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authorJiri Olsa <jolsa@redhat.com>2009-07-08 12:09:13 +0000
committerDavid S. Miller <davem@davemloft.net>2009-07-09 17:06:57 -0700
commita57de0b4336e48db2811a2030bb68dba8dd09d88 (patch)
treea01c189d5fd55c69c9e2e842241e84b46728bc60 /net
parentnetpoll: Fix carrier detection for drivers that are using phylib (diff)
downloadlinux-dev-a57de0b4336e48db2811a2030bb68dba8dd09d88.tar.xz
linux-dev-a57de0b4336e48db2811a2030bb68dba8dd09d88.zip
net: adding memory barrier to the poll and receive callbacks
Adding memory barrier after the poll_wait function, paired with receive callbacks. Adding fuctions sock_poll_wait and sk_has_sleeper to wrap the memory barrier. Without the memory barrier, following race can happen. The race fires, when following code paths meet, and the tp->rcv_nxt and __add_wait_queue updates stay in CPU caches. CPU1 CPU2 sys_select receive packet ... ... __add_wait_queue update tp->rcv_nxt ... ... tp->rcv_nxt check sock_def_readable ... { schedule ... if (sk->sk_sleep && waitqueue_active(sk->sk_sleep)) wake_up_interruptible(sk->sk_sleep) ... } If there was no cache the code would work ok, since the wait_queue and rcv_nxt are opposit to each other. Meaning that once tp->rcv_nxt is updated by CPU2, the CPU1 either already passed the tp->rcv_nxt check and sleeps, or will get the new value for tp->rcv_nxt and will return with new data mask. In both cases the process (CPU1) is being added to the wait queue, so the waitqueue_active (CPU2) call cannot miss and will wake up CPU1. The bad case is when the __add_wait_queue changes done by CPU1 stay in its cache, and so does the tp->rcv_nxt update on CPU2 side. The CPU1 will then endup calling schedule and sleep forever if there are no more data on the socket. Calls to poll_wait in following modules were ommited: net/bluetooth/af_bluetooth.c net/irda/af_irda.c net/irda/irnet/irnet_ppp.c net/mac80211/rc80211_pid_debugfs.c net/phonet/socket.c net/rds/af_rds.c net/rfkill/core.c net/sunrpc/cache.c net/sunrpc/rpc_pipe.c net/tipc/socket.c Signed-off-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/atm/common.c6
-rw-r--r--net/core/datagram.c2
-rw-r--r--net/core/sock.c8
-rw-r--r--net/dccp/output.c2
-rw-r--r--net/dccp/proto.c2
-rw-r--r--net/ipv4/tcp.c2
-rw-r--r--net/iucv/af_iucv.c4
-rw-r--r--net/rxrpc/af_rxrpc.c4
-rw-r--r--net/unix/af_unix.c8
9 files changed, 19 insertions, 19 deletions
diff --git a/net/atm/common.c b/net/atm/common.c
index c1c97936192c..8c4d843eb17f 100644
--- a/net/atm/common.c
+++ b/net/atm/common.c
@@ -92,7 +92,7 @@ static void vcc_sock_destruct(struct sock *sk)
static void vcc_def_wakeup(struct sock *sk)
{
read_lock(&sk->sk_callback_lock);
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up(sk->sk_sleep);
read_unlock(&sk->sk_callback_lock);
}
@@ -110,7 +110,7 @@ static void vcc_write_space(struct sock *sk)
read_lock(&sk->sk_callback_lock);
if (vcc_writable(sk)) {
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible(sk->sk_sleep);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
@@ -594,7 +594,7 @@ unsigned int vcc_poll(struct file *file, struct socket *sock, poll_table *wait)
struct atm_vcc *vcc;
unsigned int mask;
- poll_wait(file, sk->sk_sleep, wait);
+ sock_poll_wait(file, sk->sk_sleep, wait);
mask = 0;
vcc = ATM_SD(sock);
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 58abee1f1df1..b0fe69211eef 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -712,7 +712,7 @@ unsigned int datagram_poll(struct file *file, struct socket *sock,
struct sock *sk = sock->sk;
unsigned int mask;
- poll_wait(file, sk->sk_sleep, wait);
+ sock_poll_wait(file, sk->sk_sleep, wait);
mask = 0;
/* exceptional events? */
diff --git a/net/core/sock.c b/net/core/sock.c
index b0ba569bc973..6354863b1c68 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1715,7 +1715,7 @@ EXPORT_SYMBOL(sock_no_sendpage);
static void sock_def_wakeup(struct sock *sk)
{
read_lock(&sk->sk_callback_lock);
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible_all(sk->sk_sleep);
read_unlock(&sk->sk_callback_lock);
}
@@ -1723,7 +1723,7 @@ static void sock_def_wakeup(struct sock *sk)
static void sock_def_error_report(struct sock *sk)
{
read_lock(&sk->sk_callback_lock);
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible_poll(sk->sk_sleep, POLLERR);
sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR);
read_unlock(&sk->sk_callback_lock);
@@ -1732,7 +1732,7 @@ static void sock_def_error_report(struct sock *sk)
static void sock_def_readable(struct sock *sk, int len)
{
read_lock(&sk->sk_callback_lock);
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible_sync_poll(sk->sk_sleep, POLLIN |
POLLRDNORM | POLLRDBAND);
sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
@@ -1747,7 +1747,7 @@ static void sock_def_write_space(struct sock *sk)
* progress. --DaveM
*/
if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf) {
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible_sync_poll(sk->sk_sleep, POLLOUT |
POLLWRNORM | POLLWRBAND);
diff --git a/net/dccp/output.c b/net/dccp/output.c
index c0e88c16d088..c96119fda688 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -196,7 +196,7 @@ void dccp_write_space(struct sock *sk)
{
read_lock(&sk->sk_callback_lock);
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible(sk->sk_sleep);
/* Should agree with poll, otherwise some programs break */
if (sock_writeable(sk))
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 314a1b5c033c..94ca8eaace7d 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -311,7 +311,7 @@ unsigned int dccp_poll(struct file *file, struct socket *sock,
unsigned int mask;
struct sock *sk = sock->sk;
- poll_wait(file, sk->sk_sleep, wait);
+ sock_poll_wait(file, sk->sk_sleep, wait);
if (sk->sk_state == DCCP_LISTEN)
return inet_csk_listen_poll(sk);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 7870a535dac6..91145244ea63 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -339,7 +339,7 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
struct sock *sk = sock->sk;
struct tcp_sock *tp = tcp_sk(sk);
- poll_wait(file, sk->sk_sleep, wait);
+ sock_poll_wait(file, sk->sk_sleep, wait);
if (sk->sk_state == TCP_LISTEN)
return inet_csk_listen_poll(sk);
diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index 6be5f92d1094..49c15b48408e 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -306,7 +306,7 @@ static inline int iucv_below_msglim(struct sock *sk)
static void iucv_sock_wake_msglim(struct sock *sk)
{
read_lock(&sk->sk_callback_lock);
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible_all(sk->sk_sleep);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
read_unlock(&sk->sk_callback_lock);
@@ -1256,7 +1256,7 @@ unsigned int iucv_sock_poll(struct file *file, struct socket *sock,
struct sock *sk = sock->sk;
unsigned int mask = 0;
- poll_wait(file, sk->sk_sleep, wait);
+ sock_poll_wait(file, sk->sk_sleep, wait);
if (sk->sk_state == IUCV_LISTEN)
return iucv_accept_poll(sk);
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index eac5e7bb7365..bfe493ebf27c 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -63,7 +63,7 @@ static void rxrpc_write_space(struct sock *sk)
_enter("%p", sk);
read_lock(&sk->sk_callback_lock);
if (rxrpc_writable(sk)) {
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible(sk->sk_sleep);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
}
@@ -588,7 +588,7 @@ static unsigned int rxrpc_poll(struct file *file, struct socket *sock,
unsigned int mask;
struct sock *sk = sock->sk;
- poll_wait(file, sk->sk_sleep, wait);
+ sock_poll_wait(file, sk->sk_sleep, wait);
mask = 0;
/* the socket is readable if there are any messages waiting on the Rx
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 36d4e44d6233..fc3ebb906911 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -315,7 +315,7 @@ static void unix_write_space(struct sock *sk)
{
read_lock(&sk->sk_callback_lock);
if (unix_writable(sk)) {
- if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
+ if (sk_has_sleeper(sk))
wake_up_interruptible_sync(sk->sk_sleep);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
}
@@ -1985,7 +1985,7 @@ static unsigned int unix_poll(struct file *file, struct socket *sock, poll_table
struct sock *sk = sock->sk;
unsigned int mask;
- poll_wait(file, sk->sk_sleep, wait);
+ sock_poll_wait(file, sk->sk_sleep, wait);
mask = 0;
/* exceptional events? */
@@ -2022,7 +2022,7 @@ static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
struct sock *sk = sock->sk, *other;
unsigned int mask, writable;
- poll_wait(file, sk->sk_sleep, wait);
+ sock_poll_wait(file, sk->sk_sleep, wait);
mask = 0;
/* exceptional events? */
@@ -2053,7 +2053,7 @@ static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
other = unix_peer_get(sk);
if (other) {
if (unix_peer(other) != sk) {
- poll_wait(file, &unix_sk(other)->peer_wait,
+ sock_poll_wait(file, &unix_sk(other)->peer_wait,
wait);
if (unix_recvq_full(other))
writable = 0;