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ifnet: allocate index at the end of if_alloc_domain()

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Now that if_alloc_domain() never fails and actually doesn't
expose ifnet to outside we can eliminate IFNET_HOLD and two
step index allocation.

Reviewed by:		kp
Differential revision:	https://reviews.freebsd.org/D33259
This commit is contained in:
Gleb Smirnoff 2021-12-04 09:49:35 -08:00
parent 8f07932272
commit 8062e5759c
1 changed files with 15 additions and 23 deletions
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38
sys/net/if.c
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@ -331,13 +331,6 @@ struct sx ifnet_detach_sxlock;
SX_SYSINIT_FLAGS(ifnet_detach, &ifnet_detach_sxlock, "ifnet_detach_sx",
SX_RECURSE);
/*
* The allocation of network interfaces is a rather non-atomic affair; we
* need to select an index before we are ready to expose the interface for
* use, so will use this pointer value to indicate reservation.
*/
#define IFNET_HOLD (void *)(uintptr_t)(-1)
#ifdef VIMAGE
#define VNET_IS_SHUTTING_DOWN(_vnet) \
((_vnet)->vnet_shutdown && (_vnet)->vnet_state < SI_SUB_VNET_DONE)
@ -353,13 +346,11 @@ MALLOC_DEFINE(M_IFMADDR, "ether_multi", "link-level multicast address");
struct ifnet *
ifnet_byindex(u_short idx)
{
struct ifnet *ifp;
if (__predict_false(idx > V_if_index))
return (NULL);
ifp = *(struct ifnet * const volatile *)(V_ifindex_table + idx);
return (__predict_false(ifp == IFNET_HOLD) ? NULL : ifp);
return (V_ifindex_table[idx]);
}
struct ifnet *
@ -422,6 +413,7 @@ static void
ifnet_setbyindex(u_short idx, struct ifnet *ifp)
{
ifp->if_index = idx;
V_ifindex_table[idx] = ifp;
}
@ -608,18 +600,6 @@ if_alloc_domain(u_char type, int numa_domain)
else
ifp = malloc_domainset(sizeof(struct ifnet), M_IFNET,
DOMAINSET_PREF(numa_domain), M_WAITOK | M_ZERO);
restart:
IFNET_WLOCK();
idx = ifindex_alloc(&old);
if (__predict_false(idx == USHRT_MAX)) {
IFNET_WUNLOCK();
epoch_wait_preempt(net_epoch_preempt);
free(old, M_IFNET);
goto restart;
}
ifnet_setbyindex(idx, IFNET_HOLD);
IFNET_WUNLOCK();
ifp->if_index = idx;
ifp->if_type = type;
ifp->if_alloctype = type;
ifp->if_numa_domain = numa_domain;
@ -650,7 +630,19 @@ if_alloc_domain(u_char type, int numa_domain)
ifp->if_counters[i] = counter_u64_alloc(M_WAITOK);
ifp->if_get_counter = if_get_counter_default;
ifp->if_pcp = IFNET_PCP_NONE;
ifnet_setbyindex(ifp->if_index, ifp);
restart:
IFNET_WLOCK();
idx = ifindex_alloc(&old);
if (__predict_false(idx == USHRT_MAX)) {
IFNET_WUNLOCK();
epoch_wait_preempt(net_epoch_preempt);
free(old, M_IFNET);
goto restart;
}
ifnet_setbyindex(idx, ifp);
IFNET_WUNLOCK();
return (ifp);
}