Re: [PATCH] prevent timespec/timeval to ktime_t overflow

Thomas Gleixner
2006-09-02T19:24:30Z

On Sat, 2006-09-02 at 20:41 +0200, Thomas Gleixner wrote:
> This smells like gcc magic. Can you please disassemble the code in
> question ?

Doh.

Fortunately I own shares of a brown-paperbag-factory and the dividend is
payed in kind.

> > I wonder if this is related to the occasional hrtimr_run_queues() lockup
> > which Andi is encountering.
>
> Hmm, not sure.

I'm quite sure right now.

tglx

diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index ed3396d..84eeecd 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -56,7 +56,8 @@ typedef union {
#endif
} ktime_t;

-#define KTIME_MAX (~((u64)1 << 63))
+#define KTIME_MAX ((s64)~((u64)1 << 63))
+#define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)

/*
* ktime_t definitions when using the 64-bit scalar representation:
@@ -73,6 +74,10 @@ typedef union {
*/
static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
{
+#if (BITS_PER_LONG == 64)
+ if (unlikely(secs >= KTIME_SEC_MAX))
+ return (ktime_t){ .tv64 = KTIME_MAX };
+#endif
return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs };
}

--
VGER BF report: U 0.482714