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[AF_UNIX]: Use spinlock for unix_table_lock
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This lock is actually taken mostly as a writer,
so using a rwlock actually just makes performance
worse especially on chips like the Intel P4.

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller authored and David S. Miller committed Jan 3, 2006
1 parent d83d846 commit fbe9cc4
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Showing 3 changed files with 20 additions and 20 deletions.
2 changes: 1 addition & 1 deletion include/net/af_unix.h
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ extern void unix_gc(void);
#define UNIX_HASH_SIZE 256

extern struct hlist_head unix_socket_table[UNIX_HASH_SIZE + 1];
extern rwlock_t unix_table_lock;
extern spinlock_t unix_table_lock;

extern atomic_t unix_tot_inflight;

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34 changes: 17 additions & 17 deletions net/unix/af_unix.c
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Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,7 @@
int sysctl_unix_max_dgram_qlen = 10;

struct hlist_head unix_socket_table[UNIX_HASH_SIZE + 1];
DEFINE_RWLOCK(unix_table_lock);
DEFINE_SPINLOCK(unix_table_lock);
static atomic_t unix_nr_socks = ATOMIC_INIT(0);

#define unix_sockets_unbound (&unix_socket_table[UNIX_HASH_SIZE])
Expand All @@ -130,7 +130,7 @@ static atomic_t unix_nr_socks = ATOMIC_INIT(0);

/*
* SMP locking strategy:
* hash table is protected with rwlock unix_table_lock
* hash table is protected with spinlock unix_table_lock
* each socket state is protected by separate rwlock.
*/

Expand Down Expand Up @@ -214,16 +214,16 @@ static void __unix_insert_socket(struct hlist_head *list, struct sock *sk)

static inline void unix_remove_socket(struct sock *sk)
{
write_lock(&unix_table_lock);
spin_lock(&unix_table_lock);
__unix_remove_socket(sk);
write_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);
}

static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)
{
write_lock(&unix_table_lock);
spin_lock(&unix_table_lock);
__unix_insert_socket(list, sk);
write_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);
}

static struct sock *__unix_find_socket_byname(struct sockaddr_un *sunname,
Expand All @@ -250,11 +250,11 @@ static inline struct sock *unix_find_socket_byname(struct sockaddr_un *sunname,
{
struct sock *s;

read_lock(&unix_table_lock);
spin_lock(&unix_table_lock);
s = __unix_find_socket_byname(sunname, len, type, hash);
if (s)
sock_hold(s);
read_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);
return s;
}

Expand All @@ -263,7 +263,7 @@ static struct sock *unix_find_socket_byinode(struct inode *i)
struct sock *s;
struct hlist_node *node;

read_lock(&unix_table_lock);
spin_lock(&unix_table_lock);
sk_for_each(s, node,
&unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
struct dentry *dentry = unix_sk(s)->dentry;
Expand All @@ -276,7 +276,7 @@ static struct sock *unix_find_socket_byinode(struct inode *i)
}
s = NULL;
found:
read_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);
return s;
}

Expand Down Expand Up @@ -642,12 +642,12 @@ static int unix_autobind(struct socket *sock)
addr->len = sprintf(addr->name->sun_path+1, "%05x", ordernum) + 1 + sizeof(short);
addr->hash = unix_hash_fold(csum_partial((void*)addr->name, addr->len, 0));

write_lock(&unix_table_lock);
spin_lock(&unix_table_lock);
ordernum = (ordernum+1)&0xFFFFF;

if (__unix_find_socket_byname(addr->name, addr->len, sock->type,
addr->hash)) {
write_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);
/* Sanity yield. It is unusual case, but yet... */
if (!(ordernum&0xFF))
yield();
Expand All @@ -658,7 +658,7 @@ static int unix_autobind(struct socket *sock)
__unix_remove_socket(sk);
u->addr = addr;
__unix_insert_socket(&unix_socket_table[addr->hash], sk);
write_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);
err = 0;

out: up(&u->readsem);
Expand Down Expand Up @@ -791,7 +791,7 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
addr->hash = UNIX_HASH_SIZE;
}

write_lock(&unix_table_lock);
spin_lock(&unix_table_lock);

if (!sunaddr->sun_path[0]) {
err = -EADDRINUSE;
Expand All @@ -814,7 +814,7 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
__unix_insert_socket(list, sk);

out_unlock:
write_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);
out_up:
up(&u->readsem);
out:
Expand Down Expand Up @@ -1916,7 +1916,7 @@ static struct sock *unix_seq_idx(int *iter, loff_t pos)

static void *unix_seq_start(struct seq_file *seq, loff_t *pos)
{
read_lock(&unix_table_lock);
spin_lock(&unix_table_lock);
return *pos ? unix_seq_idx(seq->private, *pos - 1) : ((void *) 1);
}

Expand All @@ -1931,7 +1931,7 @@ static void *unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)

static void unix_seq_stop(struct seq_file *seq, void *v)
{
read_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);
}

static int unix_seq_show(struct seq_file *seq, void *v)
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4 changes: 2 additions & 2 deletions net/unix/garbage.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -182,7 +182,7 @@ void unix_gc(void)
if (down_trylock(&unix_gc_sem))
return;

read_lock(&unix_table_lock);
spin_lock(&unix_table_lock);

forall_unix_sockets(i, s)
{
Expand Down Expand Up @@ -301,7 +301,7 @@ void unix_gc(void)
}
u->gc_tree = GC_ORPHAN;
}
read_unlock(&unix_table_lock);
spin_unlock(&unix_table_lock);

/*
* Here we are. Hitlist is filled. Die.
Expand Down

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