time: Prevent early expiry of hrtimers[CLOCK_REALTIME] at the leap second edge

[cascardo/linux.git] / kernel / time / ntp.c

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 7a68100..033743e 100644 (file)
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -35,6 +35,7 @@ unsigned long                 tick_nsec;
 static u64                     tick_length;
 static u64                     tick_length_base;
 
+#define SECS_PER_DAY           86400
 #define MAX_TICKADJ            500LL           /* usecs */
 #define MAX_TICKADJ_SCALED \
        (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
@@ -76,6 +77,9 @@ static long                   time_adjust;
 /* constant (boot-param configurable) NTP tick adjustment (upscaled)   */
 static s64                     ntp_tick_adj;
 
+/* second value of the next pending leapsecond, or TIME64_MAX if no leap */
+static time64_t                        ntp_next_leap_sec = TIME64_MAX;
+
 #ifdef CONFIG_NTP_PPS
 
 /*
@@ -349,6 +353,7 @@ void ntp_clear(void)
        tick_length     = tick_length_base;
        time_offset     = 0;
 
+       ntp_next_leap_sec = TIME64_MAX;
        /* Clear PPS state variables */
        pps_clear();
 }
@@ -359,6 +364,21 @@ u64 ntp_tick_length(void)
        return tick_length;
 }
 
+/**
+ * ntp_get_next_leap - Returns the next leapsecond in CLOCK_REALTIME ktime_t
+ *
+ * Provides the time of the next leapsecond against CLOCK_REALTIME in
+ * a ktime_t format. Returns KTIME_MAX if no leapsecond is pending.
+ */
+ktime_t ntp_get_next_leap(void)
+{
+       ktime_t ret;
+
+       if ((time_state == TIME_INS) && (time_status & STA_INS))
+               return ktime_set(ntp_next_leap_sec, 0);
+       ret.tv64 = KTIME_MAX;
+       return ret;
+}
 
 /*
  * this routine handles the overflow of the microsecond field
@@ -382,15 +402,21 @@ int second_overflow(unsigned long secs)
         */
        switch (time_state) {
        case TIME_OK:
-               if (time_status & STA_INS)
+               if (time_status & STA_INS) {
                        time_state = TIME_INS;
-               else if (time_status & STA_DEL)
+                       ntp_next_leap_sec = secs + SECS_PER_DAY -
+                                               (secs % SECS_PER_DAY);
+               } else if (time_status & STA_DEL) {
                        time_state = TIME_DEL;
+                       ntp_next_leap_sec = secs + SECS_PER_DAY -
+                                                ((secs+1) % SECS_PER_DAY);
+               }
                break;
        case TIME_INS:
-               if (!(time_status & STA_INS))
+               if (!(time_status & STA_INS)) {
+                       ntp_next_leap_sec = TIME64_MAX;
                        time_state = TIME_OK;
-               else if (secs % 86400 == 0) {
+               } else if (secs % SECS_PER_DAY == 0) {
                        leap = -1;
                        time_state = TIME_OOP;
                        printk(KERN_NOTICE
@@ -398,19 +424,21 @@ int second_overflow(unsigned long secs)
                }
                break;
        case TIME_DEL:
-               if (!(time_status & STA_DEL))
+               if (!(time_status & STA_DEL)) {
+                       ntp_next_leap_sec = TIME64_MAX;
                        time_state = TIME_OK;
-               else if ((secs + 1) % 86400 == 0) {
+               } else if ((secs + 1) % SECS_PER_DAY == 0) {
                        leap = 1;
+                       ntp_next_leap_sec = TIME64_MAX;
                        time_state = TIME_WAIT;
                        printk(KERN_NOTICE
                                "Clock: deleting leap second 23:59:59 UTC\n");
                }
                break;
        case TIME_OOP:
+               ntp_next_leap_sec = TIME64_MAX;
                time_state = TIME_WAIT;
                break;
-
        case TIME_WAIT:
                if (!(time_status & (STA_INS | STA_DEL)))
                        time_state = TIME_OK;
@@ -547,6 +575,7 @@ static inline void process_adj_status(struct timex *txc, struct timespec64 *ts)
        if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
                time_state = TIME_OK;
                time_status = STA_UNSYNC;
+               ntp_next_leap_sec = TIME64_MAX;
                /* restart PPS frequency calibration */
                pps_reset_freq_interval();
        }