docs/132546: [patch] sync vm_map_lock(9) with recent locking changes
pluknet
pluknet at gmail.com
Wed Mar 11 15:10:05 UTC 2009
>Number: 132546
>Category: docs
>Synopsis: [patch] sync vm_map_lock(9) with recent locking changes
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-doc
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Mar 11 15:10:01 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator: pluknet
>Release: FreeBSD 8.0-CURRENT
>Organization:
RIPN
>Environment:
FreeBSD 8.0-CURRENT
>Description:
Quoting commit log to vm_map.c, v1.402:
"Resurrect shared map locks allowing greater concurrency during some map
operations, such as page faults.
[..]
MFC after: 6 weeks"
vm_map_lock(9) was not updated to reflect the reality.
>How-To-Repeat:
>Fix:
Apply the patch.
Patch attached with submission follows:
--- share/man/man9/vm_map_lock.9.orig Wed Mar 11 17:57:55 2009
+++ share/man/man9/vm_map_lock.9 Wed Mar 11 17:59:54 2009
@@ -73,7 +73,6 @@
.Fn vm_map_lock_read
macro obtains a read-lock on
.Fa map .
-Currently this is implemented as an exclusive lock.
.Pp
The
.Fn vm_map_unlock_read
@@ -93,23 +92,18 @@
.Fa map .
It returns FALSE if the lock cannot be immediately acquired;
otherwise return TRUE with the lock acquired.
-Currently this is implemented as an exclusive lock.
.Pp
The
.Fn vm_map_lock_upgrade
macro attempts to atomically upgrade a read-lock on
.Fa map
to an exclusive lock.
-As read-locks are currently implemented as exclusive locks,
-this macro is a no-op.
.Pp
The
.Fn vm_map_lock_downgrade
macro attempts to downgrade an exclusive lock on
.Fa map
to a read-lock.
-As read-locks are currently implemented as exclusive locks,
-this macro is a no-op.
.Sh IMPLEMENTATION NOTES
Currently, all of the locking macros implement their locks as sleep locks.
.Sh SEE ALSO
>Release-Note:
>Audit-Trail:
>Unformatted:
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