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Date: Thu, 22 Feb 2024 20:47:01 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: Huang Yiwei <quic_hyiwei@quicinc.com>
Cc: <mhiramat@kernel.org>, <mark.rutland@arm.com>, <mcgrof@kernel.org>,
 <keescook@chromium.org>, <j.granados@samsung.com>,
 <mathieu.desnoyers@efficios.com>, <corbet@lwn.net>,
 <linux-kernel@vger.kernel.org>, <linux-trace-kernel@vger.kernel.org>,
 <linux-fsdevel@vger.kernel.org>, <linux-doc@vger.kernel.org>,
 <quic_bjorande@quicinc.com>, <quic_tsoni@quicinc.com>,
 <quic_satyap@quicinc.com>, <quic_aiquny@quicinc.com>, <kernel@quicinc.com>,
 Ross Zwisler <zwisler@google.com>, Joel Fernandes <joel@joelfernandes.org>
Subject: Re: [PATCH v5] tracing: Support to dump instance traces by
 ftrace_dump_on_oops
Message-ID: <20240222204701.6b9de71e@gandalf.local.home>
In-Reply-To: <20240208131814.614691-1-quic_hyiwei@quicinc.com>
References: <20240208131814.614691-1-quic_hyiwei@quicinc.com>
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On Thu, 8 Feb 2024 21:18:14 +0800
Huang Yiwei <quic_hyiwei@quicinc.com> wrote:

> Currently ftrace only dumps the global trace buffer on an OOPs. For
> debugging a production usecase, instance trace will be helpful to
> check specific problems since global trace buffer may be used for
> other purposes.
>=20
> This patch extend the ftrace_dump_on_oops parameter to dump a specific
> or multiple trace instances:
>=20
>   - ftrace_dump_on_oops=3D0: as before -- don't dump
>   - ftrace_dump_on_oops[=3D1]: as before -- dump the global trace buffer
>   on all CPUs
>   - ftrace_dump_on_oops=3D2 or =3Dorig_cpu: as before -- dump the global
>   trace buffer on CPU that triggered the oops
>   - ftrace_dump_on_oops=3D<instance_name>: new behavior -- dump the
>   tracing instance matching <instance_name>
>   - ftrace_dump_on_oops[=3D2/orig_cpu],<instance1_name>[=3D2/orig_cpu],
>   <instrance2_name>[=3D2/orig_cpu]: new behavior -- dump the global trace
>   buffer and multiple instance buffer on all CPUs, or only dump on CPU
>   that triggered the oops if =3D2 or =3Dorig_cpu is given
>=20
> Also, the sysctl node can handle the input accordingly.
>=20
> Cc: Ross Zwisler <zwisler@google.com>
> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
> Signed-off-by: Huang Yiwei <quic_hyiwei@quicinc.com>

This patch failed with the following warning:

  kernel/trace/trace.c:10029:6: warning: no previous prototype for =E2=80=
=98ftrace_dump_one=E2=80=99 [-Wmissing-prototypes]

-- Steve