Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

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

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index cbc6acb..9a0bc98 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -29,6 +29,9 @@ static struct timekeeper timekeeper;
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
 
+/* Flag for if there is a persistent clock on this platform */
+bool __read_mostly persistent_clock_exist = false;
+
 static inline void tk_normalize_xtime(struct timekeeper *tk)
 {
        while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
@@ -135,6 +138,20 @@ static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
 }
 
 /* Timekeeper helper functions. */
+
+#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
+u32 (*arch_gettimeoffset)(void);
+
+u32 get_arch_timeoffset(void)
+{
+       if (likely(arch_gettimeoffset))
+               return arch_gettimeoffset();
+       return 0;
+}
+#else
+static inline u32 get_arch_timeoffset(void) { return 0; }
+#endif
+
 static inline s64 timekeeping_get_ns(struct timekeeper *tk)
 {
        cycle_t cycle_now, cycle_delta;
@@ -151,8 +168,8 @@ static inline s64 timekeeping_get_ns(struct timekeeper *tk)
        nsec = cycle_delta * tk->mult + tk->xtime_nsec;
        nsec >>= tk->shift;
 
-       /* If arch requires, add in gettimeoffset() */
-       return nsec + arch_gettimeoffset();
+       /* If arch requires, add in get_arch_timeoffset() */
+       return nsec + get_arch_timeoffset();
 }
 
 static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
@@ -171,8 +188,8 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
        /* convert delta to nanoseconds. */
        nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
 
-       /* If arch requires, add in gettimeoffset() */
-       return nsec + arch_gettimeoffset();
+       /* If arch requires, add in get_arch_timeoffset() */
+       return nsec + get_arch_timeoffset();
 }
 
 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
@@ -254,8 +271,8 @@ static void timekeeping_forward_now(struct timekeeper *tk)
 
        tk->xtime_nsec += cycle_delta * tk->mult;
 
-       /* If arch requires, add in gettimeoffset() */
-       tk->xtime_nsec += (u64)arch_gettimeoffset() << tk->shift;
+       /* If arch requires, add in get_arch_timeoffset() */
+       tk->xtime_nsec += (u64)get_arch_timeoffset() << tk->shift;
 
        tk_normalize_xtime(tk);
 
@@ -264,19 +281,18 @@ static void timekeeping_forward_now(struct timekeeper *tk)
 }
 
 /**
- * getnstimeofday - Returns the time of day in a timespec
+ * __getnstimeofday - Returns the time of day in a timespec.
  * @ts:                pointer to the timespec to be set
  *
- * Returns the time of day in a timespec.
+ * Updates the time of day in the timespec.
+ * Returns 0 on success, or -ve when suspended (timespec will be undefined).
  */
-void getnstimeofday(struct timespec *ts)
+int __getnstimeofday(struct timespec *ts)
 {
        struct timekeeper *tk = &timekeeper;
        unsigned long seq;
        s64 nsecs = 0;
 
-       WARN_ON(timekeeping_suspended);
-
        do {
                seq = read_seqbegin(&tk->lock);
 
@@ -287,6 +303,26 @@ void getnstimeofday(struct timespec *ts)
 
        ts->tv_nsec = 0;
        timespec_add_ns(ts, nsecs);
+
+       /*
+        * Do not bail out early, in case there were callers still using
+        * the value, even in the face of the WARN_ON.
+        */
+       if (unlikely(timekeeping_suspended))
+               return -EAGAIN;
+       return 0;
+}
+EXPORT_SYMBOL(__getnstimeofday);
+
+/**
+ * getnstimeofday - Returns the time of day in a timespec.
+ * @ts:                pointer to the timespec to be set
+ *
+ * Returns the time of day in a timespec (WARN if suspended).
+ */
+void getnstimeofday(struct timespec *ts)
+{
+       WARN_ON(__getnstimeofday(ts));
 }
 EXPORT_SYMBOL(getnstimeofday);
 
@@ -640,12 +676,14 @@ void __init timekeeping_init(void)
        struct timespec now, boot, tmp;
 
        read_persistent_clock(&now);
+
        if (!timespec_valid_strict(&now)) {
                pr_warn("WARNING: Persistent clock returned invalid value!\n"
                        "         Check your CMOS/BIOS settings.\n");
                now.tv_sec = 0;
                now.tv_nsec = 0;
-       }
+       } else if (now.tv_sec || now.tv_nsec)
+               persistent_clock_exist = true;
 
        read_boot_clock(&boot);
        if (!timespec_valid_strict(&boot)) {
@@ -718,11 +756,12 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
 {
        struct timekeeper *tk = &timekeeper;
        unsigned long flags;
-       struct timespec ts;
 
-       /* Make sure we don't set the clock twice */
-       read_persistent_clock(&ts);
-       if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
+       /*
+        * Make sure we don't set the clock twice, as timekeeping_resume()
+        * already did it
+        */
+       if (has_persistent_clock())
                return;
 
        write_seqlock_irqsave(&tk->lock, flags);