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xen/pvcalls: implement release command 

Send PVCALLS_RELEASE to the backend and wait for a reply. Take both
in_mutex and out_mutex to avoid concurrent accesses. Then, free the
socket.

For passive sockets, check whether we have already pre-allocated an
active socket for the purpose of being accepted. If so, free that as
well.

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 15:41:02 -07:00 committed by Boris Ostrovsky
parent 5842c83596
commit 235a71c539
2 changed files with 99 additions and 0 deletions
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98
drivers/xen/pvcalls-front.c
View File

@ -199,6 +199,21 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
static void pvcalls_front_free_map(struct pvcalls_bedata *bedata,
struct sock_mapping *map)
{
int i;
unbind_from_irqhandler(map->active.irq, map);
spin_lock(&bedata->socket_lock);
if (!list_empty(&map->list))
list_del_init(&map->list);
spin_unlock(&bedata->socket_lock);
for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++)
gnttab_end_foreign_access(map->active.ring->ref[i], 0, 0);
gnttab_end_foreign_access(map->active.ref, 0, 0);
free_page((unsigned long)map->active.ring);
kfree(map);
}
static irqreturn_t pvcalls_front_conn_handler(int irq, void *sock_map)
@ -972,6 +987,89 @@ unsigned int pvcalls_front_poll(struct file *file, struct socket *sock,
return ret;
}
int pvcalls_front_release(struct socket *sock)
{
struct pvcalls_bedata *bedata;
struct sock_mapping *map;
int req_id, notify, ret;
struct xen_pvcalls_request *req;
if (sock->sk == NULL)
return 0;
pvcalls_enter();
if (!pvcalls_front_dev) {
pvcalls_exit();
return -EIO;
}
bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
map = (struct sock_mapping *) sock->sk->sk_send_head;
if (map == NULL) {
pvcalls_exit();
return 0;
}
spin_lock(&bedata->socket_lock);
ret = get_request(bedata, &req_id);
if (ret < 0) {
spin_unlock(&bedata->socket_lock);
pvcalls_exit();
return ret;
}
sock->sk->sk_send_head = NULL;
req = RING_GET_REQUEST(&bedata->ring, req_id);
req->req_id = req_id;
req->cmd = PVCALLS_RELEASE;
req->u.release.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);
wait_event(bedata->inflight_req,
READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
if (map->active_socket) {
/*
* Set in_error and wake up inflight_conn_req to force
* recvmsg waiters to exit.
*/
map->active.ring->in_error = -EBADF;
wake_up_interruptible(&map->active.inflight_conn_req);
/*
* Wait until there are no more waiters on the mutexes.
* We know that no new waiters can be added because sk_send_head
* is set to NULL -- we only need to wait for the existing
* waiters to return.
*/
while (!mutex_trylock(&map->active.in_mutex) ||
!mutex_trylock(&map->active.out_mutex))
cpu_relax();
pvcalls_front_free_map(bedata, map);
} else {
spin_lock(&bedata->socket_lock);
list_del(&map->list);
spin_unlock(&bedata->socket_lock);
if (READ_ONCE(map->passive.inflight_req_id) !=
PVCALLS_INVALID_ID) {
pvcalls_front_free_map(bedata,
map->passive.accept_map);
}
kfree(map);
}
WRITE_ONCE(bedata->rsp[req_id].req_id, PVCALLS_INVALID_ID);
pvcalls_exit();
return 0;
}
static const struct xenbus_device_id pvcalls_front_ids[] = {
{ "pvcalls" },
{ "" }

1
drivers/xen/pvcalls-front.h
View File

@ -23,5 +23,6 @@ int pvcalls_front_recvmsg(struct socket *sock,
unsigned int pvcalls_front_poll(struct file *file,
struct socket *sock,
poll_table *wait);
int pvcalls_front_release(struct socket *sock);
#endif