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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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Johannes Berg 2011-11-24 20:03:08 +01:00 committed by Steven Rostedt
parent cdfb0d30e9
commit 9510035849
2 changed files with 46 additions and 0 deletions
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41
include/trace/events/printk.h Normal file
View File

@ -0,0 +1,41 @@
#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>

5
kernel/printk.c
View File

@ -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)) {