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

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Message-ID: <48cd594d-e06a-43e8-a825-18d477733aaf@quicinc.com>
Date: Fri, 23 Feb 2024 16:19:08 +0800
From: Huang Yiwei <quic_hyiwei@...cinc.com>
To: Steven Rostedt <rostedt@...dmis.org>
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 2/23/2024 9:47 AM, Steven Rostedt wrote:
> 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

My bad, will add the missing 'static' keyword in next patch.

Regards,
Huang Yiwei