svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
sysctl_remove_oid(9)
SYSCTL_ADD_OID(9) BSD Kernel Developer's Manual SYSCTL_ADD_OID(9)
NAME
sysctl_add_oid, sysctl_move_oid, sysctl_remove_oid, sysctl_remove_name —
runtime sysctl tree manipulation
SYNOPSIS
#include <sys/types.h>
#include <sys/sysctl.h>
struct sysctl_oid *
sysctl_add_oid(struct sysctl_ctx_list *ctx,
struct sysctl_oid_list *parent, int number, const char *name,
int kind, void *arg1, intmax_t arg2,
int (*handler) (SYSCTL_HANDLER_ARGS), const char *format,
const char *descr, const char *label);
int
sysctl_move_oid(struct sysctl_oid *oidp, struct sysctl_oid_list *parent);
int
sysctl_remove_oid(struct sysctl_oid *oidp, int del, int recurse);
int
sysctl_remove_name(struct sysctl_oid *oidp, const char *name, int del,
int recurse);
DESCRIPTION
These functions provide the interface for creating and deleting sysctl
OIDs at runtime for example during the lifetime of a module. The wrapper
macros defined by sysctl(9) are recommended when creating new OIDs.
sysctl_add_oid() should not be called directly from the code.
Dynamic OIDs of type CTLTYPE_NODE are reusable so that several code sec‐
tions can create and delete them, but in reality they are allocated and
freed based on their reference count. As a consequence, it is possible
for two or more code sections to create partially overlapping trees that
they both can use. It is not possible to create overlapping leaves, nor
to create different child types with the same name and parent.
The sysctl_add_oid() function creates a raw OID of any type and connects
it to its parent node, if any. If the OID is successfully created, the
function returns a pointer to it else it returns NULL. Many of the argu‐
ments for sysctl_add_oid() are common to the wrapper macros defined by
sysctl(9).
The sysctl_move_oid() function reparents an existing OID. The OID is
assigned a new number as if it had been created with number set to
OID_AUTO.
The sysctl_remove_oid() function removes a dynamically created OID from
the tree and optionally freeing its resources. It takes the following
arguments:
oidp A pointer to the dynamic OID to be removed. If the OID is not
dynamic, or the pointer is NULL, the function returns EINVAL.
del If non-zero, sysctl_remove_oid() will try to free the OID's
resources when the reference count of the OID becomes zero.
However, if del is set to 0, the routine will only deregister
the OID from the tree, without freeing its resources. This be‐
haviour is useful when the caller expects to rollback (possibly
partially failed) deletion of many OIDs later.
recurse If non-zero, attempt to remove the node and all its children.
If recurse is set to 0, any attempt to remove a node that con‐
tains any children will result in a ENOTEMPTY error. WARNING:
use recursive deletion with extreme caution! Normally it should
not be needed if contexts are used. Contexts take care of
tracking inter-dependencies between users of the tree. However,
in some extreme cases it might be necessary to remove part of
the subtree no matter how it was created, in order to free some
other resources. Be aware, though, that this may result in a
system panic(9) if other code sections continue to use removed
subtrees.
The sysctl_remove_name() function looks up the child node matching the
name argument and then invokes the sysctl_remove_oid() function on that
node, passing along the del and recurse arguments. If a node having the
specified name does not exist an error code of ENOENT is returned. Else
the error code from sysctl_remove_oid() is returned.
In most cases the programmer should use contexts, as described in
sysctl_ctx_init(9), to keep track of created OIDs, and to delete them
later in orderly fashion.
SEE ALSO
sysctl(8), sysctl(9), sysctl_ctx_free(9), sysctl_ctx_init(9)
HISTORY
These functions first appeared in FreeBSD 4.2.
AUTHORS
Andrzej Bialecki <abial@FreeBSD.org>
BUGS
Sharing nodes between many code sections causes interdependencies that
sometimes may lock the resources. For example, if module A hooks up a
subtree to an OID created by module B, module B will be unable to delete
that OID. These issues are handled properly by sysctl contexts.
Many operations on the tree involve traversing linked lists. For this
reason, OID creation and removal is relatively costly.
BSD December 13, 2016 BSD