sched: improve sched_clock() performance

[linux-2.6-omap-h63xx.git] / kernel / time.c

diff --git a/kernel/time.c b/kernel/time.c
index cbe0d5a222ff8727286701b90099528a533cfc73..d63a4336fad69c85f007788a7932959595f0cb73 100644 (file)
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -246,7 +246,7 @@ unsigned int inline jiffies_to_msecs(const unsigned long j)
        return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
 #else
 # if BITS_PER_LONG == 32
-       return ((u64)HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32;
+       return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32;
 # else
        return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN;
 # endif
@@ -262,7 +262,7 @@ unsigned int inline jiffies_to_usecs(const unsigned long j)
        return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
 #else
 # if BITS_PER_LONG == 32
-       return ((u64)HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
+       return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
 # else
        return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
 # endif
@@ -476,7 +476,7 @@ unsigned long msecs_to_jiffies(const unsigned int m)
        if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
                return MAX_JIFFY_OFFSET;
 
-       return ((u64)MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32)
+       return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32)
                >> MSEC_TO_HZ_SHR32;
 #endif
 }
@@ -491,7 +491,7 @@ unsigned long usecs_to_jiffies(const unsigned int u)
 #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
        return u * (HZ / USEC_PER_SEC);
 #else
-       return ((u64)USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
+       return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
                >> USEC_TO_HZ_SHR32;
 #endif
 }
@@ -669,3 +669,21 @@ EXPORT_SYMBOL(get_jiffies_64);
 #endif
 
 EXPORT_SYMBOL(jiffies);
+
+/*
+ * Add two timespec values and do a safety check for overflow.
+ * It's assumed that both values are valid (>= 0)
+ */
+struct timespec timespec_add_safe(const struct timespec lhs,
+                                 const struct timespec rhs)
+{
+       struct timespec res;
+
+       set_normalized_timespec(&res, lhs.tv_sec + rhs.tv_sec,
+                               lhs.tv_nsec + rhs.tv_nsec);
+
+       if (res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)
+               res.tv_sec = TIME_T_MAX;
+
+       return res;
+}