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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Ross Zwisler <zwisler@chromium.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Ross Zwisler <zwisler@google.com>,
	Andrii Nakryiko <andrii@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-trace-kernel@vger.kernel.org,
	Mykola Lysenko <mykolal@fb.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
	Jiri Olsa <jolsa@kernel.org>, Shuah Khan <shuah@kernel.org>,
	bpf <bpf@vger.kernel.org>,
	"open list:KERNEL SELFTEST FRAMEWORK" 
	<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH 3/9] selftests/bpf: use canonical ftrace path
Date: Mon, 30 Jan 2023 11:52:03 -0800	[thread overview]
Message-ID: <CAADnVQJ7KxEK92qOz0Ya4MrACHpxngSpG4W38xuGEgZmXEG-vQ@mail.gmail.com> (raw)
In-Reply-To: <20230130181915.1113313-4-zwisler@google.com>

On Mon, Jan 30, 2023 at 10:19 AM Ross Zwisler <zwisler@chromium.org> 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
>
> Many tests in the bpf selftest code still refer to this older debugfs
> path, so let's update them to avoid confusion.

I wish that was the case, but in reality there are still systems
out there where tracefs is only mounted in that old location.
For example in one my VMs:

$ cat /proc/mounts |grep tracefs
tracefs /sys/kernel/debug/tracing tracefs rw,relatime 0 0
$ ls /sys/kernel/tracing/
$ uname -r
6.2.0-rc5-01030-gc1a3daf7363b

So this change will break the tests. We cannot do it.

  reply	other threads:[~2023-01-30 19:52 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-30 18:19 [PATCH 0/9] use canonical ftrace path whenever possible Ross Zwisler
2023-01-30 18:19 ` [PATCH 1/9] tracing: always use canonical ftrace path Ross Zwisler
2023-01-30 18:19 ` [PATCH 2/9] bpf: " Ross Zwisler
2023-01-30 18:19 ` [PATCH 3/9] selftests/bpf: " Ross Zwisler
2023-01-30 19:52   ` Alexei Starovoitov [this message]
2023-01-30 19:59     ` Steven Rostedt
2023-01-30 20:03       ` Alexei Starovoitov
2023-01-30 23:34         ` Steven Rostedt
2023-01-31  0:53           ` Alexei Starovoitov
2023-01-31 19:50             ` Steven Rostedt
2023-01-31 23:25               ` Alexei Starovoitov
2023-02-01  0:05                 ` Ross Zwisler
2023-01-30 18:19 ` [PATCH 4/9] perf docs: " Ross Zwisler
2023-02-02  1:24   ` Arnaldo Carvalho de Melo
2023-01-30 18:19 ` [PATCH 5/9] tools/power: " Ross Zwisler
2023-02-02 14:47   ` Rafael J. Wysocki
2023-01-30 18:19 ` [PATCH 6/9] selftests: " Ross Zwisler
2023-01-30 18:19 ` [PATCH 7/9] tools/virtio: " Ross Zwisler
2023-01-30 19:26   ` Michael S. Tsirkin
2023-02-01 22:07     ` Ross Zwisler
2023-01-30 18:19 ` [PATCH 8/9] leaking_addresses: also skip " Ross Zwisler
2023-01-30 19:34   ` Tycho Andersen
2023-01-30 18:19 ` [PATCH 9/9] tools/kvm_stat: use " Ross Zwisler
2023-01-30 19:26 ` [PATCH 0/9] use canonical ftrace path whenever possible Michael S. Tsirkin

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