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Commit 66896a85 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Ingo Molnar
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tracing/ftrace: add the printk-msg-only option 



Impact: display ftrace_printk messages "as is"

By default, ftrace_printk() messages find their output with some other
informations like pid, caller, ...
Sometimes a developer just want to have the ftrace_printk left "as is", without
other information.

This is done by providing a default-off option called printk-msg-only.
To enable it, just do `echo printk-msg-only > /debugfs/tracing/trace_options`

Before the patch:

           <...>-2739  [000]   145.692153: __might_sleep: I'm an ftrace_printk msg in __might_sleep
           <...>-2739  [000]   145.692155: __might_sleep: I'm another ftrace_printk msg in __might_sleep

After the patch and the printk-msg-only option enabled:

I'm an ftrace_printk msg in __might_sleep
I'm another ftrace_printk msg in __might_sleep

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 2c2d7329

kernel/trace/trace.c

+25 −0
Original line number Diff line number Diff line
@@ -287,6 +287,7 @@ static const char *trace_options[] = { 
	"annotate",

	"userstacktrace",

	"sym-userobj",

	"printk-msg-only",

	NULL

};
@@ -2265,6 +2266,25 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter) 
	return TRACE_TYPE_HANDLED;

}



static enum print_line_t print_printk_msg_only(struct trace_iterator *iter)

{

	struct trace_seq *s = &iter->seq;

	struct trace_entry *entry = iter->ent;

	struct print_entry *field;

	int ret;



	trace_assign_type(field, entry);



	ret = trace_seq_printf(s, field->buf);

	if (!ret)

		return TRACE_TYPE_PARTIAL_LINE;



	if (entry->flags & TRACE_FLAG_CONT)

		trace_seq_print_cont(s, iter);



	return TRACE_TYPE_HANDLED;

}



static enum print_line_t print_bin_fmt(struct trace_iterator *iter)

{

	struct trace_seq *s = &iter->seq;
@@ -2345,6 +2365,11 @@ static enum print_line_t print_trace_line(struct trace_iterator *iter) 
			return ret;

	}



	if (iter->ent->type == TRACE_PRINT &&

			trace_flags & TRACE_ITER_PRINTK &&

			trace_flags & TRACE_ITER_PRINTK_MSGONLY)

		return print_printk_msg_only(iter);



	if (trace_flags & TRACE_ITER_BIN)

		return print_bin_fmt(iter);

kernel/trace/trace.h

+2 −1
Original line number Diff line number Diff line
@@ -578,7 +578,8 @@ enum trace_iterator_flags { 
	TRACE_ITER_BRANCH		= 0x1000,

	TRACE_ITER_ANNOTATE		= 0x2000,

	TRACE_ITER_USERSTACKTRACE       = 0x4000,

	TRACE_ITER_SYM_USEROBJ          = 0x8000

	TRACE_ITER_SYM_USEROBJ          = 0x8000,

	TRACE_ITER_PRINTK_MSGONLY	= 0x10000

};



/*