tracing/ftrace: add the printk-msg-only option (66896a85) · Commits · 戴 / test

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:

Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

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
		};

		/*

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