linux-kernel - Re: [PATCH v5] tracing: Support to dump instance traces by ftrace_dump_on

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Message-ID: <20240222204701.6b9de71e@gandalf.local.home>
Date: Thu, 22 Feb 2024 20:47:01 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Huang Yiwei <quic_hyiwei@...cinc.com>
Cc: <mhiramat@...nel.org>, <mark.rutland@....com>, <mcgrof@...nel.org>,
 <keescook@...omium.org>, <j.granados@...sung.com>,
 <mathieu.desnoyers@...icios.com>, <corbet@....net>,
 <linux-kernel@...r.kernel.org>, <linux-trace-kernel@...r.kernel.org>,
 <linux-fsdevel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
 <quic_bjorande@...cinc.com>, <quic_tsoni@...cinc.com>,
 <quic_satyap@...cinc.com>, <quic_aiquny@...cinc.com>, <kernel@...cinc.com>,
 Ross Zwisler <zwisler@...gle.com>, Joel Fernandes <joel@...lfernandes.org>
Subject: Re: [PATCH v5] tracing: Support to dump instance traces by
 ftrace_dump_on_oops

On Thu, 8 Feb 2024 21:18:14 +0800
Huang Yiwei <quic_hyiwei@...cinc.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.
> 
> This patch extend the ftrace_dump_on_oops parameter to dump a specific
> or multiple trace instances:
> 
>   - ftrace_dump_on_oops=0: as before -- don't dump
>   - ftrace_dump_on_oops[=1]: as before -- dump the global trace buffer
>   on all CPUs
>   - ftrace_dump_on_oops=2 or =orig_cpu: as before -- dump the global
>   trace buffer on CPU that triggered the oops
>   - ftrace_dump_on_oops=<instance_name>: new behavior -- dump the
>   tracing instance matching <instance_name>
>   - ftrace_dump_on_oops[=2/orig_cpu],<instance1_name>[=2/orig_cpu],
>   <instrance2_name>[=2/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 =2 or =orig_cpu is given
> 
> Also, the sysctl node can handle the input accordingly.
> 
> Cc: Ross Zwisler <zwisler@...gle.com>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
> Signed-off-by: Huang Yiwei <quic_hyiwei@...cinc.com>

This patch failed with the following warning:

  kernel/trace/trace.c:10029:6: warning: no previous prototype for ‘ftrace_dump_one’ [-Wmissing-prototypes]

-- Steve