Re: [PATCH] Convert balloon driver to xenstore

[Anthony Liguori <aliguori@us.ibm.com>]

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Rusty Russell wrote:

>On Tue, 2005-08-02 at 06:51 -0700, Dan Smith wrote:
>  
>
>Generally, you will want to do a module_init() and initialize your
>driver.  If it's in domain 0, it needs to be initialized later (the
>store isn't up yet): the standard way of doing this is a notifier chain.
>
>Something like the following:
>
>static struct notifier_block store_notify =
>{
>	.notifier_call = balloon_setup,
>};
>
>static int balloon_init()
>{
>	if (!xen_start_info.store_evtchn)
>		register_xenstore_notifier(&store_notify);
>	else
>		balloon_setup(&store_notify, 0, NULL);
>	return 0;
>}
>  
>
How does this look?

Regards,

Anthony Liguori

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

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diff -r dcdcec634c2d linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c
--- a/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c	Tue Aug  2 16:11:31 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/xenbus/xenbus_probe.c	Tue Aug  2 21:09:03 2005
@@ -35,9 +35,15 @@
 #include <linux/ctype.h>
 #include <linux/fcntl.h>
 #include <stdarg.h>
+#include <linux/notifier.h>
 #include "xenbus_comms.h"
 
 #define streq(a, b) (strcmp((a), (b)) == 0)
+
+/* Protects notifier chain */
+DECLARE_MUTEX(xenstore_control);
+
+static struct notifier_block *xenstore_chain;
 
 /* If something in array of ids matches this device, return it. */
 static const struct xenbus_device_id *
@@ -295,6 +301,26 @@
 	.callback = dev_changed,
 };
 
+int register_xenstore_notifier(struct notifier_block *nb)
+{
+	int ret;
+
+	if ((ret = down_interruptible(&xenstore_control)) != 0) 
+		return ret;
+	ret = notifier_chain_register(&xenstore_chain, nb);
+	up(&xenstore_control);
+	return ret;
+}
+EXPORT_SYMBOL(register_xenstore_notifier);
+
+void unregister_xenstore_notifier(struct notifier_block *nb)
+{
+	down(&xenstore_control);
+	notifier_chain_unregister(&xenstore_chain, nb);
+	up(&xenstore_control);
+}
+EXPORT_SYMBOL(unregister_xenstore_notifier);
+
 /* called from a thread in privcmd/privcmd.c */
 int do_xenbus_probe(void *unused)
 {
@@ -309,6 +335,15 @@
 		return err;
 	}
 
+	err = notifier_call_chain(&xenstore_chain, 0, 0);
+	if (err == NOTIFY_BAD) {
+		printk("%s: calling xenstore notify chain failed\n",
+		       __FUNCTION__);
+		return -EINVAL;
+	}
+
+	err = 0;
+
 	/* Initialize non-xenbus drivers */
 	balloon_init_watcher();
 
diff -r dcdcec634c2d linux-2.6-xen-sparse/include/asm-xen/xenbus.h
--- a/linux-2.6-xen-sparse/include/asm-xen/xenbus.h	Tue Aug  2 16:11:31 2005
+++ b/linux-2.6-xen-sparse/include/asm-xen/xenbus.h	Tue Aug  2 21:09:03 2005
@@ -29,6 +29,7 @@
  * IN THE SOFTWARE.
  */
 #include <linux/device.h>
+#include <linux/notifier.h>
 #include <asm/semaphore.h>
 
 /* A xenbus device. */
@@ -112,6 +113,10 @@
 	void (*callback)(struct xenbus_watch *, const char *node);
 };
 
+/* notifer routines for when the xenstore comes up */
+int register_xenstore_notifier(struct notifier_block *nb);
+void unregister_xenstore_notifier(struct notifier_block *nb);
+
 int register_xenbus_watch(struct xenbus_watch *watch);
 void unregister_xenbus_watch(struct xenbus_watch *watch);
 

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