tracing/function-graph-tracer: handle ftrace_printk entries
Handle the TRACE_PRINT entries from the function grapg tracer
and output them as a C comment just below the function that called
it, as if it was a comment inside this function.
Example with an ftrace_printk inside might_sleep() function:
void __might_sleep(char *file, int line)
{
static unsigned long prev_jiffy; /* ratelimiting */
ftrace_printk("Hi I'm a comment in might_sleep() :-)");
A chunk of a resulting trace:
0) | _reiserfs_free_block() {
0) | reiserfs_read_bitmap_block() {
0) | __bread() {
0) | __getblk() {
0) | __find_get_block() {
0) 0.698 us | mark_page_accessed();
0) 2.267 us | }
0) | __might_sleep() {
0) | /* Hi I'm a comment in might_sleep() :-) */
0) 1.321 us | }
0) 5.872 us | }
0) 7.313 us | }
0) 8.718 us | }
And this patch brings two minor fixes:
- The newline after a switch-out task has disappeared
- The "|" sign just before the cpu number on task-switch has been deleted.
0) 0.616 us | pick_next_task_rt();
0) 1.457 us | _spin_trylock();
0) 0.653 us | _spin_unlock();
0) 0.728 us | _spin_trylock();
0) 0.631 us | _spin_unlock();
0) 0.729 us | native_load_sp0();
0) 0.593 us | native_load_tls();
------------------------------------------
0) cat-2834 => migrati-3
------------------------------------------
0) | finish_task_switch() {
0) 0.841 us | _spin_unlock_irq();
0) 0.616 us | post_schedule_rt();
0) 3.882 us | }
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8b6409a..1ca74c0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3335,7 +3335,7 @@
int ret;
va_list args;
va_start(args, fmt);
- ret = trace_vprintk(0, fmt, args);
+ ret = trace_vprintk(0, -1, fmt, args);
va_end(args);
return ret;
}
@@ -3564,9 +3564,16 @@
return 0;
}
-int trace_vprintk(unsigned long ip, const char *fmt, va_list args)
+int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args)
{
- static DEFINE_SPINLOCK(trace_buf_lock);
+ /*
+ * Raw Spinlock because a normal spinlock would be traced here
+ * and append an irrelevant couple spin_lock_irqsave/
+ * spin_unlock_irqrestore traced by ftrace around this
+ * TRACE_PRINTK trace.
+ */
+ static raw_spinlock_t trace_buf_lock =
+ (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
static char trace_buf[TRACE_BUF_SIZE];
struct ring_buffer_event *event;
@@ -3587,7 +3594,8 @@
if (unlikely(atomic_read(&data->disabled)))
goto out;
- spin_lock_irqsave(&trace_buf_lock, flags);
+ local_irq_save(flags);
+ __raw_spin_lock(&trace_buf_lock);
len = vsnprintf(trace_buf, TRACE_BUF_SIZE, fmt, args);
len = min(len, TRACE_BUF_SIZE-1);
@@ -3601,13 +3609,15 @@
tracing_generic_entry_update(&entry->ent, flags, pc);
entry->ent.type = TRACE_PRINT;
entry->ip = ip;
+ entry->depth = depth;
memcpy(&entry->buf, trace_buf, len);
entry->buf[len] = 0;
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
out_unlock:
- spin_unlock_irqrestore(&trace_buf_lock, flags);
+ __raw_spin_unlock(&trace_buf_lock);
+ local_irq_restore(flags);
out:
preempt_enable_notrace();
@@ -3625,7 +3635,13 @@
return 0;
va_start(ap, fmt);
- ret = trace_vprintk(ip, fmt, ap);
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ ret = trace_vprintk(ip, current->curr_ret_stack, fmt, ap);
+#else
+ ret = trace_vprintk(ip, -1, fmt, ap);
+#endif
+
va_end(ap);
return ret;
}