Introduce a new 'softclock' thread that will be used to execute timeout

callbacks needing a process context.

The function timeout_set_proc(9) has to be used instead of timeout_set(9)
when a timeout callback needs a process context.

Note that if such a timeout is waiting, understand sleeping, for a non
negligible amount of time it might delay other timeouts needing a process
context.

dlg@ agrees with this as a temporary solution.

Manpage tweaks from jmc@

ok kettenis@, bluhm@, mikeb@

1 files changed, 19 insertions, 5 deletions

diff --git a/share/man/man9/timeout.9 b/share/man/man9/timeout.9
index 8701c920a2c..ec0c96d086f 100644
--- a/share/man/man9/timeout.9
+++ b/share/man/man9/timeout.9
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: timeout.9,v 1.43 2016/06/14 15:58:03 bluhm Exp $
+.\"	$OpenBSD: timeout.9,v 1.44 2016/09/22 12:55:24 mpi Exp $
 .\"
 .\" Copyright (c) 2000 Artur Grabowski <art@openbsd.org>
 .\" All rights reserved.
@@ -23,11 +23,12 @@
 .\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 .\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: June 14 2016 $
+.Dd $Mdocdate: September 22 2016 $
 .Dt TIMEOUT_SET 9
 .Os
 .Sh NAME
 .Nm timeout_set ,
+.Nm timeout_set_proc ,
 .Nm timeout_add ,
 .Nm timeout_add_sec ,
 .Nm timeout_add_msec ,
@@ -47,6 +48,8 @@
 .In sys/timeout.h
 .Ft void
 .Fn timeout_set "struct timeout *to" "void (*fn)(void *)" "void *arg"
+.Ft void
+.Fn timeout_set_proc "struct timeout *to" "void (*fn)(void *)" "void *arg"
 .Ft int
 .Fn timeout_add "struct timeout *to" "int ticks"
 .Ft int
@@ -85,9 +88,11 @@ times a second.
 It is the responsibility of the caller to provide these functions with
 pre-allocated timeout structures.
 .Pp
-The function
+The functions
 .Fn timeout_set
-prepares the timeout structure
+and
+.Fn timeout_set_proc
+prepare the timeout structure
 .Fa to
 to be used in future calls to
 .Fn timeout_add
@@ -128,8 +133,12 @@ The timeout in the
 .Fa to
 argument must be already initialized by
 .Fn timeout_set
+or
+.Fn timeout_set_proc
 and may not be used in calls to
 .Fn timeout_set
+or
+.Fn timeout_set_proc
 until it has timed out or been removed with
 .Fn timeout_del .
 If the timeout in the
@@ -188,6 +197,8 @@ argument given in
 .Fa arg .
 .Sh CONTEXT
 .Fn timeout_set
+and
+.Fn timeout_set_proc
 can be called during autoconf, from process context, or from interrupt
 context.
 .Pp
@@ -211,8 +222,11 @@ When the timeout runs, the
 .Fa fn
 argument to
 .Fn timeout_set
+or
+.Fn timeout_set_proc
 will be called in an interrupt context at
-.Dv IPL_SOFTCLOCK .
+.Dv IPL_SOFTCLOCK
+or a process context, respectively.
 .Sh RETURN VALUES
 .Fn timeout_add ,
 .Fn timeout_add_sec ,