From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A3B3D49D5BF for ; Thu, 24 Sep 2026 14:58:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.70 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790261913; cv=none; b=qKCf91zj85/M4RvLslomVH+MNTN7XYotiKzBeDtHiEzhbycC6v6LLOtD/FN3qW+PZt+eD/RMzEjgmxY1XCG2KjROhWda19e+wJdcNsuDvDVJxr9Q+AMNGp+7lrXM3A3B8SBQhbJEhbx455QIsl66HYWuBqpMiNfO5g7Otr5Shoc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790261913; c=relaxed/simple; bh=iGxObYsxfMXVS4DwNX66BB2uJBMvQFGo72urG75z4Kc=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=MGQl8FE+lQLGpbU0fLWmFj/RYus7ACGiCgf5yAl2MqL2dVo/BN7e/DtTMy/3LI8wbqek246ACZg+MZiItrQDzMsh8xXZ5hG6mwjldGHPpzzfjSpkSYTgLcxZ7mzJIYZQoyeTLXcWluDU9MzMS+xc9XYJT1TdznZxHenqH3JYTzA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=YiINUp4o; arc=none smtp.client-ip=209.85.221.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="YiINUp4o" Received: by mail-wr1-f70.google.com with SMTP id ffacd0b85a97d-48701401090so1906524f8f.3 for ; Thu, 24 Sep 2026 07:58:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1790261904; x=1790866704; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:mime-version:date:from :to:cc:subject:date:message-id:reply-to:content-type; bh=1e18QunqfVE00zml0hGARGcOCLbgPTTNUS9PK9RCQ6c=; b=YiINUp4oOTBbiqrGDlgQzk6IUAQC9vYtV9S/k5DXq0U/OBR7LEmOEB+EPloGbprPeX zSh8LQdVVse7zJD5Z5u0UVQcmCG2E0426/pWtNxbWexkMOI+yqfloi6GkoE4btnW98Fa zrmBEKA4orZcXxKRhWsP8w1D31wzc7utFCwX0vNj6Z//up7Q1XLxjd44na6hd/Ph8jJa YsfoOwrzub2MsptsN+T50ozWzDYiLTsOjnQ7Y1zk6b03SRcSATyASw0dl67DuMQ9/gpM e5vUOqpcz4f7vQ1qBSSDeYkZ4J6svq/p+6IAJ5wx0GqbNDEsEXlxbcItxEQ//KZmhpu0 R+vg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1790261904; x=1790866704; h=content-type:cc:to:from:subject:message-id:mime-version:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=1e18QunqfVE00zml0hGARGcOCLbgPTTNUS9PK9RCQ6c=; b=SxvPGuzFSrSUTuDy0hVa0S2uJgpcNibxyV/SOGyT8+kfgpvWU4ExIM7J9Y7dErf8+E rKPutQL1END+knryNHdKU+dbNeBOZNXsaI+yhVZL2IzI72kJzJHmHcZK7J+o3SXyhGnY P5IJ37H/kWRyteRYnYqo8QCSd1dwAsS3Xf0kSSQqAU98GdYGX2fjfuoRPVkflEW4gPb9 eNAWpbgaMzM8epPzOimj/xixwyICYSKN1LanIPUz04xos9KPb7hDvnxiiSnwhhUWZ34s AZIgxcuhFdWd3R1iDkwAX6KKUlDsl44jGDN6mXWg0PqwWsqgvuw3q3OWP75/dCowGRYj laKA== X-Forwarded-Encrypted: i=1; AKwUvByJr8w+Ghbuhu7yMeiXeDxSTvTyNEfl4tZc1JD+3mHaUjbKrTVtXxAFpOxbQ361XEXUZRtPIDMb70fl+/0=@vger.kernel.org X-Gm-Message-State: AFuF++lQ9goOgvC/s4WTzPI2AuvXy1xfvGaytfIJ0yJ8JiLUEb8hhJX/ QeIEM8oAorBrbVIQv+9j31EwqzU0lXgvNYXBahqCnO+iW7nJ3mOEJIRJ0UWskgZz3xs3JrRGKQF lPJlT1u3QOG++EJL/DvlIcA== X-Received: from wrbep7.prod.google.com ([2002:a05:6000:42c7:b0:487:1add:cc9e]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6000:3105:b0:487:27f9:82d with SMTP id ffacd0b85a97d-488716f7577mr5418365f8f.34.1790261903929; Thu, 24 Sep 2026 07:58:23 -0700 (PDT) Date: Thu, 24 Sep 2026 15:57:34 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.56.0.rc1.310.g51773c2048-goog Message-ID: <20260924145754.1285146-1-vdonnefort@google.com> Subject: [PATCH v7 00/20] tracing/remotes: Add printk, dump_on_panic and boot parameters From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" This series extends the recently introduced trace remotes infrastructure, bringing useful features for developers: * dump_on_panic: Dump the trace remote buffer on system panic. * dmesg: Redirect remote events to dmesg. * trace_remote=: Configure a trace_remote from the commandline. * poll_ms: Modify the polling period. It also brings a couple of optimisations: * In-header compressed length support for small events. * Single work thread for remote polling. And some misc improvements: * Use kstrtobool where possible * Free resources on remote registration failure Changelog: v7: * Check for printk timestamps in dmesg selftest. (Sashiko) * Touch NMI watchdog in the panic dump loop. (Sashiko) * Add READ_ONCE()/WRITE_ONCE() for panic_on. (Sashiko) * Defer dmesg and tracing enabling after all cmdline options are parsed. (Sashiko) * Guard sysrq panic trigger in dump_on_panic.tc with TRIGGER_PANIC env variable. (Sashiko) * Rebase on 7.3-rc4 v6 (https://lore.kernel.org/all/20260817135517.3919534-1-vdonnefort@google.com/): * Replace WARN_ON with pr_warn for buf_size in cmdline parsing. (Sashiko) * Add READ_ONCE()/WRITE_ONCE() for poll_ms (Sashiko) * Add support for HAVE_64BIT_ALIGNED_ACCESS arch is set in simple_ring_buffer. (Sashiko) * Add selftest tracefs file requirements, TMPDIR leak, and awk regex. (Sashiko) * Rebase on 7.2 v5 (https://lore.kernel.org/all/20260812161340.2417322-1-vdonnefort@google.com/): * Use seq_buf_str() for safe, properly terminated trace_seq extraction. (Steven) * Remove destructive dmesg -c from selftests and rely on timestamp matching instead. (Steven) * Allow several trace_remote=XXX cmdline options. * Rebase on 7.2-rc7 v4 (https://lore.kernel.org/all/20260804140333.797210-1-vdonnefort@google.com/): * Rebase on 7.2-rc6 * Use trace_append_boot_param() to parse cmdline options. * Fix trace_remote_iterator cleanup order for non-consuming iterators (Sashiko). v3 (https://lore.kernel.org/all/20260721103603.342266-1-vdonnefort@google.com/): * Make sure dmesg and panic handlers are using null-terminated trace_seq. * Make struct trace_remote more compact * Fix dump_on_panic test unloaded case (Sashiko) * Rebase on 7.2-rc4 v2 (https://lore.kernel.org/all/20260605163825.1762953-1-vdonnefort@google.com/): Sashiko had a few spot-on comments on the v1 which forced me to heavily re-arrange the series, so I thought it'd be alright to send a v2 already including those changes. * dump_on_oops -> dump_on_panic * printk -> dmesg * Allow to configure poll_ms * Make the ring_buffer_iter functions panic-friendly * Gate tracefs .open on remote registration (Sashiko) * Use irqsave for reader lock (Sashiko) * Fix iter locking for TRI_DMESG (Sashiko) * Yield in the dmesg work (Sashiko) v1 (https://lore.kernel.org/all/20260602171146.2238998-1-vdonnefort@google.com/) Vincent Donnefort (20): tracing/remotes: Gate tracefs files opening on trace remote registration tracing/remotes: Release tracefs,eventfs on registration failure tracing/remotes: Use kstrtobool for boolean tracefs files tracing/remotes: Initialise pos in trace_start() tracing/remotes: Annotate remote shared fields with READ_ONCE/WRITE_ONCE tracing/remotes: Use a single per-remote polling work tracing/simple_ring_buffer: Add support for compressed length tracing/remotes: Add dmesg tracefs file tracing/remotes: selftests: Add a test for the dmesg tracefs file tracing/remotes: selftests: Prefix hypervisor folder ring-buffer: Use irqsave for the reader lock in ring_buffer_poll_remote ring-buffer: Use panic-friendly locking in ring_buffer_iter interface ring-buffer: Add ring_buffer_read_remote_meta_page() ring-buffer: Add kerneldoc for ring_buffer_poll_remote tracing/remotes: Add dump_on_panic tracefs file tracing/remotes: selftests: Add a test for the dump_on_panic tracefs file tracing/remotes: Add poll_ms tracefs file tracing/remotes: Add trace_remote cmdline options Documentation: tracing/remotes: Add detailed tracefs layout Documentation/kernel-parameters: Add trace_remote .../admin-guide/kernel-parameters.txt | 19 + Documentation/trace/remotes.rst | 66 +- include/linux/ring_buffer.h | 1 + kernel/trace/ring_buffer.c | 88 +- kernel/trace/simple_ring_buffer.c | 23 +- kernel/trace/trace_remote.c | 841 +++++++++++++++--- .../buffer_size.tc | 0 .../test.d/remotes/00hypervisor/dmesg.tc | 11 + .../remotes/00hypervisor/dump_on_panic.tc | 11 + .../{hypervisor => 00hypervisor}/hotplug.tc | 0 .../{hypervisor => 00hypervisor}/reset.tc | 0 .../{hypervisor => 00hypervisor}/trace.tc | 0 .../trace_pipe.tc | 0 .../{hypervisor => 00hypervisor}/unloading.tc | 0 .../selftests/ftrace/test.d/remotes/dmesg.tc | 86 ++ .../ftrace/test.d/remotes/dump_on_panic.tc | 50 ++ .../selftests/ftrace/test.d/remotes/functions | 2 + 17 files changed, 1050 insertions(+), 148 deletions(-) rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/buffer_size.tc (100%) create mode 100644 tools/testing/selftests/ftrace/test.d/remotes/00hypervisor/dmesg.tc create mode 100644 tools/testing/selftests/ftrace/test.d/remotes/00hypervisor/dump_on_panic.tc rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/hotplug.tc (100%) rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/reset.tc (100%) rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/trace.tc (100%) rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/trace_pipe.tc (100%) rename tools/testing/selftests/ftrace/test.d/remotes/{hypervisor => 00hypervisor}/unloading.tc (100%) create mode 100644 tools/testing/selftests/ftrace/test.d/remotes/dmesg.tc create mode 100644 tools/testing/selftests/ftrace/test.d/remotes/dump_on_panic.tc base-commit: 93f51579e7df248780214094418f205253383cc5 -- 2.56.0.rc1.310.g51773c2048-goog