linux-kernel - Re: [PATCH v5 2/5] tracing: Add __print_dynamic

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Message-ID: <20241002110641.3575c632@gandalf.local.home>
Date: Wed, 2 Oct 2024 11:06:41 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Avadhut Naik <avadhut.naik@....com>
Cc: <x86@...nel.org>, <linux-edac@...r.kernel.org>,
 <linux-trace-kernel@...r.kernel.org>, <linux-acpi@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>, <bp@...en8.de>, <tony.luck@...el.com>,
 <rafael@...nel.org>, <tglx@...utronix.de>, <mingo@...hat.com>,
 <lenb@...nel.org>, <mchehab@...nel.org>, <james.morse@....com>,
 <airlied@...il.com>, <yazen.ghannam@....com>, <john.allen@....com>,
 <avadnaik@....com>
Subject: Re: [PATCH v5 2/5] tracing: Add __print_dynamic_array() helper

On Tue, 1 Oct 2024 18:12:26 +0000
Avadhut Naik <avadhut.naik@....com> wrote:

> From: Steven Rostedt <rostedt@...dmis.org>
> 
> When printing a dynamic array in a trace event, the method is rather ugly.
> It has the format of:
> 
>   __print_array(__get_dynamic_array(array),
>             __get_dynmaic_array_len(array) / el_size, el_size)
> 
> Since dynamic arrays are known to the tracing infrastructure, create a
> helper macro that does the above for you.
> 
>   __print_dynamic_array(array, el_size)
> 
> Which would expand to the same output.
> 
> Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
> Signed-off-by: Avadhut Naik <avadhut.naik@....com>

I'm currently adding code where I need this patch too ;-)

I can make a branch that only has this patch based off of v6.12-rc1 where
we can both use it. Can we do that?

-- Steve


> ---
> Changes in v5:
> Patch introduced in the series.
> ---
>  include/trace/stages/stage3_trace_output.h | 8 ++++++++
>  include/trace/stages/stage7_class_define.h | 1 +
>  samples/trace_events/trace-events-sample.h | 7 ++++++-
>  3 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/include/trace/stages/stage3_trace_output.h b/include/trace/stages/stage3_trace_output.h
> index c1fb1355d309..8e3215093e1f 100644
> --- a/include/trace/stages/stage3_trace_output.h
> +++ b/include/trace/stages/stage3_trace_output.h
> @@ -119,6 +119,14 @@
>  		trace_print_array_seq(p, array, count, el_size);	\
>  	})
>  
> +#undef __print_dynamic_array
> +#define __print_dynamic_array(array, el_size)				\
> +	({								\
> +		__print_array(__get_dynamic_array(array),		\
> +			      __get_dynamic_array_len(array) / el_size,	\
> +			      el_size);					\
> +	})
> +
>  #undef __print_hex_dump
>  #define __print_hex_dump(prefix_str, prefix_type,			\
>  			 rowsize, groupsize, buf, len, ascii)		\
> diff --git a/include/trace/stages/stage7_class_define.h b/include/trace/stages/stage7_class_define.h
> index bcb960d16fc0..fcd564a590f4 100644
> --- a/include/trace/stages/stage7_class_define.h
> +++ b/include/trace/stages/stage7_class_define.h
> @@ -22,6 +22,7 @@
>  #undef __get_rel_cpumask
>  #undef __get_rel_sockaddr
>  #undef __print_array
> +#undef __print_dynamic_array
>  #undef __print_hex_dump
>  #undef __get_buf
>  
> diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h
> index 55f9a3da92d5..999f78d380ae 100644
> --- a/samples/trace_events/trace-events-sample.h
> +++ b/samples/trace_events/trace-events-sample.h
> @@ -319,7 +319,7 @@ TRACE_EVENT(foo_bar,
>  		__assign_cpumask(cpum, cpumask_bits(mask));
>  	),
>  
> -	TP_printk("foo %s %d %s %s %s %s %s (%s) (%s) %s", __entry->foo, __entry->bar,
> +	TP_printk("foo %s %d %s %s %s %s %s %s (%s) (%s) %s", __entry->foo, __entry->bar,
>  
>  /*
>   * Notice here the use of some helper functions. This includes:
> @@ -363,6 +363,11 @@ TRACE_EVENT(foo_bar,
>  		  __print_array(__get_dynamic_array(list),
>  				__get_dynamic_array_len(list) / sizeof(int),
>  				sizeof(int)),
> +
> +/*     A shortcut is to use __print_dynamic_array for dynamic arrays */
> +
> +		  __print_dynamic_array(list, sizeof(int)),
> +
>  		  __get_str(str), __get_str(lstr),
>  		  __get_bitmask(cpus), __get_cpumask(cpum),
>  		  __get_str(vstr))