Date:   Tue, 14 Feb 2023 09:23:48 -0700
From:   Ross Zwisler <zwisler@google.com>
To:     Stanislav Fomichev <sdf@google.com>
Cc:     Ross Zwisler <zwisler@chromium.org>, linux-kernel@vger.kernel.org,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Hao Luo <haoluo@google.com>, Jason Gunthorpe <jgg@ziepe.ca>,
        Jiri Olsa <jolsa@kernel.org>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Leon Romanovsky <leon@kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        Mykola Lysenko <mykolal@fb.com>, Shuah Khan <shuah@kernel.org>,
        Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
        bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-rdma@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>,
        linux-trace-kernel@vger.kernel.org,
        "Michael S . Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH bpf-next 1/2] bpf: use canonical ftrace path
Message-ID: <Y+u1lL49CB86VSuE@google.com>
References: <20230213221835.592763-1-zwisler@google.com>
 <Y+r4jLwWvhcvyuih@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Y+r4jLwWvhcvyuih@google.com>
Precedence: bulk

On Mon, Feb 13, 2023 at 06:57:16PM -0800, Stanislav Fomichev wrote:
> On 02/13, 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
> 
> > Many comments and samples in the bpf code still refer to this older
> > debugfs path, so let's update them to avoid confusion.  There are a few
> > spots where the bpf code explicitly checks both tracefs and debugfs
> > (tools/bpf/bpftool/tracelog.c and tools/lib/api/fs/fs.c) and I've left
> > those alone so that the tools can continue to work with both paths.
> 
> Doesn't seem to apply cleanly to bpf-next?
> 
> https://github.com/kernel-patches/bpf/pull/4584

Oh, apologies, I was using Linus's master branch as my baseline.
I'll send out a v2.