nohz: Fix stale jiffies update in tick_nohz_restart()

[linux-flexiantxendom0-3.2.10.git] / kernel / time.c

diff --git a/kernel/time.c b/kernel/time.c
index 2e2e469..ba744cf 100644 (file)
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -27,7 +27,7 @@
  *     with nanosecond accuracy
  */
 
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/timex.h>
 #include <linux/capability.h>
 #include <linux/clocksource.h>
@@ -35,7 +35,6 @@
 #include <linux/syscalls.h>
 #include <linux/security.h>
 #include <linux/fs.h>
-#include <linux/slab.h>
 #include <linux/math64.h>
 #include <linux/ptrace.h>
 
@@ -133,12 +132,11 @@ SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv,
  */
 static inline void warp_clock(void)
 {
-       write_seqlock_irq(&xtime_lock);
-       wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
-       xtime.tv_sec += sys_tz.tz_minuteswest * 60;
-       update_xtime_cache(0);
-       write_sequnlock_irq(&xtime_lock);
-       clock_was_set();
+       struct timespec adjust;
+
+       adjust = current_kernel_time();
+       adjust.tv_sec += sys_tz.tz_minuteswest * 60;
+       do_settimeofday(&adjust);
 }
 
 /*
@@ -152,7 +150,7 @@ static inline void warp_clock(void)
  * various programs will get confused when the clock gets warped.
  */
 
-int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
+int do_sys_settimeofday(const struct timespec *tv, const struct timezone *tz)
 {
        static int firsttime = 1;
        int error = 0;
@@ -165,7 +163,6 @@ int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
                return error;
 
        if (tz) {
-               /* SMP safe, global irq locking makes it work. */
                sys_tz = *tz;
                update_vsyscall_tz();
                if (firsttime) {
@@ -175,12 +172,7 @@ int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
                }
        }
        if (tv)
-       {
-               /* SMP safe, again the code in arch/foo/time.c should
-                * globally block out interrupts when it runs.
-                */
                return do_settimeofday(tv);
-       }
        return 0;
 }
 
@@ -240,7 +232,7 @@ EXPORT_SYMBOL(current_fs_time);
  * Avoid unnecessary multiplications/divisions in the
  * two most common HZ cases:
  */
-unsigned int inline jiffies_to_msecs(const unsigned long j)
+inline unsigned int jiffies_to_msecs(const unsigned long j)
 {
 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
        return (MSEC_PER_SEC / HZ) * j;
@@ -256,7 +248,7 @@ unsigned int inline jiffies_to_msecs(const unsigned long j)
 }
 EXPORT_SYMBOL(jiffies_to_msecs);
 
-unsigned int inline jiffies_to_usecs(const unsigned long j)
+inline unsigned int jiffies_to_usecs(const unsigned long j)
 {
 #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
        return (USEC_PER_SEC / HZ) * j;
@@ -302,22 +294,6 @@ struct timespec timespec_trunc(struct timespec t, unsigned gran)
 }
 EXPORT_SYMBOL(timespec_trunc);
 
-#ifndef CONFIG_GENERIC_TIME
-/*
- * Simulate gettimeofday using do_gettimeofday which only allows a timeval
- * and therefore only yields usec accuracy
- */
-void getnstimeofday(struct timespec *tv)
-{
-       struct timeval x;
-
-       do_gettimeofday(&x);
-       tv->tv_sec = x.tv_sec;
-       tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
-}
-EXPORT_SYMBOL_GPL(getnstimeofday);
-#endif
-
 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
  * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
@@ -593,7 +569,7 @@ EXPORT_SYMBOL(jiffies_to_timeval);
 /*
  * Convert jiffies/jiffies_64 to clock_t and back.
  */
-clock_t jiffies_to_clock_t(long x)
+clock_t jiffies_to_clock_t(unsigned long x)
 {
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
 # if HZ < USER_HZ
@@ -662,22 +638,53 @@ u64 nsec_to_clock_t(u64 x)
 #endif
 }
 
-#if (BITS_PER_LONG < 64)
-u64 get_jiffies_64(void)
+/**
+ * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
+ *
+ * @n: nsecs in u64
+ *
+ * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
+ * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
+ * for scheduler, not for use in device drivers to calculate timeout value.
+ *
+ * note:
+ *   NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
+ *   ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
+ */
+u64 nsecs_to_jiffies64(u64 n)
 {
-       unsigned long seq;
-       u64 ret;
-
-       do {
-               seq = read_seqbegin(&xtime_lock);
-               ret = jiffies_64;
-       } while (read_seqretry(&xtime_lock, seq));
-       return ret;
-}
-EXPORT_SYMBOL(get_jiffies_64);
+#if (NSEC_PER_SEC % HZ) == 0
+       /* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */
+       return div_u64(n, NSEC_PER_SEC / HZ);
+#elif (HZ % 512) == 0
+       /* overflow after 292 years if HZ = 1024 */
+       return div_u64(n * HZ / 512, NSEC_PER_SEC / 512);
+#else
+       /*
+        * Generic case - optimized for cases where HZ is a multiple of 3.
+        * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc.
+        */
+       return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ);
 #endif
+}
 
-EXPORT_SYMBOL(jiffies);
+/**
+ * nsecs_to_jiffies - Convert nsecs in u64 to jiffies
+ *
+ * @n: nsecs in u64
+ *
+ * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
+ * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
+ * for scheduler, not for use in device drivers to calculate timeout value.
+ *
+ * note:
+ *   NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
+ *   ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
+ */
+unsigned long nsecs_to_jiffies(u64 n)
+{
+       return (unsigned long)nsecs_to_jiffies64(n);
+}
 
 /*
  * Add two timespec values and do a safety check for overflow.