Since kernel 2.6.22, Linux setitimer() now conforms to POSIX.1,

giving an EINVAL error for a non-canonical tv_usec value.

man2/getitimer.2

@@ -130,7 +130,10 @@ is not one of
 .BR ITIMER_REAL ,
 .BR ITIMER_VIRTUAL ,
 or
-.BR ITIMER_PROF .
+.BR ITIMER_PROF ;
+or (since kernel 2.6.22) one of the
+.I tv_usec
+fields contains a value outside the range 0 to 999999.
 .SH "CONFORMING TO"
 POSIX.1-2001, SVr4, 4.4BSD (this call first appeared in 4.2BSD).
 .SH NOTES
@@ -173,24 +176,19 @@ POSIX.1-2001 says that
 should fail if a
 .I tv_usec
 value is specified that is outside of the range 0 to 999999.
-However, Linux does not give an error, but instead silently
+However, in kernels up to and including 2.6.21,
+Linux does not give an error, but instead silently
 adjusts the corresponding seconds value for the timer.
-In the future (scheduled for March 2007),
-this non-conformance will be repaired:
-existing applications should be fixed now to ensure that they supply
-a properly formed
+From kernel 2.6.22 onwards,
+this non-conformance has been repaired:
+an improper
 .I tv_usec
-value.
-.\" FIXME . Bugzilla report 25 Apr 2006:
+value results in an
+.B EINVAL
+error.
+.\" Bugzilla report 25 Apr 2006:
 .\" http://bugzilla.kernel.org/show_bug.cgi?id=6443
 .\" "setitimer() should reject non-canonical arguments"
-.\" The feedback on this report points to a kernel patch
-.\" which apparently should result in this problem
-.\" being fixed after a clean-up period of one year
-.\" (i.e., March 2007).
-.\" Not fixed as at 2.6.21, May 2007.
-.\" The fix is in as at 2.6.22-rc2 -- check whether it makes it to release
-.\" See the EINVAL error return from kernel/itimer.c::do_setitimer().
 .SH "SEE ALSO"
 .BR gettimeofday (2),
 .BR sigaction (2),