time: Rework debugging variables so they aren't global

Ingo suggested that the timekeeping debugging variables
recently added should not be global, and should be tied
to the timekeeper's read_base.

Thus this patch implements that suggestion.

This version is different from the earlier versions
as it keeps the variables in the timekeeper structure
rather then in the tkr.

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h
index 6f8276a..e1f5a11 100644 (file)
--- a/include/linux/timekeeper_internal.h
+++ b/include/linux/timekeeper_internal.h
@@ -61,6 +61,9 @@ struct tk_read_base {
  *                     shifted nano seconds.
  * @ntp_error_shift:   Shift conversion between clock shifted nano seconds and
  *                     ntp shifted nano seconds.
+ * @last_warning:      Warning ratelimiter (DEBUG_TIMEKEEPING)
+ * @underflow_seen:    Underflow warning flag (DEBUG_TIMEKEEPING)
+ * @overflow_seen:     Overflow warning flag (DEBUG_TIMEKEEPING)
  *
  * Note: For timespec(64) based interfaces wall_to_monotonic is what
  * we need to add to xtime (or xtime corrected for sub jiffie times)
@@ -106,6 +109,18 @@ struct timekeeper {
        s64                     ntp_error;
        u32                     ntp_error_shift;
        u32                     ntp_err_mult;
+#ifdef CONFIG_DEBUG_TIMEKEEPING
+       long                    last_warning;
+       /*
+        * These simple flag variables are managed
+        * without locks, which is racy, but they are
+        * ok since we don't really care about being
+        * super precise about how many events were
+        * seen, just that a problem was observed.
+        */
+       int                     underflow_seen;
+       int                     overflow_seen;
+#endif
 };
 
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 85d3763..2f10b65 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -118,18 +118,6 @@ static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
 
 #ifdef CONFIG_DEBUG_TIMEKEEPING
 #define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
-/*
- * These simple flag variables are managed
- * without locks, which is racy, but ok since
- * we don't really care about being super
- * precise about how many events were seen,
- * just that a problem was observed.
- */
-static int timekeeping_underflow_seen;
-static int timekeeping_overflow_seen;
-
-/* last_warning is only modified under the timekeeping lock */
-static long timekeeping_last_warning;
 
 static void timekeeping_check_update(struct timekeeper *tk, cycle_t offset)
 {
@@ -149,29 +137,30 @@ static void timekeeping_check_update(struct timekeeper *tk, cycle_t offset)
                }
        }
 
-       if (timekeeping_underflow_seen) {
-               if (jiffies - timekeeping_last_warning > WARNING_FREQ) {
+       if (tk->underflow_seen) {
+               if (jiffies - tk->last_warning > WARNING_FREQ) {
                        printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
                        printk_deferred("         Please report this, consider using a different clocksource, if possible.\n");
                        printk_deferred("         Your kernel is probably still fine.\n");
-                       timekeeping_last_warning = jiffies;
+                       tk->last_warning = jiffies;
                }
-               timekeeping_underflow_seen = 0;
+               tk->underflow_seen = 0;
        }
 
-       if (timekeeping_overflow_seen) {
-               if (jiffies - timekeeping_last_warning > WARNING_FREQ) {
+       if (tk->overflow_seen) {
+               if (jiffies - tk->last_warning > WARNING_FREQ) {
                        printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
                        printk_deferred("         Please report this, consider using a different clocksource, if possible.\n");
                        printk_deferred("         Your kernel is probably still fine.\n");
-                       timekeeping_last_warning = jiffies;
+                       tk->last_warning = jiffies;
                }
-               timekeeping_overflow_seen = 0;
+               tk->overflow_seen = 0;
        }
 }
 
 static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
 {
+       struct timekeeper *tk = &tk_core.timekeeper;
        cycle_t now, last, mask, max, delta;
        unsigned int seq;
 
@@ -197,13 +186,13 @@ static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
         * mask-relative negative values.
         */
        if (unlikely((~delta & mask) < (mask >> 3))) {
-               timekeeping_underflow_seen = 1;
+               tk->underflow_seen = 1;
                delta = 0;
        }
 
        /* Cap delta value to the max_cycles values to avoid mult overflows */
        if (unlikely(delta > max)) {
-               timekeeping_overflow_seen = 1;
+               tk->overflow_seen = 1;
                delta = tkr->clock->max_cycles;
        }