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Use VLAN_TAG_VALUE() not only to read a dot1q tag

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value from an m_tag, but also to set it.  This reduces
complex code duplication and improves its readability.

Alas, we shouldn't rename the macro to VLAN_TAG_LVALUE()
globally because that would cause pain for kernel module
port maintainers and vendors using FreeBSD as their codebase.
Added a clarifying comment instead.

Discussed with:	ru, glebius
X-MFC-After:	6.0-RELEASE (MFC is good just to reduce the diff)
This commit is contained in:
Yaroslav Tykhiy 2005-08-31 11:36:50 +00:00
parent a3a90a725c
commit eefbcf0e62
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=149662
2 changed files with 8 additions and 3 deletions
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2
sys/net/if_vlan.c
View File

@ -502,7 +502,7 @@ vlan_start(struct ifnet *ifp)
m_freem(m);
continue;
}
*(u_int*)(mtag + 1) = ifv->ifv_tag;
VLAN_TAG_VALUE(mtag) = ifv->ifv_tag;
m_tag_prepend(m, mtag);
m->m_flags |= M_VLANTAG;
} else {

9
sys/net/if_vlan_var.h
View File

@ -96,6 +96,12 @@ struct vlanreq {
#define MTAG_VLAN 1035328035
#define MTAG_VLAN_TAG 0 /* tag of VLAN interface */
/*
* This macro must expand to a lvalue so that it can be used
* to set a tag with a simple assignment.
*/
#define VLAN_TAG_VALUE(_mt) (*(u_int *)((_mt) + 1))
#define VLAN_INPUT_TAG(_ifp, _m, _t, _errcase) do { \
struct m_tag *mtag; \
mtag = m_tag_alloc(MTAG_VLAN, MTAG_VLAN_TAG, \
@ -105,7 +111,7 @@ struct vlanreq {
m_freem(_m); \
_errcase; \
} \
*(u_int *)(mtag+1) = (_t); \
VLAN_TAG_VALUE(mtag) = (_t); \
m_tag_prepend((_m), mtag); \
(_m)->m_flags |= M_VLANTAG; \
} while (0)
@ -113,7 +119,6 @@ struct vlanreq {
#define VLAN_OUTPUT_TAG(_ifp, _m) \
((_m)->m_flags & M_VLANTAG ? \
m_tag_locate((_m), MTAG_VLAN, MTAG_VLAN_TAG, NULL) : NULL)
#define VLAN_TAG_VALUE(_mt) (*(u_int *)((_mt)+1))
#endif /* _KERNEL */
#endif /* _NET_IF_VLAN_VAR_H_ */