net: sock_def_readable() and friends RCU conversion
sk_callback_lock rwlock actually protects sk->sk_sleep pointer, so we
need two atomic operations (and associated dirtying) per incoming
packet.
RCU conversion is pretty much needed :
1) Add a new structure, called "struct socket_wq" to hold all fields
that will need rcu_read_lock() protection (currently: a
wait_queue_head_t and a struct fasync_struct pointer).
[Future patch will add a list anchor for wakeup coalescing]
2) Attach one of such structure to each "struct socket" created in
sock_alloc_inode().
3) Respect RCU grace period when freeing a "struct socket_wq"
4) Change sk_sleep pointer in "struct sock" by sk_wq, pointer to "struct
socket_wq"
5) Change sk_sleep() function to use new sk->sk_wq instead of
sk->sk_sleep
6) Change sk_has_sleeper() to wq_has_sleeper() that must be used inside
a rcu_read_lock() section.
7) Change all sk_has_sleeper() callers to :
- Use rcu_read_lock() instead of read_lock(&sk->sk_callback_lock)
- Use wq_has_sleeper() to eventually wakeup tasks.
- Use rcu_read_unlock() instead of read_unlock(&sk->sk_callback_lock)
8) sock_wake_async() is modified to use rcu protection as well.
9) Exceptions :
macvtap, drivers/net/tun.c, af_unix use integrated "struct socket_wq"
instead of dynamically allocated ones. They dont need rcu freeing.
Some cleanups or followups are probably needed, (possible
sk_callback_lock conversion to a spinlock for example...).
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/atm/common.c b/net/atm/common.c
index e3e10e6..b43feb1 100644
--- a/net/atm/common.c
+++ b/net/atm/common.c
@@ -90,10 +90,13 @@
static void vcc_def_wakeup(struct sock *sk)
{
- read_lock(&sk->sk_callback_lock);
- if (sk_has_sleeper(sk))
- wake_up(sk_sleep(sk));
- read_unlock(&sk->sk_callback_lock);
+ struct socket_wq *wq;
+
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up(&wq->wait);
+ rcu_read_unlock();
}
static inline int vcc_writable(struct sock *sk)
@@ -106,16 +109,19 @@
static void vcc_write_space(struct sock *sk)
{
- read_lock(&sk->sk_callback_lock);
+ struct socket_wq *wq;
+
+ rcu_read_lock();
if (vcc_writable(sk)) {
- if (sk_has_sleeper(sk))
- wake_up_interruptible(sk_sleep(sk));
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible(&wq->wait);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
}
- read_unlock(&sk->sk_callback_lock);
+ rcu_read_unlock();
}
static struct proto vcc_proto = {
diff --git a/net/core/sock.c b/net/core/sock.c
index 5104175..94c4aff 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1211,7 +1211,7 @@
*/
sk_refcnt_debug_inc(newsk);
sk_set_socket(newsk, NULL);
- newsk->sk_sleep = NULL;
+ newsk->sk_wq = NULL;
if (newsk->sk_prot->sockets_allocated)
percpu_counter_inc(newsk->sk_prot->sockets_allocated);
@@ -1800,41 +1800,53 @@
static void sock_def_wakeup(struct sock *sk)
{
- read_lock(&sk->sk_callback_lock);
- if (sk_has_sleeper(sk))
- wake_up_interruptible_all(sk_sleep(sk));
- read_unlock(&sk->sk_callback_lock);
+ struct socket_wq *wq;
+
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible_all(&wq->wait);
+ rcu_read_unlock();
}
static void sock_def_error_report(struct sock *sk)
{
- read_lock(&sk->sk_callback_lock);
- if (sk_has_sleeper(sk))
- wake_up_interruptible_poll(sk_sleep(sk), POLLERR);
+ struct socket_wq *wq;
+
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible_poll(&wq->wait, POLLERR);
sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR);
- read_unlock(&sk->sk_callback_lock);
+ rcu_read_unlock();
}
static void sock_def_readable(struct sock *sk, int len)
{
- read_lock(&sk->sk_callback_lock);
- if (sk_has_sleeper(sk))
- wake_up_interruptible_sync_poll(sk_sleep(sk), POLLIN |
+ struct socket_wq *wq;
+
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible_sync_poll(&wq->wait, POLLIN |
POLLRDNORM | POLLRDBAND);
sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
- read_unlock(&sk->sk_callback_lock);
+ rcu_read_unlock();
}
static void sock_def_write_space(struct sock *sk)
{
- read_lock(&sk->sk_callback_lock);
+ struct socket_wq *wq;
+
+ rcu_read_lock();
/* Do not wake up a writer until he can make "significant"
* progress. --DaveM
*/
if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf) {
- if (sk_has_sleeper(sk))
- wake_up_interruptible_sync_poll(sk_sleep(sk), POLLOUT |
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible_sync_poll(&wq->wait, POLLOUT |
POLLWRNORM | POLLWRBAND);
/* Should agree with poll, otherwise some programs break */
@@ -1842,7 +1854,7 @@
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
}
- read_unlock(&sk->sk_callback_lock);
+ rcu_read_unlock();
}
static void sock_def_destruct(struct sock *sk)
@@ -1896,10 +1908,10 @@
if (sock) {
sk->sk_type = sock->type;
- sk->sk_sleep = &sock->wait;
+ sk->sk_wq = sock->wq;
sock->sk = sk;
} else
- sk->sk_sleep = NULL;
+ sk->sk_wq = NULL;
spin_lock_init(&sk->sk_dst_lock);
rwlock_init(&sk->sk_callback_lock);
diff --git a/net/core/stream.c b/net/core/stream.c
index 7b3c3f3..cc196f42b 100644
--- a/net/core/stream.c
+++ b/net/core/stream.c
@@ -28,15 +28,19 @@
void sk_stream_write_space(struct sock *sk)
{
struct socket *sock = sk->sk_socket;
+ struct socket_wq *wq;
if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock) {
clear_bit(SOCK_NOSPACE, &sock->flags);
- if (sk_sleep(sk) && waitqueue_active(sk_sleep(sk)))
- wake_up_interruptible_poll(sk_sleep(sk), POLLOUT |
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible_poll(&wq->wait, POLLOUT |
POLLWRNORM | POLLWRBAND);
- if (sock->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
+ if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT);
+ rcu_read_unlock();
}
}
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 2d3dcb3..aadbdb5 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -195,15 +195,17 @@
void dccp_write_space(struct sock *sk)
{
- read_lock(&sk->sk_callback_lock);
+ struct socket_wq *wq;
- if (sk_has_sleeper(sk))
- wake_up_interruptible(sk_sleep(sk));
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible(&wq->wait);
/* Should agree with poll, otherwise some programs break */
if (sock_writeable(sk))
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
- read_unlock(&sk->sk_callback_lock);
+ rcu_read_unlock();
}
/**
diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 9636b7d..8be324f 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -305,11 +305,14 @@
*/
static void iucv_sock_wake_msglim(struct sock *sk)
{
- read_lock(&sk->sk_callback_lock);
- if (sk_has_sleeper(sk))
- wake_up_interruptible_all(sk_sleep(sk));
+ struct socket_wq *wq;
+
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible_all(&wq->wait);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
- read_unlock(&sk->sk_callback_lock);
+ rcu_read_unlock();
}
/* Timers */
diff --git a/net/phonet/pep.c b/net/phonet/pep.c
index e2a9576..af4d38b 100644
--- a/net/phonet/pep.c
+++ b/net/phonet/pep.c
@@ -664,12 +664,12 @@
if (signal_pending(tsk))
return sock_intr_errno(timeo);
- prepare_to_wait_exclusive(&sk->sk_socket->wait, &wait,
+ prepare_to_wait_exclusive(sk_sleep(sk), &wait,
TASK_INTERRUPTIBLE);
release_sock(sk);
timeo = schedule_timeout(timeo);
lock_sock(sk);
- finish_wait(&sk->sk_socket->wait, &wait);
+ finish_wait(sk_sleep(sk), &wait);
}
return 0;
@@ -910,10 +910,10 @@
goto out;
}
- prepare_to_wait(&sk->sk_socket->wait, &wait,
+ prepare_to_wait(sk_sleep(sk), &wait,
TASK_INTERRUPTIBLE);
done = sk_wait_event(sk, &timeo, atomic_read(&pn->tx_credits));
- finish_wait(&sk->sk_socket->wait, &wait);
+ finish_wait(sk_sleep(sk), &wait);
if (sk->sk_state != TCP_ESTABLISHED)
goto disabled;
diff --git a/net/phonet/socket.c b/net/phonet/socket.c
index c785bfd..6e9848bf 100644
--- a/net/phonet/socket.c
+++ b/net/phonet/socket.c
@@ -265,7 +265,7 @@
struct pep_sock *pn = pep_sk(sk);
unsigned int mask = 0;
- poll_wait(file, &sock->wait, wait);
+ poll_wait(file, sk_sleep(sk), wait);
switch (sk->sk_state) {
case TCP_LISTEN:
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index c432d76..0b9bb20 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -62,13 +62,15 @@
static void rxrpc_write_space(struct sock *sk)
{
_enter("%p", sk);
- read_lock(&sk->sk_callback_lock);
+ rcu_read_lock();
if (rxrpc_writable(sk)) {
- if (sk_has_sleeper(sk))
- wake_up_interruptible(sk_sleep(sk));
+ struct socket_wq *wq = rcu_dereference(sk->sk_wq);
+
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible(&wq->wait);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
}
- read_unlock(&sk->sk_callback_lock);
+ rcu_read_unlock();
}
/*
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 13d8229..d54700a 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -6065,7 +6065,7 @@
* here by modeling from the current TCP/UDP code.
* We have not tested with it yet.
*/
- if (sock->fasync_list &&
+ if (sock->wq->fasync_list &&
!(sk->sk_shutdown & SEND_SHUTDOWN))
sock_wake_async(sock,
SOCK_WAKE_SPACE, POLL_OUT);
diff --git a/net/socket.c b/net/socket.c
index cb7c1f6..dae8c6b 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -252,9 +252,14 @@
ei = kmem_cache_alloc(sock_inode_cachep, GFP_KERNEL);
if (!ei)
return NULL;
- init_waitqueue_head(&ei->socket.wait);
+ ei->socket.wq = kmalloc(sizeof(struct socket_wq), GFP_KERNEL);
+ if (!ei->socket.wq) {
+ kmem_cache_free(sock_inode_cachep, ei);
+ return NULL;
+ }
+ init_waitqueue_head(&ei->socket.wq->wait);
+ ei->socket.wq->fasync_list = NULL;
- ei->socket.fasync_list = NULL;
ei->socket.state = SS_UNCONNECTED;
ei->socket.flags = 0;
ei->socket.ops = NULL;
@@ -264,10 +269,21 @@
return &ei->vfs_inode;
}
+
+static void wq_free_rcu(struct rcu_head *head)
+{
+ struct socket_wq *wq = container_of(head, struct socket_wq, rcu);
+
+ kfree(wq);
+}
+
static void sock_destroy_inode(struct inode *inode)
{
- kmem_cache_free(sock_inode_cachep,
- container_of(inode, struct socket_alloc, vfs_inode));
+ struct socket_alloc *ei;
+
+ ei = container_of(inode, struct socket_alloc, vfs_inode);
+ call_rcu(&ei->socket.wq->rcu, wq_free_rcu);
+ kmem_cache_free(sock_inode_cachep, ei);
}
static void init_once(void *foo)
@@ -513,7 +529,7 @@
module_put(owner);
}
- if (sock->fasync_list)
+ if (sock->wq->fasync_list)
printk(KERN_ERR "sock_release: fasync list not empty!\n");
percpu_sub(sockets_in_use, 1);
@@ -1080,9 +1096,9 @@
lock_sock(sk);
- fasync_helper(fd, filp, on, &sock->fasync_list);
+ fasync_helper(fd, filp, on, &sock->wq->fasync_list);
- if (!sock->fasync_list)
+ if (!sock->wq->fasync_list)
sock_reset_flag(sk, SOCK_FASYNC);
else
sock_set_flag(sk, SOCK_FASYNC);
@@ -1091,12 +1107,20 @@
return 0;
}
-/* This function may be called only under socket lock or callback_lock */
+/* This function may be called only under socket lock or callback_lock or rcu_lock */
int sock_wake_async(struct socket *sock, int how, int band)
{
- if (!sock || !sock->fasync_list)
+ struct socket_wq *wq;
+
+ if (!sock)
return -1;
+ rcu_read_lock();
+ wq = rcu_dereference(sock->wq);
+ if (!wq || !wq->fasync_list) {
+ rcu_read_unlock();
+ return -1;
+ }
switch (how) {
case SOCK_WAKE_WAITD:
if (test_bit(SOCK_ASYNC_WAITDATA, &sock->flags))
@@ -1108,11 +1132,12 @@
/* fall through */
case SOCK_WAKE_IO:
call_kill:
- kill_fasync(&sock->fasync_list, SIGIO, band);
+ kill_fasync(&wq->fasync_list, SIGIO, band);
break;
case SOCK_WAKE_URG:
- kill_fasync(&sock->fasync_list, SIGURG, band);
+ kill_fasync(&wq->fasync_list, SIGURG, band);
}
+ rcu_read_unlock();
return 0;
}
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 87c0360..fef2cc5 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -313,13 +313,16 @@
static void unix_write_space(struct sock *sk)
{
- read_lock(&sk->sk_callback_lock);
+ struct socket_wq *wq;
+
+ rcu_read_lock();
if (unix_writable(sk)) {
- if (sk_has_sleeper(sk))
- wake_up_interruptible_sync(sk_sleep(sk));
+ wq = rcu_dereference(sk->sk_wq);
+ if (wq_has_sleeper(wq))
+ wake_up_interruptible_sync(&wq->wait);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
}
- read_unlock(&sk->sk_callback_lock);
+ rcu_read_unlock();
}
/* When dgram socket disconnects (or changes its peer), we clear its receive
@@ -406,9 +409,7 @@
skpair->sk_err = ECONNRESET;
unix_state_unlock(skpair);
skpair->sk_state_change(skpair);
- read_lock(&skpair->sk_callback_lock);
sk_wake_async(skpair, SOCK_WAKE_WAITD, POLL_HUP);
- read_unlock(&skpair->sk_callback_lock);
}
sock_put(skpair); /* It may now die */
unix_peer(sk) = NULL;
@@ -1142,7 +1143,7 @@
newsk->sk_peercred.pid = task_tgid_vnr(current);
current_euid_egid(&newsk->sk_peercred.uid, &newsk->sk_peercred.gid);
newu = unix_sk(newsk);
- newsk->sk_sleep = &newu->peer_wait;
+ newsk->sk_wq = &newu->peer_wq;
otheru = unix_sk(other);
/* copy address information from listening to new sock*/
@@ -1931,12 +1932,10 @@
other->sk_shutdown |= peer_mode;
unix_state_unlock(other);
other->sk_state_change(other);
- read_lock(&other->sk_callback_lock);
if (peer_mode == SHUTDOWN_MASK)
sk_wake_async(other, SOCK_WAKE_WAITD, POLL_HUP);
else if (peer_mode & RCV_SHUTDOWN)
sk_wake_async(other, SOCK_WAKE_WAITD, POLL_IN);
- read_unlock(&other->sk_callback_lock);
}
if (other)
sock_put(other);