[PATCH v4 03/18] xen/pvcalls: initialize the module and register the xenbus backend

From: Stefano Stabellini
Date: Thu Jun 15 2017 - 15:13:04 EST


Keep a list of connected frontends. Use a semaphore to protect list
accesses.

Signed-off-by: Stefano Stabellini <stefano@xxxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
CC: boris.ostrovsky@xxxxxxxxxx
CC: jgross@xxxxxxxx
---
drivers/xen/pvcalls-back.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index f3d0daa..9044cf2 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -25,6 +25,11 @@
#include <xen/xenbus.h>
#include <xen/interface/io/pvcalls.h>

+struct pvcalls_back_global {
+ struct list_head frontends;
+ struct semaphore frontends_lock;
+} pvcalls_back_global;
+
static int pvcalls_back_probe(struct xenbus_device *dev,
const struct xenbus_device_id *id)
{
@@ -59,3 +64,20 @@ static int pvcalls_back_uevent(struct xenbus_device *xdev,
.uevent = pvcalls_back_uevent,
.otherend_changed = pvcalls_back_changed,
};
+
+static int __init pvcalls_back_init(void)
+{
+ int ret;
+
+ if (!xen_domain())
+ return -ENODEV;
+
+ ret = xenbus_register_backend(&pvcalls_back_driver);
+ if (ret < 0)
+ return ret;
+
+ sema_init(&pvcalls_back_global.frontends_lock, 1);
+ INIT_LIST_HEAD(&pvcalls_back_global.frontends);
+ return 0;
+}
+module_init(pvcalls_back_init);
--
1.9.1