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Break out allocation of new ifindex values from if_alloc() and if_vmove(),

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and centralize in a single function ifindex_alloc().  Assert the
IFNET_WLOCK, and add missing IFNET_WLOCK in if_alloc().  This does not
close all known races in this code.

Reviewed by:	bz
MFC after:	3 days
This commit is contained in:
Robert Watson 2009-08-25 20:21:16 +00:00
parent 28ef31c725
commit 61f6986b07
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=196553
1 changed files with 42 additions and 34 deletions
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76
sys/net/if.c
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@ -223,6 +223,37 @@ ifnet_byindex_ref(u_short idx)
return (ifp);
}
/*
* Allocate an ifindex array entry; return 0 on success or an error on
* failure.
*/
static int
ifindex_alloc(u_short *idxp)
{
u_short idx;
IFNET_WLOCK_ASSERT();
/*
* Try to find an empty slot below if_index. If we fail, take the
* next slot.
*/
for (idx = 1; idx <= V_if_index; idx++) {
if (ifnet_byindex_locked(idx) == NULL)
break;
}
/* Catch if_index overflow. */
if (idx < 1)
return (ENOSPC);
if (idx > V_if_index)
V_if_index = idx;
if (V_if_index >= V_if_indexlim)
if_grow();
*idxp = idx;
return (0);
}
static void
ifnet_setbyindex_locked(u_short idx, struct ifnet *ifp)
{
@ -335,32 +366,19 @@ struct ifnet *
if_alloc(u_char type)
{
struct ifnet *ifp;
u_short idx;
ifp = malloc(sizeof(struct ifnet), M_IFNET, M_WAITOK|M_ZERO);
/*
* Try to find an empty slot below if_index. If we fail, take
* the next slot.
*
* XXX: should be locked!
*/
for (ifp->if_index = 1; ifp->if_index <= V_if_index; ifp->if_index++) {
if (ifnet_byindex(ifp->if_index) == NULL)
break;
}
/* Catch if_index overflow. */
if (ifp->if_index < 1) {
IFNET_WLOCK();
if (ifindex_alloc(&idx) != 0) {
IFNET_WUNLOCK();
free(ifp, M_IFNET);
return (NULL);
}
if (ifp->if_index > V_if_index)
V_if_index = ifp->if_index;
if (V_if_index >= V_if_indexlim)
if_grow();
IFNET_WUNLOCK();
ifp->if_index = idx;
ifp->if_type = type;
ifp->if_alloctype = type;
if (if_com_alloc[type] != NULL) {
ifp->if_l2com = if_com_alloc[type](type, ifp);
if (ifp->if_l2com == NULL) {
@ -882,6 +900,7 @@ if_detach_internal(struct ifnet *ifp, int vmove)
void
if_vmove(struct ifnet *ifp, struct vnet *new_vnet)
{
u_short idx;
/*
* Detach from current vnet, but preserve LLADDR info, do not
@ -907,23 +926,12 @@ if_vmove(struct ifnet *ifp, struct vnet *new_vnet)
*/
CURVNET_SET_QUIET(new_vnet);
/*
* Try to find an empty slot below if_index. If we fail, take
* the next slot.
*/
IFNET_WLOCK();
for (ifp->if_index = 1; ifp->if_index <= V_if_index; ifp->if_index++) {
if (ifnet_byindex_locked(ifp->if_index) == NULL)
break;
}
/* Catch if_index overflow. */
if (ifp->if_index < 1)
if (ifindex_alloc(&idx) != 0) {
IFNET_WUNLOCK();
panic("if_index overflow");
if (ifp->if_index > V_if_index)
V_if_index = ifp->if_index;
if (V_if_index >= V_if_indexlim)
if_grow();
}
ifp->if_index = idx;
ifnet_setbyindex_locked(ifp->if_index, ifp);
IFNET_WUNLOCK();