The comment for timespec_diff_us() claims it will wrap after 2^64µs. This
is incorrect for two reasons:
* It returns a long long, which is probably 64-bits, but might not be
* It returns a signed value, so even if it is 64 bits it will wrap after
2^63µs
Correct the comment and use an explicitly 64-bit type to avoid that
imprecision.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
util.c | 4 ++--
util.h | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/util.c b/util.c
index f2e26a7a..0cc908a5 100644
--- a/util.c
+++ b/util.c
@@ -244,9 +244,9 @@ void sock_probe_mem(struct ctx *c)
* @a: Minuend timestamp
* @b: Subtrahend timestamp
*
- * Return: difference in microseconds (wraps after 2^64 / 10^6s ~= 585k years)
+ * Return: difference in microseconds (wraps after 2^63 / 10^6s ~= 292k years)
*/
-long long timespec_diff_us(const struct timespec *a, const struct timespec *b)
+int64_t timespec_diff_us(const struct timespec *a, const struct timespec *b)
{
if (a->tv_nsec < b->tv_nsec) {
return (b->tv_nsec - a->tv_nsec) / 1000 +
diff --git a/util.h b/util.h
index b7541ce2..d0fec7b3 100644
--- a/util.h
+++ b/util.h
@@ -168,7 +168,7 @@ int sock_l4(const struct ctx *c, sa_family_t af, enum epoll_type
type,
uint32_t data);
void sock_probe_mem(struct ctx *c);
long timespec_diff_ms(const struct timespec *a, const struct timespec *b);
-long long timespec_diff_us(const struct timespec *a, const struct timespec *b);
+int64_t timespec_diff_us(const struct timespec *a, const struct timespec *b);
void bitmap_set(uint8_t *map, unsigned bit);
void bitmap_clear(uint8_t *map, unsigned bit);
bool bitmap_isset(const uint8_t *map, unsigned bit);
--
2.45.2