| Message ID | 20230215223350.2658616-6-zwisler@google.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | use canonical ftrace path whenever possible | expand |
On 2/16/2023 4:03 AM, 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@google.com> > --- > 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); > + } > Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com> -Mukesh > if (ret <= 0) { > pr_err("Failed to generate %s path(CPU#%d):%d\n",
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@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
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",
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@google.com> --- tools/virtio/virtio-trace/README | 2 +- tools/virtio/virtio-trace/trace-agent.c | 12 ++++++++---- 2 files changed, 9 insertions(+), 5 deletions(-)