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Message-ID: <48cd594d-e06a-43e8-a825-18d477733aaf@quicinc.com>
Date: Fri, 23 Feb 2024 16:19:08 +0800
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Subject: Re: [PATCH v5] tracing: Support to dump instance traces by
 ftrace_dump_on_oops
To: Steven Rostedt <rostedt@goodmis.org>
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>
References: <20240208131814.614691-1-quic_hyiwei@quicinc.com>
 <20240222204701.6b9de71e@gandalf.local.home>
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From: Huang Yiwei <quic_hyiwei@quicinc.com>
In-Reply-To: <20240222204701.6b9de71e@gandalf.local.home>
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On 2/23/2024 9:47 AM, Steven Rostedt wrote:
> 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.
>>
>> 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@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 ‘ftrace_dump_one’ [-Wmissing-prototypes]
> 
> -- Steve

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

Regards,
Huang Yiwei