mirror/freebsd
1
0
Fork 0
mirror of https://git.FreeBSD.org/src.git synced 2024-12-16 10:20:30 +00:00
Code Issues Releases Activity

Fix the prototypes for cpu_critical_exit and cpu_critical_enter and update

Browse Source 
the text to reflect the changes.

Update the header files list.
This commit is contained in:
Chad David 2002-04-12 05:06:38 +00:00
parent 6a00ed1536
commit f972f99474
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=94479
1 changed files with 8 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
share/man/man9/critical_enter.9
View File

@ -34,12 +34,14 @@
.Nm critical_exit
.Nd enter and exit a critical region
.Sh SYNOPSIS
.In sys/types.h
.In sys/param.h
.In sys/proc.h
.In sys/systm.h
.Ft critical_t
.In machine/critical.h
.Ft void
.Fn cpu_critical_enter "void"
.Ft void
.Fn cpu_critical_exit "critical_t savecrit"
.Fn cpu_critical_exit "void"
.Ft void
.Fn critical_enter "void"
.Ft void
@ -59,13 +61,6 @@ and
.Fn cpu_critical_exit
functions provide the machine dependent disabling of preemption, normally
by disabling interrupts on the local CPU.
The
.Fn cpu_critical_enter
function returns an opaque value of type
.Vt critical_t .
This value must be passed to the
.Fn cpu_critical_exit
function when leaving the critical region.
.Pp
The
.Fn critical_enter
@ -73,10 +68,7 @@ and
.Fn critical_exit
functions provide a machine independent wrapper around the machine dependent
API.
This wrapper currently saves state regarding nested critical sections as
well as the
.Vt critical_t
value inside of a critical region in per-thread variables.
This wrapper currently saves state regarding nested critical sections.
Nearly all code should use these versions of the API.
.Pp
Note that these functions are not required to provide any inter-CPU
@ -87,15 +79,8 @@ be used to protect shared data structures.
.Pp
These functions should be used with care as an infinite loop within a
critical region will deadlock the CPU.
Also, the machine dependent and machine independent functions should not
be interlocked, and neither pair of functions should be interlocked with
operations on mutexes, sx locks, semaphores, or other synchronization
primitives.
.Sh RETURN VALUES
The
.Fn cpu_critical_enter
function returns an opaque value that must be passed to a corresponding call to
.Fn cpu_critical_exit .
Also, they should not be interlocked with operations on mutexes, sx locks,
semaphores, or other synchronization primitives.
.Sh EXAMPLES
This example demonstrates the use of
.Fn critical_enter