From 349eb8cf45aadd35836fdfde75b3265a01b2aaa1 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Sat, 14 May 2011 11:56:16 +0200 Subject: [PATCH] mac80211: annotate and fix RCU in mesh code This adds proper RCU annotations to the mesh path table code, and fixes a number of bugs in the code that I found while checking the sparse warnings I got as a result of the annotations. Some things like the changes in mesh_path_add() or mesh_pathtbl_init() only serve to shut up sparse, but other changes like the changes surrounding the for_each_mesh_entry() macro fix real RCU bugs in the code. Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- net/mac80211/mesh.h | 4 - net/mac80211/mesh_pathtbl.c | 154 ++++++++++++++++++++++++------------ 2 files changed, 102 insertions(+), 56 deletions(-) diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h index eb733c0d61aa..249e733362e7 100644 --- a/net/mac80211/mesh.h +++ b/net/mac80211/mesh.h @@ -289,10 +289,6 @@ static inline bool mesh_path_sel_is_hwmp(struct ieee80211_sub_if_data *sdata) return sdata->u.mesh.mesh_pp_id == IEEE80211_PATH_PROTOCOL_HWMP; } -#define for_each_mesh_entry(x, p, node, i) \ - for (i = 0; i <= x->hash_mask; i++) \ - hlist_for_each_entry_rcu(node, p, &x->hash_buckets[i], list) - void ieee80211_mesh_notify_scan_completed(struct ieee80211_local *local); void ieee80211_mesh_quiesce(struct ieee80211_sub_if_data *sdata); diff --git a/net/mac80211/mesh_pathtbl.c b/net/mac80211/mesh_pathtbl.c index 74021365b8c8..2bda0ac62326 100644 --- a/net/mac80211/mesh_pathtbl.c +++ b/net/mac80211/mesh_pathtbl.c @@ -36,8 +36,8 @@ struct mpath_node { struct mesh_path *mpath; }; -static struct mesh_table *mesh_paths; -static struct mesh_table *mpp_paths; /* Store paths for MPP&MAP */ +static struct mesh_table __rcu *mesh_paths; +static struct mesh_table __rcu *mpp_paths; /* Store paths for MPP&MAP */ int mesh_paths_generation; @@ -48,6 +48,29 @@ int mesh_paths_generation; static DEFINE_RWLOCK(pathtbl_resize_lock); +static inline struct mesh_table *resize_dereference_mesh_paths(void) +{ + return rcu_dereference_protected(mesh_paths, + lockdep_is_held(&pathtbl_resize_lock)); +} + +static inline struct mesh_table *resize_dereference_mpp_paths(void) +{ + return rcu_dereference_protected(mpp_paths, + lockdep_is_held(&pathtbl_resize_lock)); +} + +/* + * CAREFUL -- "tbl" must not be an expression, + * in particular not an rcu_dereference(), since + * it's used twice. So it is illegal to do + * for_each_mesh_entry(rcu_dereference(...), ...) + */ +#define for_each_mesh_entry(tbl, p, node, i) \ + for (i = 0; i <= tbl->hash_mask; i++) \ + hlist_for_each_entry_rcu(node, p, &tbl->hash_buckets[i], list) + + static struct mesh_table *mesh_table_alloc(int size_order) { int i; @@ -258,12 +281,13 @@ struct mesh_path *mpp_path_lookup(u8 *dst, struct ieee80211_sub_if_data *sdata) */ struct mesh_path *mesh_path_lookup_by_idx(int idx, struct ieee80211_sub_if_data *sdata) { + struct mesh_table *tbl = rcu_dereference(mesh_paths); struct mpath_node *node; struct hlist_node *p; int i; int j = 0; - for_each_mesh_entry(mesh_paths, p, node, i) { + for_each_mesh_entry(tbl, p, node, i) { if (sdata && node->mpath->sdata != sdata) continue; if (j++ == idx) { @@ -293,6 +317,7 @@ int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata) { struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; struct ieee80211_local *local = sdata->local; + struct mesh_table *tbl; struct mesh_path *mpath, *new_mpath; struct mpath_node *node, *new_node; struct hlist_head *bucket; @@ -332,10 +357,12 @@ int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata) spin_lock_init(&new_mpath->state_lock); init_timer(&new_mpath->timer); - hash_idx = mesh_table_hash(dst, sdata, mesh_paths); - bucket = &mesh_paths->hash_buckets[hash_idx]; + tbl = resize_dereference_mesh_paths(); - spin_lock_bh(&mesh_paths->hashwlock[hash_idx]); + hash_idx = mesh_table_hash(dst, sdata, tbl); + bucket = &tbl->hash_buckets[hash_idx]; + + spin_lock_bh(&tbl->hashwlock[hash_idx]); err = -EEXIST; hlist_for_each_entry(node, n, bucket, list) { @@ -345,13 +372,13 @@ int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata) } hlist_add_head_rcu(&new_node->list, bucket); - if (atomic_inc_return(&mesh_paths->entries) >= - mesh_paths->mean_chain_len * (mesh_paths->hash_mask + 1)) + if (atomic_inc_return(&tbl->entries) >= + tbl->mean_chain_len * (tbl->hash_mask + 1)) grow = 1; mesh_paths_generation++; - spin_unlock_bh(&mesh_paths->hashwlock[hash_idx]); + spin_unlock_bh(&tbl->hashwlock[hash_idx]); read_unlock_bh(&pathtbl_resize_lock); if (grow) { set_bit(MESH_WORK_GROW_MPATH_TABLE, &ifmsh->wrkq_flags); @@ -360,7 +387,7 @@ int mesh_path_add(u8 *dst, struct ieee80211_sub_if_data *sdata) return 0; err_exists: - spin_unlock_bh(&mesh_paths->hashwlock[hash_idx]); + spin_unlock_bh(&tbl->hashwlock[hash_idx]); read_unlock_bh(&pathtbl_resize_lock); kfree(new_node); err_node_alloc: @@ -382,11 +409,11 @@ void mesh_mpath_table_grow(void) struct mesh_table *oldtbl, *newtbl; write_lock_bh(&pathtbl_resize_lock); - newtbl = mesh_table_alloc(mesh_paths->size_order + 1); + oldtbl = resize_dereference_mesh_paths(); + newtbl = mesh_table_alloc(oldtbl->size_order + 1); if (!newtbl) goto out; - oldtbl = mesh_paths; - if (mesh_table_grow(mesh_paths, newtbl) < 0) { + if (mesh_table_grow(oldtbl, newtbl) < 0) { __mesh_table_free(newtbl); goto out; } @@ -403,11 +430,11 @@ void mesh_mpp_table_grow(void) struct mesh_table *oldtbl, *newtbl; write_lock_bh(&pathtbl_resize_lock); - newtbl = mesh_table_alloc(mpp_paths->size_order + 1); + oldtbl = resize_dereference_mpp_paths(); + newtbl = mesh_table_alloc(oldtbl->size_order + 1); if (!newtbl) goto out; - oldtbl = mpp_paths; - if (mesh_table_grow(mpp_paths, newtbl) < 0) { + if (mesh_table_grow(oldtbl, newtbl) < 0) { __mesh_table_free(newtbl); goto out; } @@ -422,6 +449,7 @@ int mpp_path_add(u8 *dst, u8 *mpp, struct ieee80211_sub_if_data *sdata) { struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh; struct ieee80211_local *local = sdata->local; + struct mesh_table *tbl; struct mesh_path *mpath, *new_mpath; struct mpath_node *node, *new_node; struct hlist_head *bucket; @@ -456,10 +484,12 @@ int mpp_path_add(u8 *dst, u8 *mpp, struct ieee80211_sub_if_data *sdata) new_mpath->exp_time = jiffies; spin_lock_init(&new_mpath->state_lock); - hash_idx = mesh_table_hash(dst, sdata, mpp_paths); - bucket = &mpp_paths->hash_buckets[hash_idx]; + tbl = resize_dereference_mpp_paths(); - spin_lock_bh(&mpp_paths->hashwlock[hash_idx]); + hash_idx = mesh_table_hash(dst, sdata, tbl); + bucket = &tbl->hash_buckets[hash_idx]; + + spin_lock_bh(&tbl->hashwlock[hash_idx]); err = -EEXIST; hlist_for_each_entry(node, n, bucket, list) { @@ -469,11 +499,11 @@ int mpp_path_add(u8 *dst, u8 *mpp, struct ieee80211_sub_if_data *sdata) } hlist_add_head_rcu(&new_node->list, bucket); - if (atomic_inc_return(&mpp_paths->entries) >= - mpp_paths->mean_chain_len * (mpp_paths->hash_mask + 1)) + if (atomic_inc_return(&tbl->entries) >= + tbl->mean_chain_len * (tbl->hash_mask + 1)) grow = 1; - spin_unlock_bh(&mpp_paths->hashwlock[hash_idx]); + spin_unlock_bh(&tbl->hashwlock[hash_idx]); read_unlock_bh(&pathtbl_resize_lock); if (grow) { set_bit(MESH_WORK_GROW_MPP_TABLE, &ifmsh->wrkq_flags); @@ -482,7 +512,7 @@ int mpp_path_add(u8 *dst, u8 *mpp, struct ieee80211_sub_if_data *sdata) return 0; err_exists: - spin_unlock_bh(&mpp_paths->hashwlock[hash_idx]); + spin_unlock_bh(&tbl->hashwlock[hash_idx]); read_unlock_bh(&pathtbl_resize_lock); kfree(new_node); err_node_alloc: @@ -502,6 +532,7 @@ err_path_alloc: */ void mesh_plink_broken(struct sta_info *sta) { + struct mesh_table *tbl; static const u8 bcast[ETH_ALEN] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; struct mesh_path *mpath; struct mpath_node *node; @@ -510,10 +541,11 @@ void mesh_plink_broken(struct sta_info *sta) int i; rcu_read_lock(); - for_each_mesh_entry(mesh_paths, p, node, i) { + tbl = rcu_dereference(mesh_paths); + for_each_mesh_entry(tbl, p, node, i) { mpath = node->mpath; spin_lock_bh(&mpath->state_lock); - if (mpath->next_hop == sta && + if (rcu_dereference(mpath->next_hop) == sta && mpath->flags & MESH_PATH_ACTIVE && !(mpath->flags & MESH_PATH_FIXED)) { mpath->flags &= ~MESH_PATH_ACTIVE; @@ -542,30 +574,38 @@ void mesh_plink_broken(struct sta_info *sta) */ void mesh_path_flush_by_nexthop(struct sta_info *sta) { + struct mesh_table *tbl; struct mesh_path *mpath; struct mpath_node *node; struct hlist_node *p; int i; - for_each_mesh_entry(mesh_paths, p, node, i) { + rcu_read_lock(); + tbl = rcu_dereference(mesh_paths); + for_each_mesh_entry(tbl, p, node, i) { mpath = node->mpath; - if (mpath->next_hop == sta) + if (rcu_dereference(mpath->next_hop) == sta) mesh_path_del(mpath->dst, mpath->sdata); } + rcu_read_unlock(); } void mesh_path_flush(struct ieee80211_sub_if_data *sdata) { + struct mesh_table *tbl; struct mesh_path *mpath; struct mpath_node *node; struct hlist_node *p; int i; - for_each_mesh_entry(mesh_paths, p, node, i) { + rcu_read_lock(); + tbl = rcu_dereference(mesh_paths); + for_each_mesh_entry(tbl, p, node, i) { mpath = node->mpath; if (mpath->sdata == sdata) mesh_path_del(mpath->dst, mpath->sdata); } + rcu_read_unlock(); } static void mesh_path_node_reclaim(struct rcu_head *rp) @@ -589,6 +629,7 @@ static void mesh_path_node_reclaim(struct rcu_head *rp) */ int mesh_path_del(u8 *addr, struct ieee80211_sub_if_data *sdata) { + struct mesh_table *tbl; struct mesh_path *mpath; struct mpath_node *node; struct hlist_head *bucket; @@ -597,19 +638,20 @@ int mesh_path_del(u8 *addr, struct ieee80211_sub_if_data *sdata) int err = 0; read_lock_bh(&pathtbl_resize_lock); - hash_idx = mesh_table_hash(addr, sdata, mesh_paths); - bucket = &mesh_paths->hash_buckets[hash_idx]; + tbl = resize_dereference_mesh_paths(); + hash_idx = mesh_table_hash(addr, sdata, tbl); + bucket = &tbl->hash_buckets[hash_idx]; - spin_lock_bh(&mesh_paths->hashwlock[hash_idx]); + spin_lock_bh(&tbl->hashwlock[hash_idx]); hlist_for_each_entry(node, n, bucket, list) { mpath = node->mpath; if (mpath->sdata == sdata && - memcmp(addr, mpath->dst, ETH_ALEN) == 0) { + memcmp(addr, mpath->dst, ETH_ALEN) == 0) { spin_lock_bh(&mpath->state_lock); mpath->flags |= MESH_PATH_RESOLVING; hlist_del_rcu(&node->list); call_rcu(&node->rcu, mesh_path_node_reclaim); - atomic_dec(&mesh_paths->entries); + atomic_dec(&tbl->entries); spin_unlock_bh(&mpath->state_lock); goto enddel; } @@ -618,7 +660,7 @@ int mesh_path_del(u8 *addr, struct ieee80211_sub_if_data *sdata) err = -ENXIO; enddel: mesh_paths_generation++; - spin_unlock_bh(&mesh_paths->hashwlock[hash_idx]); + spin_unlock_bh(&tbl->hashwlock[hash_idx]); read_unlock_bh(&pathtbl_resize_lock); return err; } @@ -747,52 +789,60 @@ static int mesh_path_node_copy(struct hlist_node *p, struct mesh_table *newtbl) int mesh_pathtbl_init(void) { - mesh_paths = mesh_table_alloc(INIT_PATHS_SIZE_ORDER); - if (!mesh_paths) + struct mesh_table *tbl_path, *tbl_mpp; + + tbl_path = mesh_table_alloc(INIT_PATHS_SIZE_ORDER); + if (!tbl_path) return -ENOMEM; - mesh_paths->free_node = &mesh_path_node_free; - mesh_paths->copy_node = &mesh_path_node_copy; - mesh_paths->mean_chain_len = MEAN_CHAIN_LEN; + tbl_path->free_node = &mesh_path_node_free; + tbl_path->copy_node = &mesh_path_node_copy; + tbl_path->mean_chain_len = MEAN_CHAIN_LEN; - mpp_paths = mesh_table_alloc(INIT_PATHS_SIZE_ORDER); - if (!mpp_paths) { - mesh_table_free(mesh_paths, true); + tbl_mpp = mesh_table_alloc(INIT_PATHS_SIZE_ORDER); + if (!tbl_mpp) { + mesh_table_free(tbl_path, true); return -ENOMEM; } - mpp_paths->free_node = &mesh_path_node_free; - mpp_paths->copy_node = &mesh_path_node_copy; - mpp_paths->mean_chain_len = MEAN_CHAIN_LEN; + tbl_mpp->free_node = &mesh_path_node_free; + tbl_mpp->copy_node = &mesh_path_node_copy; + tbl_mpp->mean_chain_len = MEAN_CHAIN_LEN; + + /* Need no locking since this is during init */ + RCU_INIT_POINTER(mesh_paths, tbl_path); + RCU_INIT_POINTER(mpp_paths, tbl_mpp); return 0; } void mesh_path_expire(struct ieee80211_sub_if_data *sdata) { + struct mesh_table *tbl; struct mesh_path *mpath; struct mpath_node *node; struct hlist_node *p; int i; - read_lock_bh(&pathtbl_resize_lock); - for_each_mesh_entry(mesh_paths, p, node, i) { + rcu_read_lock(); + tbl = rcu_dereference(mesh_paths); + for_each_mesh_entry(tbl, p, node, i) { if (node->mpath->sdata != sdata) continue; mpath = node->mpath; spin_lock_bh(&mpath->state_lock); if ((!(mpath->flags & MESH_PATH_RESOLVING)) && (!(mpath->flags & MESH_PATH_FIXED)) && - time_after(jiffies, - mpath->exp_time + MESH_PATH_EXPIRE)) { + time_after(jiffies, mpath->exp_time + MESH_PATH_EXPIRE)) { spin_unlock_bh(&mpath->state_lock); mesh_path_del(mpath->dst, mpath->sdata); } else spin_unlock_bh(&mpath->state_lock); } - read_unlock_bh(&pathtbl_resize_lock); + rcu_read_unlock(); } void mesh_pathtbl_unregister(void) { - mesh_table_free(mesh_paths, true); - mesh_table_free(mpp_paths, true); + /* no need for locking during exit path */ + mesh_table_free(rcu_dereference_raw(mesh_paths), true); + mesh_table_free(rcu_dereference_raw(mpp_paths), true); } -- 2.20.1