xen: fixes for 5.2-rc3

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Merge tag 'for-linus-5.2b-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fixes from Juergen Gross:
 "One minor cleanup patch and a fix for handling of live migration when
  running as Xen guest"

* tag 'for-linus-5.2b-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xenbus: Avoid deadlock during suspend due to open transactions
  xen/pvcalls: Remove set but not used variable

drivers/xen/pvcalls-front.c

@@ -531,7 +531,6 @@ out:
 int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg,
 			  size_t len)
 {
-	struct pvcalls_bedata *bedata;
 	struct sock_mapping *map;
 	int sent, tot_sent = 0;
 	int count = 0, flags;
@@ -543,7 +542,6 @@ int pvcalls_front_sendmsg(struct socket *sock, struct msghdr *msg,
 	map = pvcalls_enter_sock(sock);
 	if (IS_ERR(map))
 		return PTR_ERR(map);
-	bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
 
 	mutex_lock(&map->active.out_mutex);
 	if ((flags & MSG_DONTWAIT) && !pvcalls_front_write_todo(map)) {
@@ -626,7 +624,6 @@ out:
 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;
 
@@ -636,7 +633,6 @@ int pvcalls_front_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 	map = pvcalls_enter_sock(sock);
 	if (IS_ERR(map))
 		return PTR_ERR(map);
-	bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
 
 	mutex_lock(&map->active.in_mutex);
 	if (len > XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER))

drivers/xen/xenbus/xenbus.h

@@ -83,6 +83,7 @@ struct xb_req_data {
 	int num_vecs;
 	int err;
 	enum xb_req_state state;
+	bool user_req;
 	void (*cb)(struct xb_req_data *);
 	void *par;
 };
@@ -133,4 +134,6 @@ void xenbus_ring_ops_init(void);
 int xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void *par);
 void xenbus_dev_queue_reply(struct xb_req_data *req);
 
+extern unsigned int xb_dev_generation_id;
+
 #endif

drivers/xen/xenbus/xenbus_dev_frontend.c

@@ -62,6 +62,8 @@
 
 #include "xenbus.h"
 
+unsigned int xb_dev_generation_id;
+
 /*
  * An element of a list of outstanding transactions, for which we're
  * still waiting a reply.
@@ -69,6 +71,7 @@
 struct xenbus_transaction_holder {
 	struct list_head list;
 	struct xenbus_transaction handle;
+	unsigned int generation_id;
 };
 
 /*
@@ -441,6 +444,7 @@ static int xenbus_write_transaction(unsigned msg_type,
 			rc = -ENOMEM;
 			goto out;
 		}
+		trans->generation_id = xb_dev_generation_id;
 		list_add(&trans->list, &u->transactions);
 	} else if (msg->hdr.tx_id != 0 &&
 		   !xenbus_get_transaction(u, msg->hdr.tx_id))
@@ -449,6 +453,20 @@ static int xenbus_write_transaction(unsigned msg_type,
 		 !(msg->hdr.len == 2 &&
 		   (!strcmp(msg->body, "T") || !strcmp(msg->body, "F"))))
 		return xenbus_command_reply(u, XS_ERROR, "EINVAL");
+	else if (msg_type == XS_TRANSACTION_END) {
+		trans = xenbus_get_transaction(u, msg->hdr.tx_id);
+		if (trans && trans->generation_id != xb_dev_generation_id) {
+			list_del(&trans->list);
+			kfree(trans);
+			if (!strcmp(msg->body, "T"))
+				return xenbus_command_reply(u, XS_ERROR,
+							    "EAGAIN");
+			else
+				return xenbus_command_reply(u,
+							    XS_TRANSACTION_END,
+							    "OK");
+		}
+	}
 
 	rc = xenbus_dev_request_and_reply(&msg->hdr, u);
 	if (rc && trans) {

drivers/xen/xenbus/xenbus_xs.c

@@ -105,6 +105,7 @@ static void xs_suspend_enter(void)
 
 static void xs_suspend_exit(void)
 {
+	xb_dev_generation_id++;
 	spin_lock(&xs_state_lock);
 	xs_suspend_active--;
 	spin_unlock(&xs_state_lock);
@@ -125,7 +126,7 @@ static uint32_t xs_request_enter(struct xb_req_data *req)
 		spin_lock(&xs_state_lock);
 	}
 
-	if (req->type == XS_TRANSACTION_START)
+	if (req->type == XS_TRANSACTION_START && !req->user_req)
 		xs_state_users++;
 	xs_state_users++;
 	rq_id = xs_request_id++;
@@ -140,7 +141,7 @@ void xs_request_exit(struct xb_req_data *req)
 	spin_lock(&xs_state_lock);
 	xs_state_users--;
 	if ((req->type == XS_TRANSACTION_START && req->msg.type == XS_ERROR) ||
-	    (req->type == XS_TRANSACTION_END &&
+	    (req->type == XS_TRANSACTION_END && !req->user_req &&
 	     !WARN_ON_ONCE(req->msg.type == XS_ERROR &&
 			   !strcmp(req->body, "ENOENT"))))
 		xs_state_users--;
@@ -286,6 +287,7 @@ int xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void *par)
 	req->num_vecs = 1;
 	req->cb = xenbus_dev_queue_reply;
 	req->par = par;
+	req->user_req = true;
 
 	xs_send(req, msg);
 
@@ -313,6 +315,7 @@ static void *xs_talkv(struct xenbus_transaction t,
 	req->vec = iovec;
 	req->num_vecs = num_vecs;
 	req->cb = xs_wake_up;
+	req->user_req = false;
 
 	msg.req_id = 0;
 	msg.tx_id = t.id;