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af_unix: Put a socket into a per-netns hash table.
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This commit replaces the global hash table with a per-netns one and removes
the global one.

We now link a socket in each netns's hash table so we can save some netns
comparisons when iterating through a hash bucket.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Kuniyuki Iwashima authored and David S. Miller committed Jun 22, 2022
1 parent 79b05be commit cf2f225
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Showing 3 changed files with 23 additions and 37 deletions.
1 change: 0 additions & 1 deletion include/net/af_unix.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,6 @@ struct sock *unix_peer_get(struct sock *sk);

extern unsigned int unix_tot_inflight;
extern spinlock_t unix_table_locks[UNIX_HASH_SIZE];
extern struct hlist_head unix_socket_table[UNIX_HASH_SIZE];

struct unix_address {
refcount_t refcnt;
Expand Down
50 changes: 20 additions & 30 deletions net/unix/af_unix.c
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Original file line number Diff line number Diff line change
Expand Up @@ -120,8 +120,6 @@

spinlock_t unix_table_locks[UNIX_HASH_SIZE];
EXPORT_SYMBOL_GPL(unix_table_locks);
struct hlist_head unix_socket_table[UNIX_HASH_SIZE];
EXPORT_SYMBOL_GPL(unix_socket_table);
static atomic_long_t unix_nr_socks;

/* SMP locking strategy:
Expand Down Expand Up @@ -308,20 +306,20 @@ static void __unix_remove_socket(struct sock *sk)
sk_del_node_init(sk);
}

static void __unix_insert_socket(struct sock *sk)
static void __unix_insert_socket(struct net *net, struct sock *sk)
{
DEBUG_NET_WARN_ON_ONCE(!sk_unhashed(sk));
sk_add_node(sk, &unix_socket_table[sk->sk_hash]);
sk_add_node(sk, &net->unx.table.buckets[sk->sk_hash]);
}

static void __unix_set_addr_hash(struct sock *sk, struct unix_address *addr,
unsigned int hash)
static void __unix_set_addr_hash(struct net *net, struct sock *sk,
struct unix_address *addr, unsigned int hash)
{
__unix_remove_socket(sk);
smp_store_release(&unix_sk(sk)->addr, addr);

sk->sk_hash = hash;
__unix_insert_socket(sk);
__unix_insert_socket(net, sk);
}

static void unix_remove_socket(struct net *net, struct sock *sk)
Expand All @@ -337,7 +335,7 @@ static void unix_insert_unbound_socket(struct net *net, struct sock *sk)
{
spin_lock(&unix_table_locks[sk->sk_hash]);
spin_lock(&net->unx.table.locks[sk->sk_hash]);
__unix_insert_socket(sk);
__unix_insert_socket(net, sk);
spin_unlock(&net->unx.table.locks[sk->sk_hash]);
spin_unlock(&unix_table_locks[sk->sk_hash]);
}
Expand All @@ -348,12 +346,9 @@ static struct sock *__unix_find_socket_byname(struct net *net,
{
struct sock *s;

sk_for_each(s, &unix_socket_table[hash]) {
sk_for_each(s, &net->unx.table.buckets[hash]) {
struct unix_sock *u = unix_sk(s);

if (!net_eq(sock_net(s), net))
continue;

if (u->addr->len == len &&
!memcmp(u->addr->name, sunname, len))
return s;
Expand Down Expand Up @@ -384,7 +379,7 @@ static struct sock *unix_find_socket_byinode(struct net *net, struct inode *i)

spin_lock(&unix_table_locks[hash]);
spin_lock(&net->unx.table.locks[hash]);
sk_for_each(s, &unix_socket_table[hash]) {
sk_for_each(s, &net->unx.table.buckets[hash]) {
struct dentry *dentry = unix_sk(s)->path.dentry;

if (dentry && d_backing_inode(dentry) == i) {
Expand Down Expand Up @@ -1140,7 +1135,7 @@ static int unix_autobind(struct sock *sk)
goto retry;
}

__unix_set_addr_hash(sk, addr, new_hash);
__unix_set_addr_hash(net, sk, addr, new_hash);
unix_table_double_unlock(net, old_hash, new_hash);
err = 0;

Expand Down Expand Up @@ -1199,7 +1194,7 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
unix_table_double_lock(net, old_hash, new_hash);
u->path.mnt = mntget(parent.mnt);
u->path.dentry = dget(dentry);
__unix_set_addr_hash(sk, addr, new_hash);
__unix_set_addr_hash(net, sk, addr, new_hash);
unix_table_double_unlock(net, old_hash, new_hash);
mutex_unlock(&u->bindlock);
done_path_create(&parent, dentry);
Expand Down Expand Up @@ -1246,7 +1241,7 @@ static int unix_bind_abstract(struct sock *sk, struct sockaddr_un *sunaddr,
if (__unix_find_socket_byname(net, addr->name, addr->len, new_hash))
goto out_spin;

__unix_set_addr_hash(sk, addr, new_hash);
__unix_set_addr_hash(net, sk, addr, new_hash);
unix_table_double_unlock(net, old_hash, new_hash);
mutex_unlock(&u->bindlock);
return 0;
Expand Down Expand Up @@ -3239,12 +3234,11 @@ static struct sock *unix_from_bucket(struct seq_file *seq, loff_t *pos)
{
unsigned long offset = get_offset(*pos);
unsigned long bucket = get_bucket(*pos);
struct sock *sk;
unsigned long count = 0;
struct sock *sk;

for (sk = sk_head(&unix_socket_table[bucket]); sk; sk = sk_next(sk)) {
if (sock_net(sk) != seq_file_net(seq))
continue;
for (sk = sk_head(&seq_file_net(seq)->unx.table.buckets[bucket]);
sk; sk = sk_next(sk)) {
if (++count == offset)
break;
}
Expand Down Expand Up @@ -3279,13 +3273,13 @@ static struct sock *unix_get_next(struct seq_file *seq, struct sock *sk,
loff_t *pos)
{
unsigned long bucket = get_bucket(*pos);
struct net *net = seq_file_net(seq);

for (sk = sk_next(sk); sk; sk = sk_next(sk))
if (sock_net(sk) == net)
return sk;
sk = sk_next(sk);
if (sk)
return sk;


spin_unlock(&net->unx.table.locks[bucket]);
spin_unlock(&seq_file_net(seq)->unx.table.locks[bucket]);
spin_unlock(&unix_table_locks[bucket]);

*pos = set_bucket_offset(++bucket, 1);
Expand Down Expand Up @@ -3406,17 +3400,13 @@ static int bpf_iter_unix_hold_batch(struct seq_file *seq, struct sock *start_sk)

{
struct bpf_unix_iter_state *iter = seq->private;
struct net *net = seq_file_net(seq);
unsigned int expected = 1;
struct sock *sk;

sock_hold(start_sk);
iter->batch[iter->end_sk++] = start_sk;

for (sk = sk_next(start_sk); sk; sk = sk_next(sk)) {
if (sock_net(sk) != net)
continue;

if (iter->end_sk < iter->max_sk) {
sock_hold(sk);
iter->batch[iter->end_sk++] = sk;
Expand All @@ -3425,7 +3415,7 @@ static int bpf_iter_unix_hold_batch(struct seq_file *seq, struct sock *start_sk)
expected++;
}

spin_unlock(&net->unx.table.locks[start_sk->sk_hash]);
spin_unlock(&seq_file_net(seq)->unx.table.locks[start_sk->sk_hash]);
spin_unlock(&unix_table_locks[start_sk->sk_hash]);

return expected;
Expand Down
9 changes: 3 additions & 6 deletions net/unix/diag.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -210,9 +210,7 @@ static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
num = 0;
spin_lock(&unix_table_locks[slot]);
spin_lock(&net->unx.table.locks[slot]);
sk_for_each(sk, &unix_socket_table[slot]) {
if (!net_eq(sock_net(sk), net))
continue;
sk_for_each(sk, &net->unx.table.buckets[slot]) {
if (num < s_num)
goto next;
if (!(req->udiag_states & (1 << sk->sk_state)))
Expand Down Expand Up @@ -246,13 +244,14 @@ static struct sock *unix_lookup_by_ino(struct net *net, unsigned int ino)
for (i = 0; i < UNIX_HASH_SIZE; i++) {
spin_lock(&unix_table_locks[i]);
spin_lock(&net->unx.table.locks[i]);
sk_for_each(sk, &unix_socket_table[i])
sk_for_each(sk, &net->unx.table.buckets[i]) {
if (ino == sock_i_ino(sk)) {
sock_hold(sk);
spin_unlock(&net->unx.table.locks[i]);
spin_unlock(&unix_table_locks[i]);
return sk;
}
}
spin_unlock(&net->unx.table.locks[i]);
spin_unlock(&unix_table_locks[i]);
}
Expand All @@ -277,8 +276,6 @@ static int unix_diag_get_exact(struct sk_buff *in_skb,
err = -ENOENT;
if (sk == NULL)
goto out_nosk;
if (!net_eq(sock_net(sk), net))
goto out;

err = sock_diag_check_cookie(sk, req->udiag_cookie);
if (err)
Expand Down

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