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[Qemu-devel] [PATCH v6 01/12] notify: add NotiferWithReturn so notifier
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v6 01/12] notify: add NotiferWithReturn so notifier list can abort |
Date: |
Mon, 24 Jun 2013 17:13:09 +0200 |
notifier_list_notify() has no return value. This is fine when we just
want to invoke side-effects.
Sometimes it's useful for notifiers to produce a return value. This
allows notifiers to "veto" an operation and will be used by the block
layer before-write notifier.
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: Kevin Wolf <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
include/qemu/notify.h | 29 +++++++++++++++++++++++++++++
util/notify.c | 30 ++++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)
diff --git a/include/qemu/notify.h b/include/qemu/notify.h
index 4e2e7f0..a3d73e4 100644
--- a/include/qemu/notify.h
+++ b/include/qemu/notify.h
@@ -40,4 +40,33 @@ void notifier_remove(Notifier *notifier);
void notifier_list_notify(NotifierList *list, void *data);
+/* Same as Notifier but allows .notify() to return errors */
+typedef struct NotifierWithReturn NotifierWithReturn;
+
+struct NotifierWithReturn {
+ /**
+ * Return 0 on success (next notifier will be invoked), otherwise
+ * notifier_with_return_list_notify() will stop and return the value.
+ */
+ int (*notify)(NotifierWithReturn *notifier, void *data);
+ QLIST_ENTRY(NotifierWithReturn) node;
+};
+
+typedef struct NotifierWithReturnList {
+ QLIST_HEAD(, NotifierWithReturn) notifiers;
+} NotifierWithReturnList;
+
+#define NOTIFIER_WITH_RETURN_LIST_INITIALIZER(head) \
+ { QLIST_HEAD_INITIALIZER((head).notifiers) }
+
+void notifier_with_return_list_init(NotifierWithReturnList *list);
+
+void notifier_with_return_list_add(NotifierWithReturnList *list,
+ NotifierWithReturn *notifier);
+
+void notifier_with_return_remove(NotifierWithReturn *notifier);
+
+int notifier_with_return_list_notify(NotifierWithReturnList *list,
+ void *data);
+
#endif
diff --git a/util/notify.c b/util/notify.c
index 7b7692a..f215dfc 100644
--- a/util/notify.c
+++ b/util/notify.c
@@ -39,3 +39,33 @@ void notifier_list_notify(NotifierList *list, void *data)
notifier->notify(notifier, data);
}
}
+
+void notifier_with_return_list_init(NotifierWithReturnList *list)
+{
+ QLIST_INIT(&list->notifiers);
+}
+
+void notifier_with_return_list_add(NotifierWithReturnList *list,
+ NotifierWithReturn *notifier)
+{
+ QLIST_INSERT_HEAD(&list->notifiers, notifier, node);
+}
+
+void notifier_with_return_remove(NotifierWithReturn *notifier)
+{
+ QLIST_REMOVE(notifier, node);
+}
+
+int notifier_with_return_list_notify(NotifierWithReturnList *list, void *data)
+{
+ NotifierWithReturn *notifier, *next;
+ int ret = 0;
+
+ QLIST_FOREACH_SAFE(notifier, &list->notifiers, node, next) {
+ ret = notifier->notify(notifier, data);
+ if (ret != 0) {
+ break;
+ }
+ }
+ return ret;
+}
--
1.8.1.4
- [Qemu-devel] [PATCH v6 00/12] block: drive-backup live backup command, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 01/12] notify: add NotiferWithReturn so notifier list can abort,
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v6 09/12] blockdev: add DriveBackup transaction, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 08/12] blockdev: allow BdrvActionOps->commit() to be NULL, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 03/12] block: add basic backup support to block driver, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 10/12] blockdev: add Abort transaction, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 11/12] qemu-iotests: extract wait_until_completed() into iotests.py, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 05/12] blockdev: use bdrv_getlength() in qmp_drive_mirror(), Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 02/12] block: add bdrv_add_before_write_notifier(), Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 04/12] blockdev: drop redundant proto_drv check, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 06/12] block: add drive-backup QMP command, Stefan Hajnoczi, 2013/06/24