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- note that RTF_PRCLONING is obsoleted

Browse Source 
- explain locking differencies between rtalloc(), rtalloc_ign(), rtalloc1()
  and rtfree(), RTFREE().

Reviewed by:	andre (1.5 months ago)
OK'd by:	ru
This commit is contained in:
Gleb Smirnoff 2004-10-07 10:14:23 +00:00
parent 57dd0a90b6
commit 729df1bb28
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=136213
1 changed files with 47 additions and 19 deletions
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66
share/man/man9/rtalloc.9
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@ -27,13 +27,14 @@
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.Dd October 8, 1996
.Dd October 7, 2004
.Os
.Dt RTALLOC 9
.Sh NAME
.Nm rtalloc ,
.Nm rtalloc_ign ,
.Nm rtalloc1
.Nm rtalloc1 ,
.Nm rtfree
.Nd look up a route in the kernel routing table
.Sh SYNOPSIS
.In sys/types.h
@ -45,6 +46,9 @@
.Fn rtalloc_ign "struct route *ro" "u_long flags"
.Ft "struct rtentry *"
.Fn rtalloc1 "struct sockaddr *sa" "int report" "u_long flags"
.Ft void
.Fn rtfree "struct rt_entry *rt"
.Fn RTFREE "struct rt_entry *rt"
.Sh DESCRIPTION
The kernel uses a radix tree structure to manage routes for the
networking subsystem.
@ -58,22 +62,21 @@ certain protocol\- and interface-specific actions to take place.
.Pp
When a route with the flag
.Dv RTF_CLONING
or
.Dv RTF_PRCLONING
is retrieved, and the action of those flags is not masked, the
is retrieved, and the action of this flag is not masked, the
.Nm
facility automatically generates a new route using information in the
old route as a template, and in the case of
.Dv RTF_CLONING ,
old route as a template, and
sends an
.Dv RTM_RESOLVE
message to the appropriate interface-address route-management routine
.Pq Fn ifa->ifa_rtrequest .
This generated route is called
.Em cloned ,
and has
.Dv RTF_WASCLONED
flag set.
.Dv RTF_PRCLONING
routes are assumed to be managed by the protocol family and no
resolution requests are made, but all routes generated by the cloning
process retain a reference to the route from which they were
generated.
flag is obsoleted and thus ignored by facility.
If the
.Dv RTF_XRESOLVE
flag is set, then the
@ -95,6 +98,7 @@ struct route {
struct sockaddr ro_dst;
struct rtentry *ro_rt;
};
.Pp
.Ed
Thus, this function can only be used for address families which are
smaller than the default
@ -119,9 +123,7 @@ interface can be used when the default actions of
.Fn rtalloc
in the presence of the
.Dv RTF_CLONING
and
.Dv RTF_PRCLONING
flags are undesired.
flag is undesired.
The
.Fa ro
argument is the same as
@ -130,10 +132,15 @@ but there is additionally a
.Fa flags
argument, which lists the flags in the route which are to be
.Em ignored
(ordinarily, one or both of
(in most cases this is
.Dv RTF_CLONING
or
.Dv RTF_PRCLONING ) .
flag) .
Both
.Fn rtalloc
and
.Fn rtalloc_ign
functions return an unlocked
.Ft "struct rtentry" .
.Pp
The
.Fn rtalloc1
@ -166,11 +173,32 @@ The third argument,
.Fa flags ,
is a set of flags to ignore, as in
.Fn rtalloc_ign .
.Fn rtalloc1
returns a locked
.Ft "struct rtentry" .
.Pp
The
.Fn rtfree
function frees a locked route entry, e.g. previously allocated by
.Fn rtalloc1 .
.Pp
.Fn RTFREE
macro is used to free unlocked route entries, previously allocated by
.Fn rtalloc
or
.Fn rtalloc_ign .
The preferred usage is allocating a route using
.Fn rtalloc
or
.Fn rtalloc_ign
and freeing using
.Fn RTFREE .
.Sh RETURN VALUES
The
.Fn rtalloc
and
.Fn rtalloc ,
.Fn rtalloc_ign
and
.Fn rtfree
functions do not return a value.
The
.Fn rtalloc1