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xen/pvcalls: implement poll command

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For active sockets, check the indexes and use the inflight_conn_req
waitqueue to wait.

For passive sockets if an accept is outstanding
(PVCALLS_FLAG_ACCEPT_INFLIGHT), check if it has been answered by looking
at bedata->rsp[req_id]. If so, return POLLIN.  Otherwise use the
inflight_accept_req waitqueue.

If no accepts are inflight, send PVCALLS_POLL to the backend. If we have
outstanding POLL requests awaiting for a response use the inflight_req
waitqueue: inflight_req is awaken when a new response is received; on
wakeup we check whether the POLL response is arrived by looking at the
PVCALLS_FLAG_POLL_RET flag. We set the flag from
pvcalls_front_event_handler, if the response was for a POLL command.

In pvcalls_front_event_handler, get the struct sock_mapping from the
poll id (we previously converted struct sock_mapping* to uintptr_t and
used it as id).

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 15:41:01 -07:00 committed by Boris Ostrovsky
parent ae0d04052e
commit 5842c83596
2 changed files with 138 additions and 9 deletions
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144
drivers/xen/pvcalls-front.c
View File

@ -83,6 +83,8 @@ struct sock_mapping {
* Only one poll operation can be inflight for a given socket.
*/
#define PVCALLS_FLAG_ACCEPT_INFLIGHT 0
#define PVCALLS_FLAG_POLL_INFLIGHT 1
#define PVCALLS_FLAG_POLL_RET 2
uint8_t flags;
uint32_t inflight_req_id;
struct sock_mapping *accept_map;
@ -154,15 +156,32 @@ again:
rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons);
req_id = rsp->req_id;
dst = (uint8_t *)&bedata->rsp[req_id] + sizeof(rsp->req_id);
src = (uint8_t *)rsp + sizeof(rsp->req_id);
memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id));
/*
* First copy the rest of the data, then req_id. It is
* paired with the barrier when accessing bedata->rsp.
*/
smp_wmb();
bedata->rsp[req_id].req_id = rsp->req_id;
if (rsp->cmd == PVCALLS_POLL) {
struct sock_mapping *map = (struct sock_mapping *)(uintptr_t)
rsp->u.poll.id;
clear_bit(PVCALLS_FLAG_POLL_INFLIGHT,
(void *)&map->passive.flags);
/*
* clear INFLIGHT, then set RET. It pairs with
* the checks at the beginning of
* pvcalls_front_poll_passive.
*/
smp_wmb();
set_bit(PVCALLS_FLAG_POLL_RET,
(void *)&map->passive.flags);
} else {
dst = (uint8_t *)&bedata->rsp[req_id] +
sizeof(rsp->req_id);
src = (uint8_t *)rsp + sizeof(rsp->req_id);
memcpy(dst, src, sizeof(*rsp) - sizeof(rsp->req_id));
/*
* First copy the rest of the data, then req_id. It is
* paired with the barrier when accessing bedata->rsp.
*/
smp_wmb();
bedata->rsp[req_id].req_id = req_id;
}
done = 1;
bedata->ring.rsp_cons++;
@ -846,6 +865,113 @@ received:
return ret;
}
static unsigned int pvcalls_front_poll_passive(struct file *file,
struct pvcalls_bedata *bedata,
struct sock_mapping *map,
poll_table *wait)
{
int notify, req_id, ret;
struct xen_pvcalls_request *req;
if (test_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
(void *)&map->passive.flags)) {
uint32_t req_id = READ_ONCE(map->passive.inflight_req_id);
if (req_id != PVCALLS_INVALID_ID &&
READ_ONCE(bedata->rsp[req_id].req_id) == req_id)
return POLLIN | POLLRDNORM;
poll_wait(file, &map->passive.inflight_accept_req, wait);
return 0;
}
if (test_and_clear_bit(PVCALLS_FLAG_POLL_RET,
(void *)&map->passive.flags))
return POLLIN | POLLRDNORM;
/*
* First check RET, then INFLIGHT. No barriers necessary to
* ensure execution ordering because of the conditional
* instructions creating control dependencies.
*/
if (test_and_set_bit(PVCALLS_FLAG_POLL_INFLIGHT,
(void *)&map->passive.flags)) {
poll_wait(file, &bedata->inflight_req, wait);
return 0;
}
spin_lock(&bedata->socket_lock);
ret = get_request(bedata, &req_id);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
return ret;
}
req = RING_GET_REQUEST(&bedata->ring, req_id);
req->req_id = req_id;
req->cmd = PVCALLS_POLL;
req->u.poll.id = (uintptr_t) map;
bedata->ring.req_prod_pvt++;
RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&bedata->ring, notify);
spin_unlock(&bedata->socket_lock);
if (notify)
notify_remote_via_irq(bedata->irq);
poll_wait(file, &bedata->inflight_req, wait);
return 0;
}
static unsigned int pvcalls_front_poll_active(struct file *file,
struct pvcalls_bedata *bedata,
struct sock_mapping *map,
poll_table *wait)
{
unsigned int mask = 0;
int32_t in_error, out_error;
struct pvcalls_data_intf *intf = map->active.ring;
out_error = intf->out_error;
in_error = intf->in_error;
poll_wait(file, &map->active.inflight_conn_req, wait);
if (pvcalls_front_write_todo(map))
mask |= POLLOUT | POLLWRNORM;
if (pvcalls_front_read_todo(map))
mask |= POLLIN | POLLRDNORM;
if (in_error != 0 || out_error != 0)
mask |= POLLERR;
return mask;
}
unsigned int pvcalls_front_poll(struct file *file, struct socket *sock,
poll_table *wait)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map;
int ret;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return POLLNVAL;
}
bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
map = (struct sock_mapping *) sock->sk->sk_send_head;
if (!map) {
pvcalls_exit();
return POLLNVAL;
}
if (map->active_socket)
ret = pvcalls_front_poll_active(file, bedata, map, wait);
else
ret = pvcalls_front_poll_passive(file, bedata, map, wait);
pvcalls_exit();
return ret;
}
static const struct xenbus_device_id pvcalls_front_ids[] = {
{ "pvcalls" },
{ "" }

3
drivers/xen/pvcalls-front.h
View File

@ -20,5 +20,8 @@ int pvcalls_front_recvmsg(struct socket *sock,
struct msghdr *msg,
size_t len,
int flags);
unsigned int pvcalls_front_poll(struct file *file,
struct socket *sock,
poll_table *wait);
#endif