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

From: "Steven Rostedt (VMware)" <rostedt@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) <rostedt@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;
--
2.13.6
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