git: 4d7a1361ef32 - main - ifnet/mbuf: provide KPI to serialize/restore m->m_pkthdr.rcvif
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Date: Thu, 05 May 2022 19:14:50 UTC
The branch main has been updated by emaste: URL: https://cgit.FreeBSD.org/src/commit/?id=4d7a1361ef3227fd3d78c7a5da132cbba351dc9d commit 4d7a1361ef3227fd3d78c7a5da132cbba351dc9d Author: Gleb Smirnoff <glebius@FreeBSD.org> AuthorDate: 2022-01-27 05:58:50 +0000 Commit: Ed Maste <emaste@FreeBSD.org> CommitDate: 2022-05-05 18:38:07 +0000 ifnet/mbuf: provide KPI to serialize/restore m->m_pkthdr.rcvif Supplement ifindex table with generation count and use it to serialize & restore an ifnet pointer. Reviewed by: kp Differential revision: https://reviews.freebsd.org/D33266 Fun note: git show e6abef09187a (cherry picked from commit e1882428dcbbafd2814d7e17b977a8f686784b39) --- sys/kern/kern_mbuf.c | 22 ++++++++++++++++++++++ sys/net/if.c | 49 ++++++++++++++++++++++++++++++++++++------------- sys/net/if_var.h | 9 ++++++++- sys/sys/mbuf.h | 6 ++++++ 4 files changed, 72 insertions(+), 14 deletions(-) diff --git a/sys/kern/kern_mbuf.c b/sys/kern/kern_mbuf.c index f1e76ef00c65..5c69f663c0e2 100644 --- a/sys/kern/kern_mbuf.c +++ b/sys/kern/kern_mbuf.c @@ -1635,6 +1635,28 @@ m_snd_tag_destroy(struct m_snd_tag *mst) counter_u64_add(snd_tag_count, -1); } +void +m_rcvif_serialize(struct mbuf *m) +{ + u_short idx, gen; + + M_ASSERTPKTHDR(m); + idx = m->m_pkthdr.rcvif->if_index; + gen = m->m_pkthdr.rcvif->if_idxgen; + m->m_pkthdr.rcvidx = idx; + m->m_pkthdr.rcvgen = gen; +} + +struct ifnet * +m_rcvif_restore(struct mbuf *m) +{ + + M_ASSERTPKTHDR(m); + + return ((m->m_pkthdr.rcvif = ifnet_byindexgen(m->m_pkthdr.rcvidx, + m->m_pkthdr.rcvgen))); +} + /* * Allocate an mbuf with anonymous external pages. */ diff --git a/sys/net/if.c b/sys/net/if.c index 3b303fe42e99..ff7071cea364 100644 --- a/sys/net/if.c +++ b/sys/net/if.c @@ -313,7 +313,10 @@ VNET_DEFINE(struct ifgrouphead, ifg_head); /* Table of ifnet by index. */ static int if_index; static int if_indexlim = 8; -static struct ifnet **ifindex_table; +static struct ifindex_entry { + struct ifnet *ife_ifnet; + uint16_t ife_gencnt; +} *ifindex_table; SYSCTL_NODE(_net_link_generic, IFMIB_SYSTEM, system, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, @@ -325,8 +328,8 @@ sysctl_ifcount(SYSCTL_HANDLER_ARGS) IFNET_RLOCK(); for (int i = 1; i <= if_index; i++) - if (ifindex_table[i] != NULL && - ifindex_table[i]->if_vnet == curvnet) + if (ifindex_table[i].ife_ifnet != NULL && + ifindex_table[i].ife_ifnet->if_vnet == curvnet) rv = i; IFNET_RUNLOCK(); @@ -370,7 +373,7 @@ ifnet_byindex(u_int idx) if (__predict_false(idx > if_index)) return (NULL); - ifp = ck_pr_load_ptr(&ifindex_table[idx]); + ifp = ck_pr_load_ptr(&ifindex_table[idx].ife_ifnet); if (curvnet != NULL && ifp != NULL && ifp->if_vnet != curvnet) ifp = NULL; @@ -391,6 +394,24 @@ ifnet_byindex_ref(u_int idx) return (ifp); } +struct ifnet * +ifnet_byindexgen(uint16_t idx, uint16_t gen) +{ + struct ifnet *ifp; + + NET_EPOCH_ASSERT(); + + if (__predict_false(idx > if_index)) + return (NULL); + + ifp = ck_pr_load_ptr(&ifindex_table[idx].ife_ifnet); + + if (ifindex_table[idx].ife_gencnt == gen) + return (ifp); + else + return (NULL); +} + /* * Network interface utility routines. * @@ -557,13 +578,13 @@ if_alloc_domain(u_char type, int numa_domain) * next slot. */ for (idx = 1; idx <= if_index; idx++) { - if (ifindex_table[idx] == NULL) + if (ifindex_table[idx].ife_ifnet == NULL) break; } /* Catch if_index overflow. */ if (idx >= if_indexlim) { - struct ifnet **new, **old; + struct ifindex_entry *new, *old; int newlim; newlim = if_indexlim * 2; @@ -579,7 +600,8 @@ if_alloc_domain(u_char type, int numa_domain) if_index = idx; ifp->if_index = idx; - ck_pr_store_ptr(&ifindex_table[idx], ifp); + ifp->if_idxgen = ifindex_table[idx].ife_gencnt; + ck_pr_store_ptr(&ifindex_table[idx].ife_ifnet, ifp); IFNET_WUNLOCK(); return (ifp); @@ -654,9 +676,10 @@ if_free(struct ifnet *ifp) * virtualized and interface would outlive the vnet. */ IFNET_WLOCK(); - MPASS(ifindex_table[ifp->if_index] == ifp); - ck_pr_store_ptr(&ifindex_table[ifp->if_index], NULL); - while (if_index > 0 && ifindex_table[if_index] == NULL) + MPASS(ifindex_table[ifp->if_index].ife_ifnet == ifp); + ck_pr_store_ptr(&ifindex_table[ifp->if_index].ife_ifnet, NULL); + ifindex_table[ifp->if_index].ife_gencnt++; + while (if_index > 0 && ifindex_table[if_index].ife_ifnet == NULL) if_index--; IFNET_WUNLOCK(); @@ -805,7 +828,7 @@ if_attach_internal(struct ifnet *ifp, bool vmove) struct sockaddr_dl *sdl; struct ifaddr *ifa; - MPASS(ifindex_table[ifp->if_index] == ifp); + MPASS(ifindex_table[ifp->if_index].ife_ifnet == ifp); #ifdef VIMAGE ifp->if_vnet = curvnet; @@ -4494,8 +4517,8 @@ if_show_ifnet(struct ifnet *ifp) IF_DB_PRINTF("%d", if_dunit); IF_DB_PRINTF("%s", if_description); IF_DB_PRINTF("%u", if_index); + IF_DB_PRINTF("%d", if_idxgen); IF_DB_PRINTF("%u", if_refcount); - IF_DB_PRINTF("%d", if_index_reserved); IF_DB_PRINTF("%p", if_softc); IF_DB_PRINTF("%p", if_l2com); IF_DB_PRINTF("%p", if_llsoftc); @@ -4550,7 +4573,7 @@ DB_SHOW_ALL_COMMAND(ifnets, db_show_all_ifnets) u_short idx; for (idx = 1; idx <= if_index; idx++) { - ifp = ifindex_table[idx]; + ifp = ifindex_table[idx].ife_ifnet; if (ifp == NULL) continue; db_printf( "%20s ifp=%p\n", ifp->if_xname, ifp); diff --git a/sys/net/if_var.h b/sys/net/if_var.h index d741d8abee2e..e054c613e9e6 100644 --- a/sys/net/if_var.h +++ b/sys/net/if_var.h @@ -334,7 +334,7 @@ struct ifnet { const char *if_dname; /* driver name */ int if_dunit; /* unit or IF_DUNIT_NONE */ u_short if_index; /* numeric abbreviation for this if */ - short if_index_reserved; /* spare space to grow if_index */ + u_short if_idxgen; /* ... and its generation count */ char if_xname[IFNAMSIZ]; /* external name (name + unit) */ char *if_description; /* interface description */ @@ -644,6 +644,13 @@ extern struct sx ifnet_sxlock; struct ifnet *ifnet_byindex(u_int); struct ifnet *ifnet_byindex_ref(u_int); +/* + * ifnet_byindexgen() looks up ifnet by index and generation count, + * attempting to restore a weak pointer that had been stored across + * the epoch. + */ +struct ifnet *ifnet_byindexgen(uint16_t idx, uint16_t gen); + VNET_DECLARE(struct ifnethead, ifnet); VNET_DECLARE(struct ifgrouphead, ifg_head); VNET_DECLARE(struct ifnet *, loif); /* first loopback interface */ diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h index 8ca23b60269d..78b175ebe2c0 100644 --- a/sys/sys/mbuf.h +++ b/sys/sys/mbuf.h @@ -159,6 +159,10 @@ struct pkthdr { union { struct m_snd_tag *snd_tag; /* send tag, if any */ struct ifnet *rcvif; /* rcv interface */ + struct { + uint16_t rcvidx; /* rcv interface index ... */ + uint16_t rcvgen; /* ... and generation count */ + }; }; SLIST_HEAD(packet_tags, m_tag) tags; /* list of packet tags */ int32_t len; /* total packet length */ @@ -862,6 +866,8 @@ int m_snd_tag_alloc(struct ifnet *, void m_snd_tag_init(struct m_snd_tag *, struct ifnet *, const struct if_snd_tag_sw *); void m_snd_tag_destroy(struct m_snd_tag *); +void m_rcvif_serialize(struct mbuf *); +struct ifnet *m_rcvif_restore(struct mbuf *); static __inline int m_gettype(int size)