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AJvYcCVRfhNO/M1hRVi6DAD8Vlw5Z64yyr1oQ8GJAsbJOddZR7FGX9uwlWw5ZpxqHLmtGKw+o85GOYRZn8uj80s=@vger.kernel.org X-Gm-Message-State: AOJu0YzmN17Nb4al5yN/N1qtTOL1CxPyKWP4K75IW/tUbXgLx7QT3u59 muhP/9T5nNNN0VuXNvQHVeMEDDwQnhY0I1FcB+YKkfbZtqJQP+mTgmLMF2EZBURWQ5iewxaSoBu p4KoNyPfpWHNOpS/7ed+aUQ== X-Google-Smtp-Source: AGHT+IHxHGYd1KeGVGM3iasiEuHwtuNNyEruew1KNtvROKmeBVTKi8SlkdS/376itCy6PY0wJZqfEhcdRnlQxCNH X-Received: from wmbez8.prod.google.com ([2002:a05:600c:83c8:b0:459:e17c:3572]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:1f0e:b0:45b:47e1:ef76 with SMTP id 5b1f17b1804b1-45b4d86c5d6mr9909145e9.37.1755764065317; Thu, 21 Aug 2025 01:14:25 -0700 (PDT) Date: Thu, 21 Aug 2025 09:13:52 +0100 In-Reply-To: <20250821081412.1008261-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250821081412.1008261-1-vdonnefort@google.com> X-Mailer: git-send-email 2.51.0.rc2.233.g662b1ed5c5-goog Message-ID: <20250821081412.1008261-5-vdonnefort@google.com> Subject: [PATCH v6 04/24] 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" For standard trace instance, "trace" files allow to do non-consuming read of the ring-buffers. This is however not applicable to ring-buffer remotes due to the lack of support in the meta-page. Nonetheless this file is still useful to reset a ring-buffer so let's add a write-only version. Signed-off-by: Vincent Donnefort diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index de043a6f2fe0..1aa99da3c96a 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -11,6 +11,7 @@ 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 1a4786b7970c..18b2930186cc 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 remote->trace_buffer_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_remote(rb_remote); if (!remote->trace_buffer) { remote->cbs->unload_trace_buffer(remote->trace_buffer_desc, remote->priv= ); @@ -136,6 +137,21 @@ 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) { @@ -370,6 +386,26 @@ 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; @@ -400,7 +436,9 @@ static int trace_remote_init_tracefs(const char *name, = struct trace_remote *remo !trace_create_file("buffer_size_kb", TRACEFS_MODE_WRITE, remote_d, re= mote, &buffer_size_kb_fops) || !trace_create_file("trace_pipe", TRACEFS_MODE_READ, remote_d, remote, - &trace_pipe_fops)) + &trace_pipe_fops) || + !trace_create_file("trace", 0200, remote_d, remote, + &trace_fops)) goto err; =20 percpu_d =3D tracefs_create_dir("per_cpu", remote_d); @@ -422,7 +460,9 @@ static int trace_remote_init_tracefs(const char *name, = struct trace_remote *remo } =20 if (!trace_create_cpu_file("trace_pipe", TRACEFS_MODE_READ, cpu_d, remot= e, cpu, - &trace_pipe_fops)) + &trace_pipe_fops) || + !trace_create_cpu_file("trace", 0200, cpu_d, remote, cpu, + &trace_fops)) goto err; } =20 --=20 2.51.0.rc2.233.g662b1ed5c5-goog