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[Qemu-devel] [PULL 02/20] notify: add NotiferWithReturn so notifier list
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PULL 02/20] notify: add NotiferWithReturn so notifier list can abort |
Date: |
Fri, 28 Jun 2013 16:24:51 +0200 |
From: Stefan Hajnoczi <address@hidden>
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>
Signed-off-by: Kevin Wolf <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] [PULL 00/20] Block patches, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 01/20] raw-posix: Fix /dev/cdrom magic on OS X, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 02/20] notify: add NotiferWithReturn so notifier list can abort,
Kevin Wolf <=
- [Qemu-devel] [PULL 03/20] block: add bdrv_add_before_write_notifier(), Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 06/20] blockdev: use bdrv_getlength() in qmp_drive_mirror(), Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 04/20] block: add basic backup support to block driver, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 05/20] blockdev: drop redundant proto_drv check, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 09/20] blockdev: allow BdrvActionOps->commit() to be NULL, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 07/20] block: add drive-backup QMP command, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 10/20] blockdev: add DriveBackup transaction, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 08/20] blockdev: rename BlkTransactionStates to singular, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 11/20] blockdev: add Abort transaction, Kevin Wolf, 2013/06/28
- [Qemu-devel] [PULL 12/20] qemu-iotests: extract wait_until_completed() into iotests.py, Kevin Wolf, 2013/06/28