[PATCH 1/8] jiffies: Remove HZ > USEC_PER_SEC special case

[Frederic Weisbecker <fweisbec@gmail.com>]

HZ never goes much further 1000 and a bit. And if we ever reach one tick
per microsecond, we might be having a problem.

Lets stop maintaining this special case, just leave a paranoid check.

Cc: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc; John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/time/time.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/time/time.c b/kernel/time/time.c
index 972e3bb..6a22980 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -268,10 +268,14 @@ EXPORT_SYMBOL(jiffies_to_msecs);
 
 unsigned int jiffies_to_usecs(const unsigned long j)
 {
-#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
+	/*
+	 * Hz usually doesn't go much further MSEC_PER_SEC.
+	 * jiffies_to_usecs() and usecs_to_jiffies() depend on that.
+	 */
+	BUILD_BUG_ON(HZ > USEC_PER_SEC);
+
+#if !(USEC_PER_SEC % HZ)
 	return (USEC_PER_SEC / HZ) * j;
-#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
-	return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
 #else
 # if BITS_PER_LONG == 32
 	return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
@@ -526,10 +530,8 @@ unsigned long usecs_to_jiffies(const unsigned int u)
 {
 	if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
 		return MAX_JIFFY_OFFSET;
-#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
+#if !(USEC_PER_SEC % HZ)
 	return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
-#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
-	return u * (HZ / USEC_PER_SEC);
 #else
 	return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
 		>> USEC_TO_HZ_SHR32;
-- 
2.1.4