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, 5 insertions, 4 deletions

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 36d563fd9e3b..122d5c787fe2 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -256,8 +256,9 @@ static void schedule_next_timer(struct k_itimer *timr)
         if (timr->it.real.interval.tv64 == 0)
                 return;
 
-        timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(),
-                                            timr->it.real.interval);
+        timr->it_overrun += (unsigned int) hrtimer_forward(timer,
+                                                timer->base->get_time(),
+                                                timr->it.real.interval);
 
         timr->it_overrun_last = timr->it_overrun;
         timr->it_overrun = -1;
@@ -386,7 +387,7 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
                                         now = ktime_add(now, kj);
                         }
 #endif
-                        timr->it_overrun +=
+                        timr->it_overrun += (unsigned int)
                                 hrtimer_forward(timer, now,
                                                 timr->it.real.interval);
                         ret = HRTIMER_RESTART;
@@ -662,7 +663,7 @@ common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting)
          */
         if (iv.tv64 && (timr->it_requeue_pending & REQUEUE_PENDING ||
             (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE))
-                timr->it_overrun += hrtimer_forward(timer, now, iv);
+                timr->it_overrun += (unsigned int) hrtimer_forward(timer, now, iv);
 
         remaining = ktime_sub(timer->expires, now);
         /* Return 0 only, when the timer is expired and not pending */