[PATCH] time: Fix adjustment cleanup bug in timekeeping_adjust()

[Ingo Molnar <mingo@kernel.org>]

* Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote:

> Hello.
> 
> Bisected to 2a8c0883 "time: Move xtime_nsec adjustment 
> underflow handling timekeeping_adjust".
> 
> Would you check?

probably caused by this stray return in timekeeping_adjust():

        } else
                return;

which should really be a proper goto - like the (totally 
untested!) patch below.

Does this fix the bug for you?

Thanks,

	Ingo

-------------

Subject: time: Fix adjustment cleanup bug in timekeeping_adjust()

Also make the flow more readable by properly balancing curly 
braces.

Signed-off-by: Ingo Molnar <mingo@kernel.org>


diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 2988bc8..e16af19 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -923,20 +923,22 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
 		if (likely(error <= interval))
 			adj = 1;
 		else
-			adj = timekeeping_bigadjust(tk, error, &interval,
-							&offset);
-	} else if (error < -interval) {
-		/* See comment above, this is just switched for the negative */
-		error >>= 2;
-		if (likely(error >= -interval)) {
-			adj = -1;
-			interval = -interval;
-			offset = -offset;
-		} else
-			adj = timekeeping_bigadjust(tk, error, &interval,
-							&offset);
-	} else
-		return;
+			adj = timekeeping_bigadjust(tk, error, &interval, &offset);
+	} else {
+		if (error < -interval) {
+			/* See comment above, this is just switched for the negative */
+			error >>= 2;
+			if (likely(error >= -interval)) {
+				adj = -1;
+				interval = -interval;
+				offset = -offset;
+			} else {
+				adj = timekeeping_bigadjust(tk, error, &interval, &offset);
+			}
+		} else {
+			goto out_adjust;
+		}
+	}
 
 	if (unlikely(tk->clock->maxadj &&
 		(tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) {
@@ -999,6 +1001,7 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
 	tk->xtime_nsec -= offset;
 	tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
 
+out_adjust:
 	/*
 	 * It may be possible that when we entered this function, xtime_nsec
 	 * was very small.  Further, if we're slightly speeding the clocksource