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af_iucv: Return -EAGAIN if iucv msg limit is exceeded 

If the iucv message limit for a communication path is exceeded,
sendmsg() returns -EAGAIN instead of -EPIPE.
The calling application can then handle this error situtation,
e.g. to try again after waiting some time.

For blocking sockets, sendmsg() waits up to the socket timeout
before returning -EAGAIN. For the new wait condition, a macro
has been introduced and the iucv_sock_wait_state() has been
refactored to this macro.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hendrik Brueckner 2009-06-17 21:54:48 +00:00 committed by David S. Miller
parent bb664f49f8
commit 0ea920d211
2 changed files with 103 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/iucv/af_iucv.h
View File

@ -94,8 +94,6 @@ unsigned int iucv_sock_poll(struct file *file, struct socket *sock,
poll_table *wait);
void iucv_sock_link(struct iucv_sock_list *l, struct sock *s);
void iucv_sock_unlink(struct iucv_sock_list *l, struct sock *s);
int iucv_sock_wait_state(struct sock *sk, int state, int state2,
unsigned long timeo);
int iucv_sock_wait_cnt(struct sock *sk, unsigned long timeo);
void iucv_accept_enqueue(struct sock *parent, struct sock *sk);
void iucv_accept_unlink(struct sock *sk);

144
net/iucv/af_iucv.c
View File

@ -53,6 +53,38 @@ static const u8 iprm_shutdown[8] =
#define CB_TRGCLS(skb) ((skb)->cb + CB_TAG_LEN) /* iucv msg target class */
#define CB_TRGCLS_LEN (TRGCLS_SIZE)
#define __iucv_sock_wait(sk, condition, timeo, ret) \
do { \
DEFINE_WAIT(__wait); \
long __timeo = timeo; \
ret = 0; \
while (!(condition)) { \
prepare_to_wait(sk->sk_sleep, &__wait, TASK_INTERRUPTIBLE); \
if (!__timeo) { \
ret = -EAGAIN; \
break; \
} \
if (signal_pending(current)) { \
ret = sock_intr_errno(__timeo); \
break; \
} \
release_sock(sk); \
__timeo = schedule_timeout(__timeo); \
lock_sock(sk); \
ret = sock_error(sk); \
if (ret) \
break; \
} \
finish_wait(sk->sk_sleep, &__wait); \
} while (0)
#define iucv_sock_wait(sk, condition, timeo) \
({ \
int __ret = 0; \
if (!(condition)) \
__iucv_sock_wait(sk, condition, timeo, __ret); \
__ret; \
})
static void iucv_sock_kill(struct sock *sk);
static void iucv_sock_close(struct sock *sk);
@ -121,6 +153,48 @@ static inline size_t iucv_msg_length(struct iucv_message *msg)
return msg->length;
}
/**
* iucv_sock_in_state() - check for specific states
* @sk: sock structure
* @state: first iucv sk state
* @state: second iucv sk state
*
* Returns true if the socket in either in the first or second state.
*/
static int iucv_sock_in_state(struct sock *sk, int state, int state2)
{
return (sk->sk_state == state || sk->sk_state == state2);
}
/**
* iucv_below_msglim() - function to check if messages can be sent
* @sk: sock structure
*
* Returns true if the send queue length is lower than the message limit.
* Always returns true if the socket is not connected (no iucv path for
* checking the message limit).
*/
static inline int iucv_below_msglim(struct sock *sk)
{
struct iucv_sock *iucv = iucv_sk(sk);
if (sk->sk_state != IUCV_CONNECTED)
return 1;
return (skb_queue_len(&iucv->send_skb_q) < iucv->path->msglim);
}
/**
* iucv_sock_wake_msglim() - Wake up thread waiting on msg limit
*/
static void iucv_sock_wake_msglim(struct sock *sk)
{
read_lock(&sk->sk_callback_lock);
if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
wake_up_interruptible_all(sk->sk_sleep);
sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
read_unlock(&sk->sk_callback_lock);
}
/* Timers */
static void iucv_sock_timeout(unsigned long arg)
{
@ -212,7 +286,9 @@ static void iucv_sock_close(struct sock *sk)
timeo = sk->sk_lingertime;
else
timeo = IUCV_DISCONN_TIMEOUT;
err = iucv_sock_wait_state(sk, IUCV_CLOSED, 0, timeo);
err = iucv_sock_wait(sk,
iucv_sock_in_state(sk, IUCV_CLOSED, 0),
timeo);
}
case IUCV_CLOSING: /* fall through */
@ -393,39 +469,6 @@ struct sock *iucv_accept_dequeue(struct sock *parent, struct socket *newsock)
return NULL;
}
int iucv_sock_wait_state(struct sock *sk, int state, int state2,
unsigned long timeo)
{
DECLARE_WAITQUEUE(wait, current);
int err = 0;
add_wait_queue(sk->sk_sleep, &wait);
while (sk->sk_state != state && sk->sk_state != state2) {
set_current_state(TASK_INTERRUPTIBLE);
if (!timeo) {
err = -EAGAIN;
break;
}
if (signal_pending(current)) {
err = sock_intr_errno(timeo);
break;
}
release_sock(sk);
timeo = schedule_timeout(timeo);
lock_sock(sk);
err = sock_error(sk);
if (err)
break;
}
set_current_state(TASK_RUNNING);
remove_wait_queue(sk->sk_sleep, &wait);
return err;
}
/* Bind an unbound socket */
static int iucv_sock_bind(struct socket *sock, struct sockaddr *addr,
int addr_len)
@ -570,8 +613,9 @@ static int iucv_sock_connect(struct socket *sock, struct sockaddr *addr,
}
if (sk->sk_state != IUCV_CONNECTED) {
err = iucv_sock_wait_state(sk, IUCV_CONNECTED, IUCV_DISCONN,
sock_sndtimeo(sk, flags & O_NONBLOCK));
err = iucv_sock_wait(sk, iucv_sock_in_state(sk, IUCV_CONNECTED,
IUCV_DISCONN),
sock_sndtimeo(sk, flags & O_NONBLOCK));
}
if (sk->sk_state == IUCV_DISCONN) {
@ -725,9 +769,11 @@ static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
struct iucv_message txmsg;
struct cmsghdr *cmsg;
int cmsg_done;
long timeo;
char user_id[9];
char appl_id[9];
int err;
int noblock = msg->msg_flags & MSG_DONTWAIT;
err = sock_error(sk);
if (err)
@ -799,8 +845,7 @@ static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
* this is fine for SOCK_SEQPACKET (unless we want to support
* segmented records using the MSG_EOR flag), but
* for SOCK_STREAM we might want to improve it in future */
skb = sock_alloc_send_skb(sk, len, msg->msg_flags & MSG_DONTWAIT,
&err);
skb = sock_alloc_send_skb(sk, len, noblock, &err);
if (!skb)
goto out;
if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
@ -808,6 +853,18 @@ static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
goto fail;
}
/* wait if outstanding messages for iucv path has reached */
timeo = sock_sndtimeo(sk, noblock);
err = iucv_sock_wait(sk, iucv_below_msglim(sk), timeo);
if (err)
goto fail;
/* return -ECONNRESET if the socket is no longer connected */
if (sk->sk_state != IUCV_CONNECTED) {
err = -ECONNRESET;
goto fail;
}
/* increment and save iucv message tag for msg_completion cbk */
txmsg.tag = iucv->send_tag++;
memcpy(CB_TAG(skb), &txmsg.tag, CB_TAG_LEN);
@ -844,9 +901,10 @@ static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
pr_err("Application %s on z/VM guest %s"
" exceeds message limit\n",
appl_id, user_id);
}
err = -EAGAIN;
} else
err = -EPIPE;
skb_unlink(skb, &iucv->send_skb_q);
err = -EPIPE;
goto fail;
}
@ -1463,7 +1521,11 @@ static void iucv_callback_txdone(struct iucv_path *path,
spin_unlock_irqrestore(&list->lock, flags);
kfree_skb(this);
if (this) {
kfree_skb(this);
/* wake up any process waiting for sending */
iucv_sock_wake_msglim(sk);
}
}
BUG_ON(!this);