tracing: Add internal ftrace trace_puts() for ftrace to use

There's a few places that ftrace uses trace_printk() for internal
use, but this requires context (normal, softirq, irq, NMI) buffers
to keep things lockless. But the trace_puts() does not, as it can
write the string directly into the ring buffer. Make a internal helper
for trace_puts() and have the internal functions use that.

This way the extra context buffers are not used.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5043a0c4dde0ec55e7167d44fb1fcaa1c6db71a9..d372c6504c996b9b5543381844fcc319a3232c76 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -443,16 +443,16 @@ void tracing_snapshot(void)
        unsigned long flags;
 
        if (!tr->allocated_snapshot) {
-               trace_printk("*** SNAPSHOT NOT ALLOCATED ***\n");
-               trace_printk("*** stopping trace here!   ***\n");
+               internal_trace_puts("*** SNAPSHOT NOT ALLOCATED ***\n");
+               internal_trace_puts("*** stopping trace here!   ***\n");
                tracing_off();
                return;
        }
 
        /* Note, snapshot can not be used when the tracer uses it */
        if (tracer->use_max_tr) {
-               trace_printk("*** LATENCY TRACER ACTIVE ***\n");
-               trace_printk("*** Can not use snapshot (sorry) ***\n");
+               internal_trace_puts("*** LATENCY TRACER ACTIVE ***\n");
+               internal_trace_puts("*** Can not use snapshot (sorry) ***\n");
                return;
        }
 

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index d5764a8532e2fd90248e273d0d4a35ce37fb3bdc..0e430b401ab67f217eef5b5b00948cb1abefd47f 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1040,6 +1040,17 @@ void trace_printk_start_comm(void);
 int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set);
 int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled);
 
+/*
+ * Normal trace_printk() and friends allocates special buffers
+ * to do the manipulation, as well as saves the print formats
+ * into sections to display. But the trace infrastructure wants
+ * to use these without the added overhead at the price of being
+ * a bit slower (used mainly for warnings, where we don't care
+ * about performance). The internal_trace_puts() is for such
+ * a purpose.
+ */
+#define internal_trace_puts(str) __trace_puts(_THIS_IP_, str, strlen(str))
+
 #undef FTRACE_ENTRY
 #define FTRACE_ENTRY(call, struct_name, id, tstruct, print, filter)    \
        extern struct ftrace_event_call                                 \