Change the return value of sema_timedwait() so it returns 0 on

success and a proper errno value on failure.  This makes it
consistent with cv_timedwait(), and paves the way for the
introduction of functions such as sema_timedwait_sig() which can
fail in multiple ways.

Bump __FreeBSD_version and add a note to UPDATING.

Approved by:	scottl (ips driver), arch

1 files changed, 17 insertions, 4 deletions

diff --git a/share/man/man9/sema.9 b/share/man/man9/sema.9
index 9ba5890..e8f2cb9 100644
--- a/share/man/man9/sema.9
+++ b/share/man/man9/sema.9
@@ -98,13 +98,26 @@ argument to
 .Fn sema_timedwait
 specifies the minimum time in ticks to wait before returning with failure.
 .Fn sema_value
+is used to read the current value of the semaphore.
+.Sh RETURN VALUES
+.Fn sema_value
 returns the current value of the semaphore.
 .Pp
-.Fn sema_timedwait
-and
+If decrementing the semaphore would result in its value being negative,
 .Fn sema_trywait
-will return 0 if waiting on the semaphore failed; otherwise a non-zero value
-will be returned to indicate success.
+returns 0 to indicate failure.
+Otherwise, a non-zero value is returned to indicate success.
+.Pp
+.Fn sema_timedwait
+returns 0 if waiting on the semaphore succeeded; otherwise a
+non-zero error code is returned.
+.Sh ERRORS
+.Fn sema_timedwait
+will fail if:
+.Bl -tag -width Er
+.It Bq Er EWOULDBLOCK
+Timeout expired.
+.El
 .Sh SEE ALSO
 .Xr condvar 9 ,
 .Xr mtx_pool 9 ,