From nobody Thu Apr 2 17:22:48 2026 Received: from mail-wr1-f74.google.com (mail-wr1-f74.google.com [209.85.221.74]) (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 DDFE83CD8B3 for ; Mon, 9 Mar 2026 16:26:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773073569; cv=none; b=nvoYVUNNuJCg7yR6QDgOCUkhZt0lh5TEK9ZAEOFPl0c3k519x0X5XmcGi4n9f9S9jE5mvdYhhU6YiJ+X/cJQwH80TYZs+WgTiiGzJi9yvJXunaWbKZ0ro7Yn4i3mrtbbkCnO/gbZsYir7l2Aph1pasa/gbQRmkhBbF3lEEQW+jE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773073569; c=relaxed/simple; bh=CQB4OHKC6a/USHlkPZV7C6bsVAu6PnT5zM7PXiaR5YY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=kRiYgyToRWrMPmK8zOodPWpTVOWAix2iv7W9XY0A7APtveyUcAspnAekexsM0ll2hebSDSn3j3fGqFpo1gno6sEEvJwFFg2QocnvX7buptqLxu8ATcyqIMBzanZQU48aSjAeuEM6l/2sev5+pcxSADITrH66KdsvV5NRZapsi4o= 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=vhUlDHh2; arc=none smtp.client-ip=209.85.221.74 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="vhUlDHh2" Received: by mail-wr1-f74.google.com with SMTP id ffacd0b85a97d-439beddef55so6419362f8f.0 for ; Mon, 09 Mar 2026 09:26:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1773073566; x=1773678366; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=IFq1QzHqVSYqV3EhHbsp/w5T0l1q5txSHzBQrIlCqvk=; b=vhUlDHh2V+ky+6V86D8mkv/AJhibIL8p9Mdyv9y8f3Itl594KFfEf9/SLjGCvk2BYy PmNIHn3jqi7JByJFnJAYEXkTX4I76PA1xhpaNSvYp+LijgN//9tZmXuOQazcbqq/QoOn rwLzNigcBzBRGinrk+xTNPwGvBqVOsbotqnt7EcH6webqwxl+HVFsEW6j/5Z/LNb8Z31 uHsYnzIwkzwtjLp7nqXx8d5glmf/mZieT7x2CSA7dyJkiDOJv06CibclfzD51avddQkx bF3gZ5m1kSAh3lHFtUt0LjVe05/F0+YyZ6ZvhStr0VJ3Wgy9/b0OOoEBPJqiYcfFiRR4 NiVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773073566; x=1773678366; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=IFq1QzHqVSYqV3EhHbsp/w5T0l1q5txSHzBQrIlCqvk=; b=W127O/enuCrB23xlo0x5Kpitgk2rtzhnKAyGv1ftFjyp+UGLCFKs0MrcDwX3hrluaV v6KPQDHnluh3UNe+RAAFTq8LnDEatxFvI1FgOgijudFLLOVEx+wfSOT575cpF3+enY3T VnQhTdbAhy0NkRFCtarVHQW7QR8iA8fIwPGRm7/cXjMLnUGhE4O/qAX7PrXpP9HEntEn B/x2U2lY5p/+0lnEk84hig4tWSePB14fHGzwh9IcjZJPF7xBD29O/FcdT6XaRBklixfV 4bLhmX4LL3z4opC6gJzJ8n6I5v+YrRv4gSeaINy41Za5GafX1x7UqWgDOWlmtmIkd0Xq nmPw== X-Forwarded-Encrypted: i=1; AJvYcCW9RypWh2SYmAdMyZcmxB0sPg1ZZ7ZynfKJmxHIZ8KJGErlNWd40GcJOq/3xRC5D7pa9IzfE4Ka1fBgUcQ=@vger.kernel.org X-Gm-Message-State: AOJu0YxTXODlNxe5SLFt3STRKsMX3GlGFgVSPtX941dktvGl5JkudgXH 5LhM4g8GeW+SfUI+ZeHuwvLcTwwcT28ruBUbhGFq4RWdNnvPQDtEGeSwZeVTRbqjY7TFpffOzIk Ms+VXc0NRko7Fv0/cYmB+1A== X-Received: from wmpj41.prod.google.com ([2002:a05:600c:48a9:b0:485:3a2f:2f7e]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:64ce:b0:485:3ca4:4ef4 with SMTP id 5b1f17b1804b1-4853ca451d9mr48932985e9.9.1773073566106; Mon, 09 Mar 2026 09:26:06 -0700 (PDT) Date: Mon, 9 Mar 2026 16:24:52 +0000 In-Reply-To: <20260309162516.2623589-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260309162516.2623589-1-vdonnefort@google.com> X-Mailer: git-send-email 2.53.0.473.g4a7958ca14-goog Message-ID: <20260309162516.2623589-7-vdonnefort@google.com> Subject: [PATCH v14 06/30] tracing: Add reset to trace remotes From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, aneesh.kumar@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Allow to reset the trace remote buffer by writing to the Tracefs "trace" file. This is similar to the regular Tracefs interface. Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index 65b7e7b8267c..10ca03dc192b 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -17,6 +17,8 @@ * remote to allow writing. * @swap_reader_page: Called when Tracefs consumes a new page from a * ring-buffer. It is expected from the remote to isolate a + * @reset: Called on `echo 0 > trace`. It is expected from the + * remote to reset all ring-buffer pages. * new reader-page from the @cpu ring-buffer. */ struct trace_remote_callbacks { @@ -24,6 +26,7 @@ struct trace_remote_callbacks { void (*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv); int (*enable_tracing)(bool enable, void *priv); int (*swap_reader_page)(unsigned int cpu, void *priv); + int (*reset)(unsigned int cpu, void *priv); }; =20 int trace_remote_register(const char *name, struct trace_remote_callbacks = *cbs, void *priv); diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c index 8b06f730376e..a7b94736dd38 100644 --- a/kernel/trace/trace_remote.c +++ b/kernel/trace/trace_remote.c @@ -63,6 +63,7 @@ static int trace_remote_load(struct trace_remote *remote) rb_remote->desc =3D desc; rb_remote->swap_reader_page =3D remote->cbs->swap_reader_page; rb_remote->priv =3D remote->priv; + rb_remote->reset =3D remote->cbs->reset; remote->trace_buffer =3D ring_buffer_alloc_remote(rb_remote); if (!remote->trace_buffer) { remote->cbs->unload_trace_buffer(desc, remote->priv); @@ -138,6 +139,21 @@ static int trace_remote_disable_tracing(struct trace_r= emote *remote) return 0; } =20 +static void trace_remote_reset(struct trace_remote *remote, int cpu) +{ + lockdep_assert_held(&remote->lock); + + if (!trace_remote_loaded(remote)) + return; + + if (cpu =3D=3D RING_BUFFER_ALL_CPUS) + ring_buffer_reset(remote->trace_buffer); + else + ring_buffer_reset_cpu(remote->trace_buffer, cpu); + + trace_remote_try_unload(remote); +} + static ssize_t tracing_on_write(struct file *filp, const char __user *ubuf, size_t cnt, l= off_t *ppos) { @@ -414,6 +430,26 @@ static const struct file_operations trace_pipe_fops = =3D { .release =3D trace_pipe_release, }; =20 +static ssize_t trace_write(struct file *filp, const char __user *ubuf, siz= e_t cnt, loff_t *ppos) +{ + struct inode *inode =3D file_inode(filp); + struct trace_remote *remote =3D inode->i_private; + int cpu =3D RING_BUFFER_ALL_CPUS; + + if (inode->i_cdev) + cpu =3D (long)inode->i_cdev - 1; + + guard(mutex)(&remote->lock); + + trace_remote_reset(remote, cpu); + + return cnt; +} + +static const struct file_operations trace_fops =3D { + .write =3D trace_write, +}; + static int trace_remote_init_tracefs(const char *name, struct trace_remote= *remote) { struct dentry *remote_d, *percpu_d, *d; @@ -452,6 +488,10 @@ static int trace_remote_init_tracefs(const char *name,= struct trace_remote *remo if (!d) goto err; =20 + d =3D trace_create_file("trace", TRACEFS_MODE_WRITE, remote_d, remote, &t= race_fops); + if (!d) + goto err; + percpu_d =3D tracefs_create_dir("per_cpu", remote_d); if (!percpu_d) { pr_err("Failed to create tracefs dir "TRACEFS_DIR"%s/per_cpu/\n", name); @@ -474,6 +514,11 @@ static int trace_remote_init_tracefs(const char *name,= struct trace_remote *remo &trace_pipe_fops); if (!d) goto err; + + d =3D trace_create_cpu_file("trace", TRACEFS_MODE_WRITE, cpu_d, remote, = cpu, + &trace_fops); + if (!d) + goto err; } =20 return 0; --=20 2.53.0.473.g4a7958ca14-goog