posix-timers: Introduce a syscall for clock tuning.

A new syscall is introduced that allows tuning of a POSIX clock. The
new call, clock_adjtime, takes two parameters, the clock ID and a
pointer to a struct timex. Any ADJTIMEX(2) operation may be requested
via this system call, but various POSIX clocks may or may not support
tuning.

[ tglx: Adapted to the posix-timer cleanup series. Avoid copy_to_user
  	in the error case ]

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Acked-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <20110201134419.869804645@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 23 insertions, 0 deletions

diff --git a/kernel/compat.c b/kernel/compat.c
index 449e853cf41d..38b1d2c1cbe8 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -675,6 +675,29 @@ long compat_sys_clock_gettime(clockid_t which_clock,
         return err;
 }
 
+long compat_sys_clock_adjtime(clockid_t which_clock,
+                struct compat_timex __user *utp)
+{
+        struct timex txc;
+        mm_segment_t oldfs;
+        int err, ret;
+
+        err = compat_get_timex(&txc, utp);
+        if (err)
+                return err;
+
+        oldfs = get_fs();
+        set_fs(KERNEL_DS);
+        ret = sys_clock_adjtime(which_clock, (struct timex __user *) &txc);
+        set_fs(oldfs);
+
+        err = compat_put_timex(utp, &txc);
+        if (err)
+                return err;
+
+        return ret;
+}
+
 long compat_sys_clock_getres(clockid_t which_clock,
                 struct compat_timespec __user *tp)
 {