24 -0500 Message-ID: <20231213182124.562137066@goodmis.org> User-Agent: quilt/0.67 Date: Wed, 13 Dec 2023 13:17:46 -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 09/15] tracing: Update snapshot order along with main buffer order References: <20231213181737.791847466@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 dd7669f6503b..658bb1f04e9c 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); =20 int tracing_alloc_snapshot_instance(struct trace_array *tr) { + int order; int ret; =20 if (!tr->allocated_snapshot) { =20 + /* Make the snapshot buffer have the same order as main buffer */ + order =3D ring_buffer_subbuf_order_get(tr->array_buffer.buffer); + ret =3D ring_buffer_subbuf_order_set(tr->max_buffer.buffer, order); + if (ret < 0) + return ret; + /* allocate spare buffer */ ret =3D 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); @@ -9387,6 +9395,7 @@ buffer_order_write(struct file *filp, const char __us= er *ubuf, { struct trace_array *tr =3D filp->private_data; unsigned long val; + int old_order; int ret; =20 ret =3D kstrtoul_from_user(ubuf, cnt, 10, &val); @@ -9397,12 +9406,44 @@ buffer_order_write(struct file *filp, const char __= user *ubuf, if (val < 0 || val > 7) return -EINVAL; =20 + old_order =3D ring_buffer_subbuf_order_get(tr->array_buffer.buffer); + if (old_order =3D=3D val) + return 0; + ret =3D ring_buffer_subbuf_order_set(tr->array_buffer.buffer, val); if (ret) - return ret; + return 0; =20 - (*ppos)++; +#ifdef CONFIG_TRACER_MAX_TRACE + + if (!tr->allocated_snapshot) + goto out_max; =20 + ret =3D ring_buffer_subbuf_order_set(tr->max_buffer.buffer, val); + if (ret) { + /* Put back the old order */ + cnt =3D 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 =3D 1; + } + return ret; + } + out_max: +#endif + (*ppos)++; return cnt; } =20 --=20 2.42.0