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Phonet: use atomic for packet TX window
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GPRS TX flow control won't need to lock the underlying socket anymore.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Rémi Denis-Courmont authored and David S. Miller committed Dec 17, 2008
1 parent 57c81ff commit be67773
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Showing 3 changed files with 23 additions and 19 deletions.
2 changes: 1 addition & 1 deletion include/net/phonet/pep.h
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Original file line number Diff line number Diff line change
Expand Up @@ -35,12 +35,12 @@ struct pep_sock {
struct sock *listener;
struct sk_buff_head ctrlreq_queue;
#define PNPIPE_CTRLREQ_MAX 10
atomic_t tx_credits;
int ifindex;
u16 peer_type; /* peer type/subtype */
u8 pipe_handle;

u8 rx_credits;
u8 tx_credits;
u8 rx_fc; /* RX flow control */
u8 tx_fc; /* TX flow control */
u8 init_enable; /* auto-enable at creation */
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38 changes: 21 additions & 17 deletions net/phonet/pep.c
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Original file line number Diff line number Diff line change
Expand Up @@ -225,6 +225,7 @@ static int pipe_rcv_status(struct sock *sk, struct sk_buff *skb)
{
struct pep_sock *pn = pep_sk(sk);
struct pnpipehdr *hdr = pnp_hdr(skb);
int wake = 0;

if (!pskb_may_pull(skb, sizeof(*hdr) + 4))
return -EINVAL;
Expand All @@ -241,35 +242,32 @@ static int pipe_rcv_status(struct sock *sk, struct sk_buff *skb)
case PN_LEGACY_FLOW_CONTROL:
switch (hdr->data[4]) {
case PEP_IND_BUSY:
pn->tx_credits = 0;
atomic_set(&pn->tx_credits, 0);
break;
case PEP_IND_READY:
pn->tx_credits = 1;
atomic_set(&pn->tx_credits, wake = 1);
break;
}
break;
case PN_ONE_CREDIT_FLOW_CONTROL:
if (hdr->data[4] == PEP_IND_READY)
pn->tx_credits = 1;
atomic_set(&pn->tx_credits, wake = 1);
break;
}
break;

case PN_PEP_IND_ID_MCFC_GRANT_CREDITS:
if (pn->tx_fc != PN_MULTI_CREDIT_FLOW_CONTROL)
break;
if (pn->tx_credits + hdr->data[4] > 0xff)
pn->tx_credits = 0xff;
else
pn->tx_credits += hdr->data[4];
atomic_add(wake = hdr->data[4], &pn->tx_credits);
break;

default:
LIMIT_NETDEBUG(KERN_DEBUG"Phonet unknown PEP indication: %u\n",
(unsigned)hdr->data[1]);
return -EOPNOTSUPP;
}
if (pn->tx_credits)
if (wake)
sk->sk_write_space(sk);
return 0;
}
Expand Down Expand Up @@ -343,7 +341,7 @@ static int pipe_do_rcv(struct sock *sk, struct sk_buff *skb)
}
/* fall through */
case PNS_PEP_DISABLE_REQ:
pn->tx_credits = 0;
atomic_set(&pn->tx_credits, 0);
pep_reply(sk, skb, PN_PIPE_NO_ERROR, NULL, 0, GFP_ATOMIC);
break;

Expand Down Expand Up @@ -390,7 +388,7 @@ static int pipe_do_rcv(struct sock *sk, struct sk_buff *skb)
/* fall through */
case PNS_PIPE_ENABLED_IND:
if (!pn_flow_safe(pn->tx_fc)) {
pn->tx_credits = 1;
atomic_set(&pn->tx_credits, 1);
sk->sk_write_space(sk);
}
if (sk->sk_state == TCP_ESTABLISHED)
Expand Down Expand Up @@ -504,8 +502,9 @@ static int pep_connreq_rcv(struct sock *sk, struct sk_buff *skb)
newpn->pn_sk.resource = pn->pn_sk.resource;
skb_queue_head_init(&newpn->ctrlreq_queue);
newpn->pipe_handle = pipe_handle;
atomic_set(&newpn->tx_credits, 0);
newpn->peer_type = peer_type;
newpn->rx_credits = newpn->tx_credits = 0;
newpn->rx_credits = 0;
newpn->rx_fc = newpn->tx_fc = PN_LEGACY_FLOW_CONTROL;
newpn->init_enable = enabled;

Expand Down Expand Up @@ -821,14 +820,18 @@ static int pipe_skb_send(struct sock *sk, struct sk_buff *skb)
struct pep_sock *pn = pep_sk(sk);
struct pnpipehdr *ph;

if (pn_flow_safe(pn->tx_fc) &&
!atomic_add_unless(&pn->tx_credits, -1, 0)) {
kfree_skb(skb);
return -ENOBUFS;
}

skb_push(skb, 3);
skb_reset_transport_header(skb);
ph = pnp_hdr(skb);
ph->utid = 0;
ph->message_id = PNS_PIPE_DATA;
ph->pipe_handle = pn->pipe_handle;
if (pn_flow_safe(pn->tx_fc) && pn->tx_credits)
pn->tx_credits--;

return pn_skb_send(sk, skb, &pipe_srv);
}
Expand Down Expand Up @@ -866,7 +869,7 @@ static int pep_sendmsg(struct kiocb *iocb, struct sock *sk,
BUG_ON(sk->sk_state != TCP_ESTABLISHED);

/* Wait until flow control allows TX */
done = pn->tx_credits > 0;
done = atomic_read(&pn->tx_credits);
while (!done) {
DEFINE_WAIT(wait);

Expand All @@ -881,7 +884,7 @@ static int pep_sendmsg(struct kiocb *iocb, struct sock *sk,

prepare_to_wait(&sk->sk_socket->wait, &wait,
TASK_INTERRUPTIBLE);
done = sk_wait_event(sk, &timeo, pn->tx_credits > 0);
done = sk_wait_event(sk, &timeo, atomic_read(&pn->tx_credits));
finish_wait(&sk->sk_socket->wait, &wait);

if (sk->sk_state != TCP_ESTABLISHED)
Expand All @@ -895,7 +898,8 @@ static int pep_sendmsg(struct kiocb *iocb, struct sock *sk,
goto out;
skb_reserve(skb, MAX_PHONET_HEADER + 3);

if (sk->sk_state != TCP_ESTABLISHED || !pn->tx_credits)
if (sk->sk_state != TCP_ESTABLISHED ||
!atomic_read(&pn->tx_credits))
goto disabled; /* sock_alloc_send_skb might sleep */
}

Expand All @@ -917,7 +921,7 @@ int pep_writeable(struct sock *sk)
{
struct pep_sock *pn = pep_sk(sk);

return (sk->sk_state == TCP_ESTABLISHED) ? pn->tx_credits : 0;
return atomic_read(&pn->tx_credits);
}

int pep_write(struct sock *sk, struct sk_buff *skb)
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2 changes: 1 addition & 1 deletion net/phonet/socket.c
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Original file line number Diff line number Diff line change
Expand Up @@ -227,7 +227,7 @@ static unsigned int pn_socket_poll(struct file *file, struct socket *sock,
if (!mask && sk->sk_state == TCP_CLOSE_WAIT)
return POLLHUP;

if (sk->sk_state == TCP_ESTABLISHED && pn->tx_credits)
if (sk->sk_state == TCP_ESTABLISHED && atomic_read(&pn->tx_credits))
mask |= POLLOUT | POLLWRNORM | POLLWRBAND;

return mask;
Expand Down

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