trace: Add CONFIG_DISABLE_TRACE_PRINTK option

Poorly made kernel trees often use trace_printk() without properly guarding them in a #ifdef macro. Such usage of trace_printk() causes a warning at boot and additional memory allocation. This option serves to disable those all at once with ease. Signed-off-by: Park Ju Hyung <[email protected]> Signed-off-by: Alex Naidis <[email protected]> Signed-off-by: UtsavBalar1231 <[email protected]> Change-Id: I7af2f2d3ba700fc53d5f573ed13c0210adfe11c9
UtsavBalar1231 · May 2, 2022 · 43b668b · 43b668b
1 parent 6581493
commit 43b668b
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diff --git a/include/linux/kernel.h b/include/linux/kernel.h
@@ -687,6 +687,9 @@ do {									\
  * let gcc optimize the rest.
  */
 
+#ifdef CONFIG_DISABLE_TRACE_PRINTK
+#define trace_printk pr_debug
+#else
 #define trace_printk(fmt, ...)				\
 do {							\
 	char _______STR[] = __stringify((__VA_ARGS__));	\
@@ -709,6 +712,7 @@ do {									\
 	else								\
 		__trace_printk(_THIS_IP_, fmt, ##args);			\
 } while (0)
+#endif
 
 extern __printf(2, 3)
 int __trace_bprintk(unsigned long ip, const char *fmt, ...);

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
@@ -146,6 +146,20 @@ config GENERIC_TRACER
 	bool
 	select TRACING
 
+if TRACING
+
+config DISABLE_TRACE_PRINTK
+	bool "Force disable trace_printk() usage"
+	default y
+	help
+	  When trace_printk() is used in any of the kernel source, it enables
+	  debugging functions which are not desired for production kernel.
+	  Enabling this option will replace trace_printk() with pr_debug().
+
+	  If in doubt, say Y.
+
+endif
+
 #
 # Minimum requirements an architecture has to meet for us to
 # be able to offer generic tracing facilities: