Re: [PATCH v2 0/6] use canonical ftrace path whenever possible

Re: [PATCH v2 0/6] use canonical ftrace path whenever possible

[Michael S. Tsirkin]

On Wed, Feb 15, 2023 at 03:33:44PM -0700, Ross Zwisler wrote:
> Changes in v2:
>  * Dropped patches which were pulled into maintainer trees.
>  * Split BPF patches out into another series targeting bpf-next.
>  * trace-agent now falls back to debugfs if tracefs isn't present.
>  * Added Acked-by from mst@redhat.com to series.
>  * Added a typo fixup for the virtio-trace README.
> 
> Steven, assuming there are no objections, would you feel comfortable
> taking this series through your tree?

Acked-by: Michael S. Tsirkin <mst@redhat.com>

if you want the virtio patches through my tree after all, let me know.

> ---
> 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
> 
> There are many places where this older debugfs path is still used in
> code comments, selftests, examples and tools, so let's update them to
> avoid confusion.
> 
> I've broken up the series as best I could by maintainer or directory,
> and I've only sent people the patches that I think they care about to
> avoid spamming everyone.
> 
> Ross Zwisler (6):
>   tracing: always use canonical ftrace path
>   selftests: use canonical ftrace path
>   leaking_addresses: also skip canonical ftrace path
>   tools/kvm_stat: use canonical ftrace path
>   tools/virtio: use canonical ftrace path
>   tools/virtio: fix typo in README instructions
> 
>  include/linux/kernel.h                        |  2 +-
>  include/linux/tracepoint.h                    |  4 ++--
>  kernel/trace/Kconfig                          | 20 +++++++++----------
>  kernel/trace/kprobe_event_gen_test.c          |  2 +-
>  kernel/trace/ring_buffer.c                    |  2 +-
>  kernel/trace/synth_event_gen_test.c           |  2 +-
>  kernel/trace/trace.c                          |  2 +-
>  samples/user_events/example.c                 |  4 ++--
>  scripts/leaking_addresses.pl                  |  1 +
>  scripts/tracing/draw_functrace.py             |  6 +++---
>  tools/kvm/kvm_stat/kvm_stat                   |  2 +-
>  tools/lib/api/fs/tracing_path.c               |  4 ++--
>  .../testing/selftests/user_events/dyn_test.c  |  2 +-
>  .../selftests/user_events/ftrace_test.c       | 10 +++++-----
>  .../testing/selftests/user_events/perf_test.c |  8 ++++----
>  tools/testing/selftests/vm/protection_keys.c  |  4 ++--
>  tools/tracing/latency/latency-collector.c     |  2 +-
>  tools/virtio/virtio-trace/README              |  4 ++--
>  tools/virtio/virtio-trace/trace-agent.c       | 12 +++++++----
>  19 files changed, 49 insertions(+), 44 deletions(-)
> 
> -- 
> 2.39.1.637.g21b0678d19-goog

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Re: [PATCH v2 0/6] use canonical ftrace path whenever possible

[Steven Rostedt]

On Fri, 10 Mar 2023 12:06:58 -0700
Ross Zwisler <zwisler@google.com> wrote:

> On Fri, Mar 10, 2023 at 03:29:49AM -0500, Michael S. Tsirkin wrote:
> > On Wed, Feb 15, 2023 at 03:33:44PM -0700, Ross Zwisler wrote:  
> > > Changes in v2:
> > >  * Dropped patches which were pulled into maintainer trees.
> > >  * Split BPF patches out into another series targeting bpf-next.
> > >  * trace-agent now falls back to debugfs if tracefs isn't present.
> > >  * Added Acked-by from mst@redhat.com to series.
> > >  * Added a typo fixup for the virtio-trace README.
> > > 
> > > Steven, assuming there are no objections, would you feel comfortable
> > > taking this series through your tree?  
> > 
> > Acked-by: Michael S. Tsirkin <mst@redhat.com>
> > 
> > if you want the virtio patches through my tree after all, let me know.  
> 
> Yes, please, that would be great.  I'll send out v3 with the few patches that
> haven't gotten a response, but I'll drop the virtio patches assuming you've
> got them.
>

Since the last patch 6/6 is not tracing related, I would prefer it to go
through the virtio tree.

For patches 1-5, please add:

Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Thanks!

-- Steve
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Re: [PATCH v2 0/6] use canonical ftrace path whenever possible

[Michael S. Tsirkin]

On Wed, Feb 15, 2023 at 03:33:44PM -0700, Ross Zwisler wrote:
> Changes in v2:
>  * Dropped patches which were pulled into maintainer trees.
>  * Split BPF patches out into another series targeting bpf-next.
>  * trace-agent now falls back to debugfs if tracefs isn't present.
>  * Added Acked-by from mst@redhat.com to series.
>  * Added a typo fixup for the virtio-trace README.
> 
> Steven, assuming there are no objections, would you feel comfortable
> taking this series through your tree?

for merging up to patch 5 through another tree:

Acked-by: Michael S. Tsirkin <mst@redhat.com>

I'll merge patch 6, no problem.


> ---
> 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
> 
> There are many places where this older debugfs path is still used in
> code comments, selftests, examples and tools, so let's update them to
> avoid confusion.
> 
> I've broken up the series as best I could by maintainer or directory,
> and I've only sent people the patches that I think they care about to
> avoid spamming everyone.
> 
> Ross Zwisler (6):
>   tracing: always use canonical ftrace path
>   selftests: use canonical ftrace path
>   leaking_addresses: also skip canonical ftrace path
>   tools/kvm_stat: use canonical ftrace path
>   tools/virtio: use canonical ftrace path
>   tools/virtio: fix typo in README instructions
> 
>  include/linux/kernel.h                        |  2 +-
>  include/linux/tracepoint.h                    |  4 ++--
>  kernel/trace/Kconfig                          | 20 +++++++++----------
>  kernel/trace/kprobe_event_gen_test.c          |  2 +-
>  kernel/trace/ring_buffer.c                    |  2 +-
>  kernel/trace/synth_event_gen_test.c           |  2 +-
>  kernel/trace/trace.c                          |  2 +-
>  samples/user_events/example.c                 |  4 ++--
>  scripts/leaking_addresses.pl                  |  1 +
>  scripts/tracing/draw_functrace.py             |  6 +++---
>  tools/kvm/kvm_stat/kvm_stat                   |  2 +-
>  tools/lib/api/fs/tracing_path.c               |  4 ++--
>  .../testing/selftests/user_events/dyn_test.c  |  2 +-
>  .../selftests/user_events/ftrace_test.c       | 10 +++++-----
>  .../testing/selftests/user_events/perf_test.c |  8 ++++----
>  tools/testing/selftests/vm/protection_keys.c  |  4 ++--
>  tools/tracing/latency/latency-collector.c     |  2 +-
>  tools/virtio/virtio-trace/README              |  4 ++--
>  tools/virtio/virtio-trace/trace-agent.c       | 12 +++++++----
>  19 files changed, 49 insertions(+), 44 deletions(-)
> 
> -- 
> 2.39.1.637.g21b0678d19-goog

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Re: [PATCH v2 5/6] tools/virtio: use canonical ftrace path

[Michael S. Tsirkin]

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

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