2 files changed, 29 insertions, 12 deletions

diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index 5fc3d1083071..2b6a204bd8d4 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -166,19 +166,34 @@ static inline bool ktime_before(const ktime_t cmp1, const ktime_t cmp2)
 }
 
 #if BITS_PER_LONG < 64
-extern u64 __ktime_divns(const ktime_t kt, s64 div);
-static inline u64 ktime_divns(const ktime_t kt, s64 div)
+extern s64 __ktime_divns(const ktime_t kt, s64 div);
+static inline s64 ktime_divns(const ktime_t kt, s64 div)
 {
+        /*
+         * Negative divisors could cause an inf loop,
+         * so bug out here.
+         */
+        BUG_ON(div < 0);
         if (__builtin_constant_p(div) && !(div >> 32)) {
-                u64 ns = kt.tv64;
-                do_div(ns, div);
-                return ns;
+                s64 ns = kt.tv64;
+                u64 tmp = ns < 0 ? -ns : ns;
+
+                do_div(tmp, div);
+                return ns < 0 ? -tmp : tmp;
         } else {
                 return __ktime_divns(kt, div);
         }
 }
 #else /* BITS_PER_LONG < 64 */
-# define ktime_divns(kt, div)           (u64)((kt).tv64 / (div))
+static inline s64 ktime_divns(const ktime_t kt, s64 div)
+{
+        /*
+         * 32-bit implementation cannot handle negative divisors,
+         * so catch them on 64bit as well.
+         */
+        WARN_ON(div < 0);
+        return kt.tv64 / div;
+}
 #endif
 
 static inline s64 ktime_to_us(const ktime_t kt)
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 76d4bd962b19..93ef7190bdea 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -266,21 +266,23 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 /*
  * Divide a ktime value by a nanosecond value
  */
-u64 __ktime_divns(const ktime_t kt, s64 div)
+s64 __ktime_divns(const ktime_t kt, s64 div)
 {
-        u64 dclc;
         int sft = 0;
+        s64 dclc;
+        u64 tmp;
 
         dclc = ktime_to_ns(kt);
+        tmp = dclc < 0 ? -dclc : dclc;
+
         /* Make sure the divisor is less than 2^32: */
         while (div >> 32) {
                 sft++;
                 div >>= 1;
         }
-        dclc >>= sft;
-        do_div(dclc, (unsigned long) div);
-
-        return dclc;
+        tmp >>= sft;
+        do_div(tmp, (unsigned long) div);
+        return dclc < 0 ? -tmp : tmp;
 }
 EXPORT_SYMBOL_GPL(__ktime_divns);
 #endif /* BITS_PER_LONG >= 64 */