Re: [PATCH v2 5/6] tools/virtio: use canonical ftrace path
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2023-06-02 11:18:53
Also in:
lkml, virtualization
On Wed, Feb 15, 2023 at 03:33:49PM -0700, Ross Zwisler wrote:
The canonical location for the tracefs filesystem is at /sys/kernel/tracing. But, from Documentation/trace/ftrace.rst: Before 4.1, all ftrace tracing control files were within the debugfs file system, which is typically located at /sys/kernel/debug/tracing. For backward compatibility, when mounting the debugfs file system, the tracefs file system will be automatically mounted at: /sys/kernel/debug/tracing A few spots in tools/virtio still refer to this older debugfs path, so let's update them to avoid confusion. Signed-off-by: Ross Zwisler <redacted>
queued this too. thanks!
quoted hunk ↗ jump to hunk
--- tools/virtio/virtio-trace/README | 2 +- tools/virtio/virtio-trace/trace-agent.c | 12 ++++++++---- 2 files changed, 9 insertions(+), 5 deletions(-)diff --git a/tools/virtio/virtio-trace/README b/tools/virtio/virtio-trace/README index b64845b823ab..cea29a2a4c0a 100644 --- a/tools/virtio/virtio-trace/README +++ b/tools/virtio/virtio-trace/README@@ -95,7 +95,7 @@ Run 1) Enable ftrace in the guest <Example> - # echo 1 > /sys/kernel/debug/tracing/events/sched/enable + # echo 1 > /sys/kernel/tracing/events/sched/enable 2) Run trace agent in the guest This agent must be operated as root.diff --git a/tools/virtio/virtio-trace/trace-agent.c b/tools/virtio/virtio-trace/trace-agent.c index cdfe77c2b4c8..7e2d9bbf0b84 100644 --- a/tools/virtio/virtio-trace/trace-agent.c +++ b/tools/virtio/virtio-trace/trace-agent.c@@ -18,8 +18,9 @@ #define PIPE_DEF_BUFS 16 #define PIPE_MIN_SIZE (PAGE_SIZE*PIPE_DEF_BUFS) #define PIPE_MAX_SIZE (1024*1024) -#define READ_PATH_FMT \ - "/sys/kernel/debug/tracing/per_cpu/cpu%d/trace_pipe_raw" +#define TRACEFS "/sys/kernel/tracing" +#define DEBUGFS "/sys/kernel/debug/tracing" +#define READ_PATH_FMT "%s/per_cpu/cpu%d/trace_pipe_raw" #define WRITE_PATH_FMT "/dev/virtio-ports/trace-path-cpu%d" #define CTL_PATH "/dev/virtio-ports/agent-ctl-path"@@ -120,9 +121,12 @@ static const char *make_path(int cpu_num, bool this_is_write_path) if (this_is_write_path) /* write(output) path */ ret = snprintf(buf, PATH_MAX, WRITE_PATH_FMT, cpu_num); - else + else { /* read(input) path */ - ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, cpu_num); + ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, TRACEFS, cpu_num); + if (ret > 0 && access(buf, F_OK) != 0) + ret = snprintf(buf, PATH_MAX, READ_PATH_FMT, DEBUGFS, cpu_num); + } if (ret <= 0) { pr_err("Failed to generate %s path(CPU#%d):%d\n",-- 2.39.1.637.g21b0678d19-goog