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Commit bea6957d authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Steven Rostedt (VMware)
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tracing: Simplify printf'ing in seq_print_sym 

trace_seq_printf(..., "%s", ...) can be done with trace_seq_puts()
instead, avoiding printf overhead. In the second instance, the string
we're copying was just created from an snprintf() to a stack buffer, so
we might as well do that printf directly. This naturally leads to moving
the declaration of the str buffer inside the CONFIG_KALLSYMS guard,
which in turn will make gcc inline the function for !CONFIG_KALLSYMS (it
only has a single caller, but the huge stack frame seems to make gcc not
inline it for CONFIG_KALLSYMS).

Link: http://lkml.kernel.org/r/20181029223542.26175-4-linux@rasmusvillemoes.dk



Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent cc9f59fb

kernel/trace/trace_output.c

+3 −4
Original line number Diff line number Diff line
@@ -341,8 +341,8 @@ static inline const char *kretprobed(const char *name) 
static void

seq_print_sym(struct trace_seq *s, unsigned long address, bool offset)

{

	char str[KSYM_SYMBOL_LEN];

#ifdef CONFIG_KALLSYMS

	char str[KSYM_SYMBOL_LEN];

	const char *name;



	if (offset)
@@ -352,12 +352,11 @@ seq_print_sym(struct trace_seq *s, unsigned long address, bool offset) 
	name = kretprobed(str);



	if (name && strlen(name)) {

		trace_seq_printf(s, "%s", name);

		trace_seq_puts(s, name);

		return;

	}

#endif

	snprintf(str, KSYM_SYMBOL_LEN, "0x%08lx", address);

	trace_seq_printf(s, "%s", str);

	trace_seq_printf(s, "0x%08lx", address);

}



#ifndef CONFIG_64BIT