convert a few do_div users

This converts a few users of do_div to div_[su]64 and this demonstrates nicely
how it can reduce some expressions to one-liners.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 20 deletions

diff --git a/kernel/time.c b/kernel/time.c
index 86729042e4cd..343e2515375a 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -36,6 +36,7 @@
 #include <linux/security.h>
 #include <linux/fs.h>
 #include <linux/slab.h>
+#include <linux/math64.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -587,9 +588,7 @@ clock_t jiffies_to_clock_t(long x)
         return x / (HZ / USER_HZ);
 # endif
 #else
-        u64 tmp = (u64)x * TICK_NSEC;
-        do_div(tmp, (NSEC_PER_SEC / USER_HZ));
-        return (long)tmp;
+        return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(jiffies_to_clock_t);
@@ -601,16 +600,12 @@ unsigned long clock_t_to_jiffies(unsigned long x)
                 return ~0UL;
         return x * (HZ / USER_HZ);
 #else
-        u64 jif;
-
         /* Don't worry about loss of precision here .. */
         if (x >= ~0UL / HZ * USER_HZ)
                 return ~0UL;
 
         /* .. but do try to contain it here */
-        jif = x * (u64) HZ;
-        do_div(jif, USER_HZ);
-        return jif;
+        return div_u64((u64)x * HZ, USER_HZ);
 #endif
 }
 EXPORT_SYMBOL(clock_t_to_jiffies);
@@ -619,10 +614,9 @@ u64 jiffies_64_to_clock_t(u64 x)
 {
 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
 # if HZ < USER_HZ
-        x *= USER_HZ;
-        do_div(x, HZ);
+        x = div_u64(x * USER_HZ, HZ);
 # elif HZ > USER_HZ
-        do_div(x, HZ / USER_HZ);
+        x = div_u64(x, HZ / USER_HZ);
 # else
         /* Nothing to do */
 # endif
@@ -632,8 +626,7 @@ u64 jiffies_64_to_clock_t(u64 x)
          * but even this doesn't overflow in hundreds of years
          * in 64 bits, so..
          */
-        x *= TICK_NSEC;
-        do_div(x, (NSEC_PER_SEC / USER_HZ));
+        x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ));
 #endif
         return x;
 }
@@ -642,21 +635,17 @@ EXPORT_SYMBOL(jiffies_64_to_clock_t);
 u64 nsec_to_clock_t(u64 x)
 {
 #if (NSEC_PER_SEC % USER_HZ) == 0
-        do_div(x, (NSEC_PER_SEC / USER_HZ));
+        return div_u64(x, NSEC_PER_SEC / USER_HZ);
 #elif (USER_HZ % 512) == 0
-        x *= USER_HZ/512;
-        do_div(x, (NSEC_PER_SEC / 512));
+        return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
 #else
         /*
          * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
          * overflow after 64.99 years.
          * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
          */
-        x *= 9;
-        do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
-                                  USER_HZ));
+        return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
 #endif
-        return x;
 }
 
 #if (BITS_PER_LONG < 64)