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if_clone: Allow maxunit to be zero

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Some drivers, e.g. if_enc(4), only allow one instance to be created, but
the KPI ifc_attach_cloner() treat zero value of maxunit as not limited,
aka IF_MAXUNIT.

Introduce a new flag IFC_F_LIMITUNIT to indicate that the requested
maxunit is limited and should be respected.

Consumers should use the new flag if there is an intended limit.

Reviewed by:	glebius
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D45757
This commit is contained in:
Zhenlei Huang 2024-07-03 21:14:08 +08:00
parent a1cfe4c764
commit a2cac544a6
2 changed files with 14 additions and 4 deletions
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13
sys/net/if_clone.c
View File

@ -483,12 +483,13 @@ if_clone_alloc(const char *name, int maxunit)
struct if_clone *ifc;
KASSERT(name != NULL, ("%s: no name\n", __func__));
MPASS(maxunit >= 0);
ifc = malloc(sizeof(struct if_clone), M_CLONE, M_WAITOK | M_ZERO);
strncpy(ifc->ifc_name, name, IFCLOSIZ-1);
IF_CLONE_LOCK_INIT(ifc);
IF_CLONE_ADDREF(ifc);
ifc->ifc_maxunit = maxunit ? maxunit : IF_MAXUNIT;
ifc->ifc_maxunit = maxunit;
ifc->ifc_unrhdr = new_unrhdr(0, ifc->ifc_maxunit, &ifc->ifc_mtx);
LIST_INIT(&ifc->ifc_iflist);
@ -521,12 +522,16 @@ if_clone_attach(struct if_clone *ifc)
struct if_clone *
ifc_attach_cloner(const char *name, struct if_clone_addreq *req)
{
int maxunit;
struct if_clone *ifc;
if (req->create_f == NULL || req->destroy_f == NULL)
return (NULL);
if (strnlen(name, IFCLOSIZ) >= (IFCLOSIZ - 1))
return (NULL);
struct if_clone *ifc = if_clone_alloc(name, req->maxunit);
maxunit = (req->flags & IFC_F_LIMITUNIT) ? req->maxunit : IF_MAXUNIT;
ifc = if_clone_alloc(name, maxunit);
ifc->ifc_match = req->match_f != NULL ? req->match_f : ifc_simple_match;
ifc->ifc_create = req->create_f;
ifc->ifc_destroy = req->destroy_f;
@ -584,7 +589,7 @@ if_clone_advanced(const char *name, u_int maxunit, ifc_match_t match,
{
struct if_clone *ifc;
ifc = if_clone_alloc(name, maxunit);
ifc = if_clone_alloc(name, maxunit ? maxunit : IF_MAXUNIT);
ifc->ifc_match = match;
ifc->ifc_create = ifc_advanced_create_wrapper;
ifc->ifc_destroy = ifc_advanced_destroy_wrapper;
@ -629,7 +634,7 @@ if_clone_simple(const char *name, ifcs_create_t create, ifcs_destroy_t destroy,
struct if_clone *ifc;
u_int unit;
ifc = if_clone_alloc(name, 0);
ifc = if_clone_alloc(name, IF_MAXUNIT);
ifc->ifc_match = ifc_simple_match;
ifc->ifc_create = ifc_simple_create_wrapper;
ifc->ifc_destroy = ifc_simple_destroy_wrapper;

5
sys/net/if_clone.h
View File

@ -101,6 +101,11 @@ struct if_clone_addreq_v2 {
#define IFC_F_SYSSPACE 0x04 /* Cloner callback: params pointer is in kernel memory */
#define IFC_F_FORCE 0x08 /* Deletion flag: force interface deletion */
#define IFC_F_CREATE 0x10 /* Creation flag: indicate creation request */
#define IFC_F_LIMITUNIT 0x20 /* Creation flag: the unit number is limited */
_Static_assert(offsetof(struct if_clone_addreq, destroy_f) ==
offsetof(struct if_clone_addreq_v2, destroy_f),
"destroy_f in if_clone_addreq and if_clone_addreq_v2 are at different offset");
struct if_clone *ifc_attach_cloner(const char *name, struct if_clone_addreq *req);
void ifc_detach_cloner(struct if_clone *ifc);