[for-next][PATCH 3/4] init, tracing: Have printk come through the trace events for initcall_debug

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rost...@goodmis.org>

With trace events set before and after the initcall function calls, instead
of having a separate routine for printing out the initcalls when
initcall_debug is specified on the kernel command line, have the code
register a callback to the tracepoints where the initcall trace events are.

This removes the need for having a separate function to do the initcalls as
the tracepoint callbacks can handle the printk. It also includes other
initcalls that are not called by the do_one_initcall() which includes
console and security initcalls.

Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
---
 init/main.c | 51 +++++++++++++++++++++++++++++++++++----------------
 1 file changed, 35 insertions(+), 16 deletions(-)

diff --git a/init/main.c b/init/main.c
index 2af8f2bb5ca8..589d1226016e 100644
--- a/init/main.c
+++ b/init/main.c
@@ -494,6 +494,10 @@ void __init __weak thread_stack_cache_init(void)
 
 void __init __weak mem_encrypt_init(void) { }
 
+bool initcall_debug;
+core_param(initcall_debug, initcall_debug, bool, 0644);
+static void __init initcall_debug_enable(void);
+
 /*
  * Set up kernel memory allocators
  */
@@ -615,6 +619,9 @@ asmlinkage __visible void __init start_kernel(void)
        /* Trace events are available after this */
        trace_init();
 
+       if (initcall_debug)
+               initcall_debug_enable();
+
        context_tracking_init();
        /* init some links before init_ISA_irqs() */
        early_irq_init();
@@ -731,9 +738,6 @@ static void __init do_ctors(void)
 #endif
 }
 
-bool initcall_debug;
-core_param(initcall_debug, initcall_debug, bool, 0644);
-
 #ifdef CONFIG_KALLSYMS
 struct blacklist_entry {
        struct list_head next;
@@ -803,38 +807,53 @@ static bool __init_or_module 
initcall_blacklisted(initcall_t fn)
 #endif
 __setup("initcall_blacklist=", initcall_blacklist);
 
-static int __init_or_module do_one_initcall_debug(initcall_t fn)
+static __init_or_module void
+trace_initcall_start_cb(void *data, initcall_t fn)
 {
-       ktime_t calltime, delta, rettime;
-       unsigned long long duration;
-       int ret;
+       ktime_t *calltime = (ktime_t *)data;
 
        printk(KERN_DEBUG "calling  %pF @ %i\n", fn, task_pid_nr(current));
-       calltime = ktime_get();
-       ret = fn();
+       *calltime = ktime_get();
+}
+
+static __init_or_module void
+trace_initcall_finish_cb(void *data, initcall_t fn, int ret)
+{
+       ktime_t *calltime = (ktime_t *)data;
+       ktime_t delta, rettime;
+       unsigned long long duration;
+
        rettime = ktime_get();
-       delta = ktime_sub(rettime, calltime);
+       delta = ktime_sub(rettime, *calltime);
        duration = (unsigned long long) ktime_to_ns(delta) >> 10;
        printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n",
                 fn, ret, duration);
+}
 
-       return ret;
+static ktime_t initcall_calltime;
+
+static void __init initcall_debug_enable(void)
+{
+       int ret;
+
+       ret = register_trace_initcall_start(trace_initcall_start_cb,
+                                           &initcall_calltime);
+       ret |= register_trace_initcall_finish(trace_initcall_finish_cb,
+                                             &initcall_calltime);
+       WARN(ret, "Failed to register initcall tracepoints\n");
 }
 
 int __init_or_module do_one_initcall(initcall_t fn)
 {
        int count = preempt_count();
-       int ret;
        char msgbuf[64];
+       int ret;
 
        if (initcall_blacklisted(fn))
                return -EPERM;
 
        trace_initcall_start(fn);
-       if (initcall_debug)
-               ret = do_one_initcall_debug(fn);
-       else
-               ret = fn();
+       ret = fn();
        trace_initcall_finish(fn, ret);
 
        msgbuf[0] = 0;
-- 
2.16.3