From 81e2a3d5b75cbf0b42428b9d5a7cc7c85be9e7a7 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 17 Jun 2009 19:06:12 -0700 Subject: atm: sk_wmem_alloc initial value is one commit 2b85a34e911bf483c27cfdd124aeb1605145dc80 (net: No more expensive sock_hold()/sock_put() on each tx) changed initial sk_wmem_alloc value. This broke net/atm since this protocol assumed a null initial value. This patch makes necessary changes. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/atm/common.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'net/atm/common.c') diff --git a/net/atm/common.c b/net/atm/common.c index d34edbe754c8..c1c97936192c 100644 --- a/net/atm/common.c +++ b/net/atm/common.c @@ -62,15 +62,15 @@ static struct sk_buff *alloc_tx(struct atm_vcc *vcc,unsigned int size) struct sk_buff *skb; struct sock *sk = sk_atm(vcc); - if (atomic_read(&sk->sk_wmem_alloc) && !atm_may_send(vcc, size)) { + if (sk_wmem_alloc_get(sk) && !atm_may_send(vcc, size)) { pr_debug("Sorry: wmem_alloc = %d, size = %d, sndbuf = %d\n", - atomic_read(&sk->sk_wmem_alloc), size, + sk_wmem_alloc_get(sk), size, sk->sk_sndbuf); return NULL; } - while (!(skb = alloc_skb(size,GFP_KERNEL))) schedule(); - pr_debug("AlTx %d += %d\n", atomic_read(&sk->sk_wmem_alloc), - skb->truesize); + while (!(skb = alloc_skb(size, GFP_KERNEL))) + schedule(); + pr_debug("AlTx %d += %d\n", sk_wmem_alloc_get(sk), skb->truesize); atomic_add(skb->truesize, &sk->sk_wmem_alloc); return skb; } @@ -145,7 +145,7 @@ int vcc_create(struct net *net, struct socket *sock, int protocol, int family) memset(&vcc->local,0,sizeof(struct sockaddr_atmsvc)); memset(&vcc->remote,0,sizeof(struct sockaddr_atmsvc)); vcc->qos.txtp.max_sdu = 1 << 16; /* for meta VCs */ - atomic_set(&sk->sk_wmem_alloc, 0); + atomic_set(&sk->sk_wmem_alloc, 1); atomic_set(&sk->sk_rmem_alloc, 0); vcc->push = NULL; vcc->pop = NULL; -- cgit v1.2.3 From a57de0b4336e48db2811a2030bb68dba8dd09d88 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 8 Jul 2009 12:09:13 +0000 Subject: 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 Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/atm/common.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'net/atm/common.c') 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); -- cgit v1.2.3