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xen/pvcalls: implement recvmsg

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Implement recvmsg by copying data from the "in" ring. If not enough data
is available and the recvmsg call is blocking, then wait on the
inflight_conn_req waitqueue. Take the active socket in_mutex so that
only one function can access the ring at any given time.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
This commit is contained in:
Stefano Stabellini 2017-10-30 15:41:00 -07:00 committed by Boris Ostrovsky
parent 45ddce214a
commit ae0d04052e
2 changed files with 115 additions and 0 deletions
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111
drivers/xen/pvcalls-front.c
View file

@ -117,6 +117,20 @@ static bool pvcalls_front_write_todo(struct sock_mapping *map)
return !!(size - pvcalls_queued(prod, cons, size));
}
static bool pvcalls_front_read_todo(struct sock_mapping *map)
{
struct pvcalls_data_intf *intf = map->active.ring;
RING_IDX cons, prod;
int32_t error;
cons = intf->in_cons;
prod = intf->in_prod;
error = intf->in_error;
return (error != 0 ||
pvcalls_queued(prod, cons,
XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER)) != 0);
}
static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
{
struct xenbus_device *dev = dev_id;
@ -484,6 +498,103 @@ int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg,
return tot_sent;
}
static int __read_ring(struct pvcalls_data_intf *intf,
struct pvcalls_data *data,
struct iov_iter *msg_iter,
size_t len, int flags)
{
RING_IDX cons, prod, size, masked_prod, masked_cons;
RING_IDX array_size = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
int32_t error;
cons = intf->in_cons;
prod = intf->in_prod;
error = intf->in_error;
/* get pointers before reading from the ring */
virt_rmb();
if (error < 0)
return error;
size = pvcalls_queued(prod, cons, array_size);
masked_prod = pvcalls_mask(prod, array_size);
masked_cons = pvcalls_mask(cons, array_size);
if (size == 0)
return 0;
if (len > size)
len = size;
if (masked_prod > masked_cons) {
len = copy_to_iter(data->in + masked_cons, len, msg_iter);
} else {
if (len > (array_size - masked_cons)) {
int ret = copy_to_iter(data->in + masked_cons,
array_size - masked_cons, msg_iter);
if (ret != array_size - masked_cons) {
len = ret;
goto out;
}
len = ret + copy_to_iter(data->in, len - ret, msg_iter);
} else {
len = copy_to_iter(data->in + masked_cons, len, msg_iter);
}
}
out:
/* read data from the ring before increasing the index */
virt_mb();
if (!(flags & MSG_PEEK))
intf->in_cons += len;
return len;
}
int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
int flags)
{
struct pvcalls_bedata *bedata;
int ret;
struct sock_mapping *map;
if (flags & (MSG_CMSG_CLOEXEC|MSG_ERRQUEUE|MSG_OOB|MSG_TRUNC))
return -EOPNOTSUPP;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -ENOTCONN;
}
bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
map = (struct sock_mapping *) sock->sk->sk_send_head;
if (!map) {
pvcalls_exit();
return -ENOTSOCK;
}
mutex_lock(&map->active.in_mutex);
if (len > XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER))
len = XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER);
while (!(flags & MSG_DONTWAIT) && !pvcalls_front_read_todo(map)) {
wait_event_interruptible(map->active.inflight_conn_req,
pvcalls_front_read_todo(map));
}
ret = __read_ring(map->active.ring, &map->active.data,
&msg->msg_iter, len, flags);
if (ret > 0)
notify_remote_via_irq(map->active.irq);
if (ret == 0)
ret = (flags & MSG_DONTWAIT) ? -EAGAIN : 0;
if (ret == -ENOTCONN)
ret = 0;
mutex_unlock(&map->active.in_mutex);
pvcalls_exit();
return ret;
}
int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
{
struct pvcalls_bedata *bedata;

4
drivers/xen/pvcalls-front.h
View file

@ -16,5 +16,9 @@ int pvcalls_front_accept(struct socket *sock,
int pvcalls_front_sendmsg(struct socket *sock,
struct msghdr *msg,
size_t len);
int pvcalls_front_recvmsg(struct socket *sock,
struct msghdr *msg,
size_t len,
int flags);
#endif