timerfd: new timerfd API

This is the new timerfd API as it is implemented by the following patch:

int timerfd_create(int clockid, int flags);
int timerfd_settime(int ufd, int flags,
		    const struct itimerspec *utmr,
		    struct itimerspec *otmr);
int timerfd_gettime(int ufd, struct itimerspec *otmr);

The timerfd_create() API creates an un-programmed timerfd fd.  The "clockid"
parameter can be either CLOCK_MONOTONIC or CLOCK_REALTIME.

The timerfd_settime() API give new settings by the timerfd fd, by optionally
retrieving the previous expiration time (in case the "otmr" parameter is not
NULL).

The time value specified in "utmr" is absolute, if the TFD_TIMER_ABSTIME bit
is set in the "flags" parameter.  Otherwise it's a relative time.

The timerfd_gettime() API returns the next expiration time of the timer, or
{0, 0} if the timerfd has not been set yet.

Like the previous timerfd API implementation, read(2) and poll(2) are
supported (with the same interface).  Here's a simple test program I used to
exercise the new timerfd APIs:

http://www.xmailserver.org/timerfd-test2.c

[akpm@linux-foundation.org: coding-style cleanups]
[akpm@linux-foundation.org: fix ia64 build]
[akpm@linux-foundation.org: fix m68k build]
[akpm@linux-foundation.org: fix mips build]
[akpm@linux-foundation.org: fix alpha, arm, blackfin, cris, m68k, s390, sparc and sparc64 builds]
[heiko.carstens@de.ibm.com: fix s390]
[akpm@linux-foundation.org: fix powerpc build]
[akpm@linux-foundation.org: fix sparc64 more]
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 1069998fe25f..668f3967eb39 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -306,7 +306,7 @@ EXPORT_SYMBOL_GPL(ktime_sub_ns);
 /*
  * Divide a ktime value by a nanosecond value
  */
-unsigned long ktime_divns(const ktime_t kt, s64 div)
+u64 ktime_divns(const ktime_t kt, s64 div)
 {
         u64 dclc, inc, dns;
         int sft = 0;
@@ -321,7 +321,7 @@ unsigned long ktime_divns(const ktime_t kt, s64 div)
         dclc >>= sft;
         do_div(dclc, (unsigned long) div);
 
-        return (unsigned long) dclc;
+        return dclc;
 }
 #endif /* BITS_PER_LONG >= 64 */
 
@@ -656,10 +656,9 @@ void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
  * Forward the timer expiry so it will expire in the future.
  * Returns the number of overruns.
  */
-unsigned long
-hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
+u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
 {
-        unsigned long orun = 1;
+        u64 orun = 1;
         ktime_t delta;
 
         delta = ktime_sub(now, timer->expires);