af_unix: Save hash in sk_hash.

To replace unix_table_lock with per-hash locks in the next patch, we need
to save a hash in each socket because /proc/net/unix or BPF prog iterate
sockets while holding a hash table lock and release it later in a different
function.

Currently, we store a real/pseudo hash in struct unix_address.  However, we
do not allocate it to unbound sockets, nor should we do just for that.  For
this purpose, we can use sk_hash.  Then, we no longer use the hash field in
struct unix_address and can remove it.

Also, this patch does
  - rename unix_insert_socket() to unix_insert_unbound_socket()
  - remove the redundant list argument from __unix_insert_socket() and
     unix_insert_unbound_socket()
  - use 'unsigned int' instead of 'unsigned' in __unix_set_addr_hash()
  - remove 'inline' from unix_remove_socket() and
     unix_insert_unbound_socket().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index 7d142e8..89049cc 100644 (file)
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -26,7 +26,6 @@ extern struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
 struct unix_address {
        refcount_t      refcnt;
        int             len;
-       unsigned int    hash;
        struct sockaddr_un name[];
 };
 

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 076d029..bd9fbfe 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -280,31 +280,33 @@ static void __unix_remove_socket(struct sock *sk)
        sk_del_node_init(sk);
 }
 
-static void __unix_insert_socket(struct hlist_head *list, struct sock *sk)
+static void __unix_insert_socket(struct sock *sk)
 {
        WARN_ON(!sk_unhashed(sk));
-       sk_add_node(sk, list);
+       sk_add_node(sk, &unix_socket_table[sk->sk_hash]);
 }
 
-static void __unix_set_addr(struct sock *sk, struct unix_address *addr,
-                           unsigned hash)
+static void __unix_set_addr_hash(struct sock *sk, struct unix_address *addr,
+                                unsigned int hash)
 {
        __unix_remove_socket(sk);
        smp_store_release(&unix_sk(sk)->addr, addr);
-       __unix_insert_socket(&unix_socket_table[hash], sk);
+
+       sk->sk_hash = hash;
+       __unix_insert_socket(sk);
 }
 
-static inline void unix_remove_socket(struct sock *sk)
+static void unix_remove_socket(struct sock *sk)
 {
        spin_lock(&unix_table_lock);
        __unix_remove_socket(sk);
        spin_unlock(&unix_table_lock);
 }
 
-static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)
+static void unix_insert_unbound_socket(struct sock *sk)
 {
        spin_lock(&unix_table_lock);
-       __unix_insert_socket(list, sk);
+       __unix_insert_socket(sk);
        spin_unlock(&unix_table_lock);
 }
 
@@ -893,6 +895,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
 
        sock_init_data(sock, sk);
 
+       sk->sk_hash             = unix_unbound_hash(sk);
        sk->sk_allocation       = GFP_KERNEL_ACCOUNT;
        sk->sk_write_space      = unix_write_space;
        sk->sk_max_ack_backlog  = net->unx.sysctl_max_dgram_qlen;
@@ -908,7 +911,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
        init_waitqueue_head(&u->peer_wait);
        init_waitqueue_func_entry(&u->peer_wake, unix_dgram_peer_wake_relay);
        memset(&u->scm_stat, 0, sizeof(struct scm_stat));
-       unix_insert_socket(&unix_socket_table[unix_unbound_hash(sk)], sk);
+       unix_insert_unbound_socket(sk);
 
        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 
@@ -1054,6 +1057,7 @@ static int unix_autobind(struct sock *sk)
        struct unix_address *addr;
        unsigned int retries = 0;
        static u32 ordernum = 1;
+       unsigned int new_hash;
        int err;
 
        err = mutex_lock_interruptible(&u->bindlock);
@@ -1075,13 +1079,13 @@ static int unix_autobind(struct sock *sk)
 retry:
        addr->len = sprintf(addr->name->sun_path + 1, "%05x", ordernum) +
                offsetof(struct sockaddr_un, sun_path) + 1;
-       addr->hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type);
 
+       new_hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type);
        spin_lock(&unix_table_lock);
        ordernum = (ordernum+1)&0xFFFFF;
 
        if (__unix_find_socket_byname(sock_net(sk), addr->name, addr->len,
-                                     addr->hash)) {
+                                     new_hash)) {
                spin_unlock(&unix_table_lock);
                /*
                 * __unix_find_socket_byname() may take long time if many names
@@ -1097,7 +1101,7 @@ retry:
                goto retry;
        }
 
-       __unix_set_addr(sk, addr, addr->hash);
+       __unix_set_addr_hash(sk, addr, new_hash);
        spin_unlock(&unix_table_lock);
        err = 0;
 
@@ -1113,9 +1117,9 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
        struct unix_sock *u = unix_sk(sk);
        struct user_namespace *ns; // barf...
        struct unix_address *addr;
+       unsigned int new_hash;
        struct dentry *dentry;
        struct path parent;
-       unsigned int hash;
        int err;
 
        unix_mkname_bsd(sunaddr, addr_len);
@@ -1151,12 +1155,11 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
        if (u->addr)
                goto out_unlock;
 
-       addr->hash = UNIX_HASH_SIZE;
-       hash = unix_bsd_hash(d_backing_inode(dentry));
+       new_hash = unix_bsd_hash(d_backing_inode(dentry));
        spin_lock(&unix_table_lock);
        u->path.mnt = mntget(parent.mnt);
        u->path.dentry = dget(dentry);
-       __unix_set_addr(sk, addr, hash);
+       __unix_set_addr_hash(sk, addr, new_hash);
        spin_unlock(&unix_table_lock);
        mutex_unlock(&u->bindlock);
        done_path_create(&parent, dentry);
@@ -1180,6 +1183,7 @@ static int unix_bind_abstract(struct sock *sk, struct sockaddr_un *sunaddr,
 {
        struct unix_sock *u = unix_sk(sk);
        struct unix_address *addr;
+       unsigned int new_hash;
        int err;
 
        addr = unix_create_addr(sunaddr, addr_len);
@@ -1195,14 +1199,14 @@ static int unix_bind_abstract(struct sock *sk, struct sockaddr_un *sunaddr,
                goto out_mutex;
        }
 
-       addr->hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type);
+       new_hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type);
        spin_lock(&unix_table_lock);
 
        if (__unix_find_socket_byname(sock_net(sk), addr->name, addr->len,
-                                     addr->hash))
+                                     new_hash))
                goto out_spin;
 
-       __unix_set_addr(sk, addr, addr->hash);
+       __unix_set_addr_hash(sk, addr, new_hash);
        spin_unlock(&unix_table_lock);
        mutex_unlock(&u->bindlock);
        return 0;