linux-kernel - [PATCH v3 02/13] xen/pvcalls: implement frontend disconnect

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Date:   Mon, 31 Jul 2017 15:57:24 -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 v3 02/13] xen/pvcalls: implement frontend disconnect

Introduce a data structure named pvcalls_bedata. It contains pointers to
the command ring, the event channel, a list of active sockets and a list
of passive sockets. Lists accesses are protected by a spin_lock.

Introduce a waitqueue to allow waiting for a response on commands sent
to the backend.

Introduce an array of struct xen_pvcalls_response to store commands
responses.

Implement pvcalls frontend removal function. Go through the list of
active and passive sockets and free them all, one at a time.

Signed-off-by: Stefano Stabellini <stefano@...reto.com>
CC: boris.ostrovsky@...cle.com
CC: jgross@...e.com
---
 drivers/xen/pvcalls-front.c | 51 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index a8d38c2..a126195 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -20,6 +20,29 @@
 #include <xen/xenbus.h>
 #include <xen/interface/io/pvcalls.h>
 
+#define PVCALLS_INVALID_ID UINT_MAX
+#define PVCALLS_RING_ORDER XENBUS_MAX_RING_GRANT_ORDER
+#define PVCALLS_NR_REQ_PER_RING __CONST_RING_SIZE(xen_pvcalls, XEN_PAGE_SIZE)
+
+struct pvcalls_bedata {
+	struct xen_pvcalls_front_ring ring;
+	grant_ref_t ref;
+	int irq;
+
+	struct list_head socket_mappings;
+	struct list_head socketpass_mappings;
+	spinlock_t pvcallss_lock;
+
+	wait_queue_head_t inflight_req;
+	struct xen_pvcalls_response rsp[PVCALLS_NR_REQ_PER_RING];
+};
+static struct xenbus_device *pvcalls_front_dev;
+
+static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
+{
+	return IRQ_HANDLED;
+}
+
 static const struct xenbus_device_id pvcalls_front_ids[] = {
 	{ "pvcalls" },
 	{ "" }
@@ -27,6 +50,34 @@
 
 static int pvcalls_front_remove(struct xenbus_device *dev)
 {
+	struct pvcalls_bedata *bedata;
+	struct sock_mapping *map = NULL, *n;
+
+	bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
+
+	list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
+		mutex_lock(&map->active.in_mutex);
+		mutex_lock(&map->active.out_mutex);
+		pvcalls_front_free_map(bedata, map);
+		mutex_unlock(&map->active.out_mutex);
+		mutex_unlock(&map->active.in_mutex);
+		kfree(map);
+	}
+	list_for_each_entry_safe(map, n, &bedata->socketpass_mappings, list) {
+		spin_lock(&bedata->pvcallss_lock);
+		list_del_init(&map->list);
+		spin_unlock(&bedata->pvcallss_lock);
+		kfree(map);
+	}
+	if (bedata->irq > 0)
+		unbind_from_irqhandler(bedata->irq, dev);
+	if (bedata->ref >= 0)
+		gnttab_end_foreign_access(bedata->ref, 0, 0);
+	kfree(bedata->ring.sring);
+	kfree(bedata);
+	dev_set_drvdata(&dev->dev, NULL);
+	xenbus_switch_state(dev, XenbusStateClosed);
+	pvcalls_front_dev = NULL;
 	return 0;
 }
 
-- 
1.9.1