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Commit 95100358 authored by Johannes Berg's avatar Johannes Berg Committed by Steven Rostedt
Browse files

printk/tracing: Add console output tracing 

Add a printk.console trace point to record any printk
messages into the trace, regardless of the current
console loglevel. This can help correlate (existing)
printk debugging with other tracing.

Link: http://lkml.kernel.org/r/1322161388.5366.54.camel@jlt3.sipsolutions.net



Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent cdfb0d30

include/trace/events/printk.h

0 → 100644
+41 −0
Original line number Diff line number Diff line 
#undef TRACE_SYSTEM

#define TRACE_SYSTEM printk



#if !defined(_TRACE_PRINTK_H) || defined(TRACE_HEADER_MULTI_READ)

#define _TRACE_PRINTK_H



#include <linux/tracepoint.h>



TRACE_EVENT_CONDITION(console,

	TP_PROTO(const char *log_buf, unsigned start, unsigned end,

		 unsigned log_buf_len),



	TP_ARGS(log_buf, start, end, log_buf_len),



	TP_CONDITION(start != end),



	TP_STRUCT__entry(

		__dynamic_array(char, msg, end - start + 1)

	),



	TP_fast_assign(

		if ((start & (log_buf_len - 1)) > (end & (log_buf_len - 1))) {

			memcpy(__get_dynamic_array(msg),

			       log_buf + (start & (log_buf_len - 1)),

			       log_buf_len - (start & (log_buf_len - 1)));

			memcpy((char *)__get_dynamic_array(msg) +

			       log_buf_len - (start & (log_buf_len - 1)),

			       log_buf, end & (log_buf_len - 1));

		} else

			memcpy(__get_dynamic_array(msg),

			       log_buf + (start & (log_buf_len - 1)),

			       end - start);

		((char *)__get_dynamic_array(msg))[end - start] = 0;

	),



	TP_printk("%s", __get_str(msg))

);

#endif /* _TRACE_PRINTK_H */



/* This part must be outside protection */

#include <trace/define_trace.h>

kernel/printk.c

+5 −0
Original line number Diff line number Diff line
@@ -44,6 +44,9 @@ 


#include <asm/uaccess.h>



#define CREATE_TRACE_POINTS

#include <trace/events/printk.h>



/*

 * Architectures can override it:

 */
@@ -542,6 +545,8 @@ MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to" 
static void _call_console_drivers(unsigned start,

				unsigned end, int msg_log_level)

{

	trace_console(&LOG_BUF(0), start, end, log_buf_len);



	if ((msg_log_level < console_loglevel || ignore_loglevel) &&

			console_drivers && start != end) {

		if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) {