ftrace: add self-tests

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 61 insertions, 2 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9bad2379115a..f6d026f17dbb 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -32,6 +32,8 @@
 unsigned long __read_mostly     tracing_max_latency = (cycle_t)ULONG_MAX;
 unsigned long __read_mostly     tracing_thresh;
 
+static int tracing_disabled = 1;
+
 static long notrace
 ns2usecs(cycle_t nsec)
 {
@@ -217,11 +219,48 @@ int register_tracer(struct tracer *type)
                 }
         }
 
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+        if (type->selftest) {
+                struct tracer *saved_tracer = current_trace;
+                struct trace_array_cpu *data;
+                struct trace_array *tr = &global_trace;
+                int saved_ctrl = tr->ctrl;
+                int i;
+                /*
+                 * Run a selftest on this tracer.
+                 * Here we reset the trace buffer, and set the current
+                 * tracer to be this tracer. The tracer can then run some
+                 * internal tracing to verify that everything is in order.
+                 * If we fail, we do not register this tracer.
+                 */
+                for_each_possible_cpu(i) {
+                        if (!data->trace)
+                                continue;
+                        data = tr->data[i];
+                        tracing_reset(data);
+                }
+                current_trace = type;
+                tr->ctrl = 0;
+                /* the test is responsible for initializing and enabling */
+                pr_info("Testing tracer %s: ", type->name);
+                ret = type->selftest(type, tr);
+                /* the test is responsible for resetting too */
+                current_trace = saved_tracer;
+                tr->ctrl = saved_ctrl;
+                if (ret) {
+                        printk(KERN_CONT "FAILED!\n");
+                        goto out;
+                }
+                printk(KERN_CONT "PASSED\n");
+        }
+#endif
+
         type->next = trace_types;
         trace_types = type;
         len = strlen(type->name);
         if (len > max_tracer_type_len)
                 max_tracer_type_len = len;
+
  out:
         mutex_unlock(&trace_types_lock);
 
@@ -985,6 +1024,11 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
 {
         struct trace_iterator *iter;
 
+        if (tracing_disabled) {
+                *ret = -ENODEV;
+                return NULL;
+        }
+
         iter = kzalloc(sizeof(*iter), GFP_KERNEL);
         if (!iter) {
                 *ret = -ENOMEM;
@@ -1023,6 +1067,9 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
 
 int tracing_open_generic(struct inode *inode, struct file *filp)
 {
+        if (tracing_disabled)
+                return -ENODEV;
+
         filp->private_data = inode->i_private;
         return 0;
 }
@@ -1128,6 +1175,9 @@ static int show_traces_open(struct inode *inode, struct file *file)
 {
         int ret;
 
+        if (tracing_disabled)
+                return -ENODEV;
+
         ret = seq_open(file, &show_traces_seq_ops);
         if (!ret) {
                 struct seq_file *m = file->private_data;
@@ -1452,6 +1502,11 @@ struct dentry *tracing_init_dentry(void)
         return d_tracer;
 }
 
+#ifdef CONFIG_FTRACE_SELFTEST
+/* Let selftest have access to static functions in this file */
+#include "trace_selftest.c"
+#endif
+
 static __init void tracer_init_debugfs(void)
 {
         struct dentry *d_tracer;
@@ -1585,6 +1640,7 @@ __init static int tracer_alloc_buffers(void)
         void *array;
         struct page *page;
         int pages = 0;
+        int ret = -ENOMEM;
         int i;
 
         /* Allocate the first page for all buffers */
@@ -1650,6 +1706,9 @@ __init static int tracer_alloc_buffers(void)
         register_tracer(&no_tracer);
         current_trace = &no_tracer;
 
+        /* All seems OK, enable tracing */
+        tracing_disabled = 0;
+
         return 0;
 
  free_buffers:
@@ -1678,7 +1737,7 @@ __init static int tracer_alloc_buffers(void)
                 }
 #endif
         }
-        return -ENOMEM;
+        return ret;
 }
 
-device_initcall(tracer_alloc_buffers);
+fs_initcall(tracer_alloc_buffers);