[PATCH] sys_alarm() unsigned signed conversion fixup

[linux-2.6-block.git] / kernel / itimer.c

diff --git a/kernel/itimer.c b/kernel/itimer.c
index 379be2f8c84c33445b9cea549fe2c7215d3d6cc4..a2dc375927d82dca90aadc91cc1696a0b057234c 100644 (file)
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -226,6 +226,43 @@ again:
        return 0;
 }
 
+/**
+ * alarm_setitimer - set alarm in seconds
+ *
+ * @seconds:   number of seconds until alarm
+ *             0 disables the alarm
+ *
+ * Returns the remaining time in seconds of a pending timer or 0 when
+ * the timer is not active.
+ *
+ * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
+ * negative timeval settings which would cause immediate expiry.
+ */
+unsigned int alarm_setitimer(unsigned int seconds)
+{
+       struct itimerval it_new, it_old;
+
+#if BITS_PER_LONG < 64
+       if (seconds > INT_MAX)
+               seconds = INT_MAX;
+#endif
+       it_new.it_value.tv_sec = seconds;
+       it_new.it_value.tv_usec = 0;
+       it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
+
+       do_setitimer(ITIMER_REAL, &it_new, &it_old);
+
+       /*
+        * We can't return 0 if we have an alarm pending ...  And we'd
+        * better return too much than too little anyway
+        */
+       if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
+             it_old.it_value.tv_usec >= 500000)
+               it_old.it_value.tv_sec++;
+
+       return it_old.it_value.tv_sec;
+}
+
 asmlinkage long sys_setitimer(int which,
                              struct itimerval __user *value,
                              struct itimerval __user *ovalue)