Tun_metadata can be referened by flow and frozen_state at the same time. When ovs-vswitchd handles TLV table mod message, the involved tun_metadata gets freed. The call trace to free tun_metadata is shown as below:
ofproto_run - handle_openflow - handle_single_part_openflow - handle_tlv_table_mod - tun_metadata_table_mod - tun_metadata_postpone_free Unfortunately, this tun_metadata can be still used by some frozen_state, and later on when frozen_state tries to access its tun_metadata table, ovs-vswitchd crashes. The call trace to access tun_metadata from frozen_state is shown as below: udpif_upcall_handler - recv_upcalls - process_upcall - frozen_metadata_to_flow This patch fixes it by introducing a reference count to tun_metadata. Whenever a pointer of tun_metadata is passed between flow and frozen_state, we increase its reference count. Reference count is decreased at deallocation. In present code, pointer of tun_metadata can be passed between flows. It is safe because of RCU mechanism. VMware-BZ: #2526222 Signed-off-by: Yifeng Sun <pkusunyif...@gmail.com> --- lib/tun-metadata.c | 29 ++++++++++++++++++++++++++++- lib/tun-metadata.h | 2 ++ ofproto/ofproto-dpif-rid.c | 8 ++++++++ ofproto/ofproto-dpif-rid.h | 2 ++ 4 files changed, 40 insertions(+), 1 deletion(-) diff --git a/lib/tun-metadata.c b/lib/tun-metadata.c index f8a0e19524e9..c4218a034a92 100644 --- a/lib/tun-metadata.c +++ b/lib/tun-metadata.c @@ -25,6 +25,7 @@ #include "nx-match.h" #include "odp-netlink.h" #include "openvswitch/ofp-match.h" +#include "ovs-atomic.h" #include "ovs-rcu.h" #include "packets.h" #include "tun-metadata.h" @@ -40,6 +41,11 @@ struct tun_meta_entry { /* Maps from TLV option class+type to positions in a struct tun_metadata's * 'opts' array. */ struct tun_table { + /* Struct tun_table can be referenced by struct frozen_state for a long + * time. This ref_cnt protects tun_table from being freed if it is still + * being used somewhere. */ + struct ovs_refcount ref_cnt; + /* TUN_METADATA<i> is stored in element <i>. */ struct tun_meta_entry entries[TUN_METADATA_NUM_OPTS]; @@ -79,6 +85,24 @@ tun_key_type(uint32_t key) return key & 0xff; } +void +tun_metadata_ref(const struct tun_table *tab) +{ + if (tab) { + ovs_refcount_ref(&CONST_CAST(struct tun_table *, tab)->ref_cnt); + } +} + +unsigned int +tun_metadata_unref(const struct tun_table *tab) +{ + if (tab) { + return ovs_refcount_unref_relaxed( + &CONST_CAST(struct tun_table *, tab)->ref_cnt); + } + return -1; +} + /* Returns a newly allocated tun_table. If 'old_map' is nonnull then the new * tun_table is a deep copy of the old one. */ struct tun_table * @@ -111,6 +135,7 @@ tun_metadata_alloc(const struct tun_table *old_map) hmap_init(&new_map->key_hmap); } + ovs_refcount_init(&new_map->ref_cnt); return new_map; } @@ -135,7 +160,9 @@ tun_metadata_free(struct tun_table *map) void tun_metadata_postpone_free(struct tun_table *tab) { - ovsrcu_postpone(tun_metadata_free, tab); + if (tun_metadata_unref(tab) == 1) { + ovsrcu_postpone(tun_metadata_free, tab); + } } enum ofperr diff --git a/lib/tun-metadata.h b/lib/tun-metadata.h index 7dad9504b8da..933021a0f679 100644 --- a/lib/tun-metadata.h +++ b/lib/tun-metadata.h @@ -33,6 +33,8 @@ struct ofputil_tlv_table_mod; struct ofputil_tlv_table_reply; struct tun_table; +void tun_metadata_ref(const struct tun_table *tab); +unsigned int tun_metadata_unref(const struct tun_table *tab); struct tun_table *tun_metadata_alloc(const struct tun_table *old_map); void tun_metadata_free(struct tun_table *); void tun_metadata_postpone_free(struct tun_table *); diff --git a/ofproto/ofproto-dpif-rid.c b/ofproto/ofproto-dpif-rid.c index 29aafc2c0b40..d479e53d9b2d 100644 --- a/ofproto/ofproto-dpif-rid.c +++ b/ofproto/ofproto-dpif-rid.c @@ -201,6 +201,7 @@ static void frozen_state_clone(struct frozen_state *new, const struct frozen_state *old) { *new = *old; + tun_metadata_ref(old->metadata.tunnel.metadata.tab); new->stack = (new->stack_size ? xmemdup(new->stack, new->stack_size) : NULL); @@ -218,10 +219,17 @@ frozen_state_clone(struct frozen_state *new, const struct frozen_state *old) static void frozen_state_free(struct frozen_state *state) { + struct tun_table *tab; + free(state->stack); free(state->ofpacts); free(state->action_set); free(state->userdata); + + tab = CONST_CAST(struct tun_table *, state->metadata.tunnel.metadata.tab); + if (tun_metadata_unref(tab) == 1) { + tun_metadata_free(tab); + } } /* Allocate a unique recirculation id for the given set of flow metadata. diff --git a/ofproto/ofproto-dpif-rid.h b/ofproto/ofproto-dpif-rid.h index e5d02caf28a3..1fefbf53b94a 100644 --- a/ofproto/ofproto-dpif-rid.h +++ b/ofproto/ofproto-dpif-rid.h @@ -115,6 +115,7 @@ frozen_metadata_from_flow(struct frozen_metadata *md, { memset(md, 0, sizeof *md); md->tunnel = flow->tunnel; + tun_metadata_ref(flow->tunnel.metadata.tab); md->metadata = flow->metadata; memcpy(md->regs, flow->regs, sizeof md->regs); md->in_port = flow->in_port.ofp_port; @@ -125,6 +126,7 @@ frozen_metadata_to_flow(const struct frozen_metadata *md, struct flow *flow) { flow->tunnel = md->tunnel; + tun_metadata_ref(md->tunnel.metadata.tab); flow->metadata = md->metadata; memcpy(flow->regs, md->regs, sizeof flow->regs); flow->in_port.ofp_port = md->in_port; -- 2.7.4 _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev