linux-kernel - [PATCH v2 13/18] xen/pvcalls: implement release command

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Date:   Fri, 19 May 2017 16:22:54 -0700
From:   Stefano Stabellini <sstabellini@...nel.org>
To:     xen-devel@...ts.xen.org
Cc:     linux-kernel@...r.kernel.org, sstabellini@...nel.org,
        jgross@...e.com, boris.ostrovsky@...cle.com,
        Stefano Stabellini <stefano@...reto.com>
Subject: [PATCH v2 13/18] xen/pvcalls: implement release command

Release both active and passive sockets. For active sockets, make sure
to avoid possible conflicts with the ioworker reading/writing to those
sockets concurrently. Set map->release to let the ioworker know
atomically that the socket will be released soon, then wait until the
ioworker finishes (flush_work).

Unmap indexes pages and data rings.

Signed-off-by: Stefano Stabellini <stefano@...reto.com>
CC: boris.ostrovsky@...cle.com
CC: jgross@...e.com
---
 drivers/xen/pvcalls-back.c | 72 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 71 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 5ff1504..363a550 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -257,13 +257,83 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
 				       struct pvcalls_back_priv *priv,
 				       struct sock_mapping *map)
 {
+	disable_irq(map->irq);
+	if (map->sock->sk != NULL) {
+		write_lock_bh(&map->sock->sk->sk_callback_lock);
+		map->sock->sk->sk_user_data = NULL;
+		map->sock->sk->sk_data_ready = map->saved_data_ready;
+		write_unlock_bh(&map->sock->sk->sk_callback_lock);
+	}
+
+	atomic_set(&map->release, 1);
+	flush_work(&map->ioworker.register_work);
+
+	down(&priv->socket_lock);
+	list_del(&map->list);
+	up(&priv->socket_lock);
+
+	xenbus_unmap_ring_vfree(dev, (void *)map->bytes);
+	xenbus_unmap_ring_vfree(dev, (void *)map->ring);
+	unbind_from_irqhandler(map->irq, map);
+
+	sock_release(map->sock);
+	kfree(map);
+
+	return 0;
+}
+
+static int pvcalls_back_release_passive(struct xenbus_device *dev,
+					struct pvcalls_back_priv *priv,
+					struct sockpass_mapping *mappass)
+{
+	if (mappass->sock->sk != NULL) {
+		write_lock_bh(&mappass->sock->sk->sk_callback_lock);
+		mappass->sock->sk->sk_user_data = NULL;
+		mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
+		write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
+	}
+	down(&priv->socket_lock);
+	radix_tree_delete(&priv->socketpass_mappings, mappass->id);
+	sock_release(mappass->sock);
+	flush_workqueue(mappass->wq);
+	destroy_workqueue(mappass->wq);
+	kfree(mappass);
+	up(&priv->socket_lock);
+
 	return 0;
 }
 
 static int pvcalls_back_release(struct xenbus_device *dev,
 				struct xen_pvcalls_request *req)
 {
-	return 0;
+	struct pvcalls_back_priv *priv;
+	struct sock_mapping *map, *n;
+	struct sockpass_mapping *mappass;
+	int ret = 0;
+	struct xen_pvcalls_response *rsp;
+
+	priv = dev_get_drvdata(&dev->dev);
+
+	list_for_each_entry_safe(map, n, &priv->socket_mappings, list) {
+		if (map->id == req->u.release.id) {
+			ret = pvcalls_back_release_active(dev, priv, map);
+			goto out;
+		}
+	}
+	mappass = radix_tree_lookup(&priv->socketpass_mappings,
+				    req->u.release.id);
+	if (mappass != NULL) {
+		ret = pvcalls_back_release_passive(dev, priv, mappass);
+		goto out;
+	}
+
+out:
+	rsp = RING_GET_RESPONSE(&priv->ring, priv->ring.rsp_prod_pvt++);
+	rsp->req_id = req->req_id;
+	rsp->u.release.id = req->u.release.id;
+	rsp->cmd = req->cmd;
+	rsp->ret = ret;
+	return ret;
 }
 
 static void __pvcalls_back_accept(struct work_struct *work)
-- 
1.9.1