ftrace: nmi update statistics

Impact: add more debug info to /debugfs/tracing/dyn_ftrace_total_info

This patch adds dynamic ftrace NMI update statistics to the
/debugfs/tracing/dyn_ftrace_total_info stat file.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 24 insertions, 7 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a610ca771558..bc36febc0771 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2815,22 +2815,39 @@ static struct file_operations tracing_mark_fops = {
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
+#define DYN_INFO_BUF_SIZE 1023
+static char ftrace_dyn_info_buffer[DYN_INFO_BUF_SIZE+1];
+static DEFINE_MUTEX(dyn_info_mutex);
+
+int __weak ftrace_arch_read_dyn_info(char *buf, int size)
+{
+        return 0;
+}
+
 static ssize_t
-tracing_read_long(struct file *filp, char __user *ubuf,
+tracing_read_dyn_info(struct file *filp, char __user *ubuf,
                   size_t cnt, loff_t *ppos)
 {
         unsigned long *p = filp->private_data;
-        char buf[64];
+        char *buf = ftrace_dyn_info_buffer;
         int r;
 
-        r = sprintf(buf, "%ld\n", *p);
+        mutex_lock(&dyn_info_mutex);
+        r = sprintf(buf, "%ld ", *p);
 
-        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+        r += ftrace_arch_read_dyn_info(buf+r, DYN_INFO_BUF_SIZE-r);
+        buf[r++] = '\n';
+
+        r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+
+        mutex_unlock(&dyn_info_mutex);
+
+        return r;
 }
 
-static struct file_operations tracing_read_long_fops = {
+static struct file_operations tracing_dyn_info_fops = {
         .open           = tracing_open_generic,
-        .read           = tracing_read_long,
+        .read           = tracing_read_dyn_info,
 };
 #endif
 
@@ -2939,7 +2956,7 @@ static __init int tracer_init_debugfs(void)
 #ifdef CONFIG_DYNAMIC_FTRACE
         entry = debugfs_create_file("dyn_ftrace_total_info", 0444, d_tracer,
                                     &ftrace_update_tot_cnt,
-                                    &tracing_read_long_fops);
+                                    &tracing_dyn_info_fops);
         if (!entry)
                 pr_warning("Could not create debugfs "
                            "'dyn_ftrace_total_info' entry\n");