linux-kernel - [PATCH v2] tracing: Add __print_dynamic

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Message-ID: <20241018100318.0fd3c33b@gandalf.local.home>
Date: Fri, 18 Oct 2024 10:03:18 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: LKML <linux-kernel@...r.kernel.org>, Linux Trace Kernel
 <linux-trace-kernel@...r.kernel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, Avadhut Naik <avadhut.naik@....com>,
 "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>
Subject: [PATCH v2] tracing: Add __print_dynamic_array() helper

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.

Cc: Avadhut Naik <avadhut.naik@....com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
Changes since v1: https://lore.kernel.org/20240821134843.5faf9a15@gandalf.local.home

- Added parenthesis around el_size parameter in macro

 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..1e7b0bef95f5 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))
-- 
2.45.2