Michael S. Tsirkin
2023-Jun-02 11:15 UTC
[PATCH v2 5/6] tools/virtio: use canonical ftrace path
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 <zwisler at google.com>queued this too. thanks!> --- > 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