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spl*() functions block interrupts of lesser or equal priority, not

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higher priority.  do some copy editing while I'm here.
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mikel 1997-11-20 05:47:42 +00:00
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share/man/man9/spl.9
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@ -1,4 +1,4 @@
.\" $NetBSD: spl.9,v 1.3 1997/11/11 10:07:25 mrg Exp $
.\" $NetBSD: spl.9,v 1.4 1997/11/20 05:47:42 mikel Exp $
.\"
.\" Copyright (c) 1997 Michael Long.
.\" Copyright (c) 1997 Jonathan Stone.
@ -78,21 +78,25 @@
.Fn splx "int s"
.Sh DESCRIPTION
These functions raise and lower the system priority level.
They are used by kernel code running at any given priority level to
block higher-priority interrupts, so that it can safely access
variables or data structures which are used by kernel code that runs
at a higher priority level.
They are used by kernel code to block interrupts with priority less
than or equal to the named level (e.g.
.Fn spltty
blocks interrupts of priority less than or equal to
.Dv IPL_TTY Ns ).
The code may then safely access variables or data structures which are
read or modified by interrupt service routines that run at the named
level.
.Pp
A
.Nm
function exists for each distinct priority level which can exist in
the system. These macros and the corresponding priority levels are
the system. These functions and the corresponding priority levels are
used for various defined purposes, and may be divided into two main
types: hard and soft. Hard interrupts are generated by hardware
devices, while soft interrupts are generated by callouts and called
devices. Soft interrupts are generated by callouts, and are called
from the kernel's periodic timer interrupt service routine.
.Pp
In order of highest to lowest priority, the priority-raising macros
In order of highest to lowest priority, the priority-raising functions
are:
.Bl -tag -width splsoftserialXX
.It Fn splhigh
@ -142,7 +146,7 @@ blocks hard interrupts from disks and other mass-storage devices.
blocks soft network interrupts.
.El
.Pp
Two macros lower the system priority level. They are:
Two functions lower the system priority level. They are:
.Bl -tag -width splsoftclockXX
.It Fn splsoftclock
unblocks all interrupts but the soft clock interrupt.
@ -152,8 +156,8 @@ unblocks all interrupts.
.Pp
The
.Fn splx
macro restores the system priority level to the one encoded in
function restores the system priority level to the one encoded in
.Fa s ,
which must be a value previously returned by one of the other
.Nm
macros.
functions.