init: use ktime_us_delta() to make initcall_debug log more precise

Use ktime_us_delta() to make the initcall_debug log more precise than
right shifting the result of ktime_to_ns() by 10 bits.

Link: https://lkml.kernel.org/r/20220209053350.15771-1-mark-pk.tsai@mediatek.comSigned-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: YJ Chiang <yj.chiang@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

init/main.c

@@ -1246,15 +1246,11 @@ trace_initcall_start_cb(void *data, initcall_t fn)
 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;
+	ktime_t rettime, *calltime = (ktime_t *)data;
 
 	rettime = ktime_get();
-	delta = ktime_sub(rettime, *calltime);
-	duration = (unsigned long long) ktime_to_ns(delta) >> 10;
 	printk(KERN_DEBUG "initcall %pS returned %d after %lld usecs\n",
-		 fn, ret, duration);
+		 fn, ret, (unsigned long long)ktime_us_delta(rettime, *calltime));
 }
 
 static ktime_t initcall_calltime;