[PATCH] select: fix returned timeval
With David Woodhouse <dwmw2@infradead.org>
select() presently has a habit of increasing the value of the user's
`timeout' argument on return.
We were writing back a timeout larger than the original. We _deliberately_
round up, since we know we must wait at _least_ as long as the caller asks
us to.
The patch adds a couple of helper functions for magnitude comparison of
timespecs and of timevals, and uses them to prevent the various poll and
select functions from returning a timeout which is larger than the one which
was passed in.
The patch also fixes a bug in compat_sys_pselect7(): it was adding the new
timeout value to the old one and was returning that. It should just return
the new timeout value.
(We have various handy timespec/timeval-to-from-nsec conversion functions in
time.h. But this code open-codes it all).
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andi Kleen <ak@muc.de>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: george anzinger <george@mvista.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/time.h b/include/linux/time.h
index 7b4dc365..d9cdba5 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -33,11 +33,34 @@
#define NSEC_PER_SEC 1000000000L
#define NSEC_PER_USEC 1000L
-static __inline__ int timespec_equal(struct timespec *a, struct timespec *b)
+static inline int timespec_equal(struct timespec *a, struct timespec *b)
{
return (a->tv_sec == b->tv_sec) && (a->tv_nsec == b->tv_nsec);
}
+/*
+ * lhs < rhs: return <0
+ * lhs == rhs: return 0
+ * lhs > rhs: return >0
+ */
+static inline int timespec_compare(struct timespec *lhs, struct timespec *rhs)
+{
+ if (lhs->tv_sec < rhs->tv_sec)
+ return -1;
+ if (lhs->tv_sec > rhs->tv_sec)
+ return 1;
+ return lhs->tv_nsec - rhs->tv_nsec;
+}
+
+static inline int timeval_compare(struct timeval *lhs, struct timeval *rhs)
+{
+ if (lhs->tv_sec < rhs->tv_sec)
+ return -1;
+ if (lhs->tv_sec > rhs->tv_sec)
+ return 1;
+ return lhs->tv_usec - rhs->tv_usec;
+}
+
extern unsigned long mktime(const unsigned int year, const unsigned int mon,
const unsigned int day, const unsigned int hour,
const unsigned int min, const unsigned int sec);
