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: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index f06fb89..54373d9 100644 (file)
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -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