From: Johannes Berg <johannes.berg@xxxxxxxxx>
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 <johannes.berg@xxxxxxxxx>
---
net/mac80211/mesh.h | 4 -
net/mac80211/mesh_pathtbl.c | 156 +++++++++++++++++++++++++++++---------------
2 files changed, 103 insertions(+), 57 deletions(-)
--- a/net/mac80211/mesh_pathtbl.c 2011-05-14 11:06:34.000000000 +0200
+++ b/net/mac80211/mesh_pathtbl.c 2011-05-14 11:43:26.000000000 +0200
@@ -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 *ds
*/
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 ieee80
{
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 ieee80
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 ieee80
}
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 ieee80
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, struc
{
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, struc
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, struc
}
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, struc
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 *
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 *
*/
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(struc
*/
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 ieee8
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 ieee8
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;
}
@@ -745,52 +787,60 @@ static int mesh_path_node_copy(struct hl
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;
-
- mpp_paths = mesh_table_alloc(INIT_PATHS_SIZE_ORDER);
- if (!mpp_paths) {
- mesh_table_free(mesh_paths, true);
+ tbl_path->free_node = &mesh_path_node_free;
+ tbl_path->copy_node = &mesh_path_node_copy;
+ tbl_path->mean_chain_len = MEAN_CHAIN_LEN;
+
+ 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);
}
--- a/net/mac80211/mesh.h 2011-05-14 11:22:20.000000000 +0200
+++ b/net/mac80211/mesh.h 2011-05-14 11:32:33.000000000 +0200
@@ -289,10 +289,6 @@ static inline bool mesh_path_sel_is_hwmp
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);
--
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