Merge remote-tracking branch 'remotes/armbru/tags/pull-yank-2021-01-13' into staging

Yank patches patches for 2021-01-13

# gpg: Signature made Wed 13 Jan 2021 09:25:46 GMT
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-yank-2021-01-13:
  tests/test-char.c: Wait for the chardev to connect in char_socket_client_dupid_test
  io: Document qmp oob suitability of qio_channel_shutdown and io_shutdown
  io/channel-tls.c: make qio_channel_tls_shutdown thread-safe
  migration: Add yank feature
  chardev/char-socket.c: Add yank feature
  block/nbd.c: Add yank feature
  Introduce yank feature

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 101 insertions, 1 deletions

diff --git a/include/io/channel.h b/include/io/channel.h
index 4d6fe45f63..ab9ea77959 100644
--- a/include/io/channel.h
+++ b/include/io/channel.h
@@ -92,7 +92,8 @@ struct QIOChannel {
  * provide additional optional features.
  *
  * Consult the corresponding public API docs for a description
- * of the semantics of each callback
+ * of the semantics of each callback. io_shutdown in particular
+ * must be thread-safe, terminate quickly and must not block.
  */
 struct QIOChannelClass {
     ObjectClass parent;
@@ -510,6 +511,8 @@ int qio_channel_close(QIOChannel *ioc,
  * QIO_CHANNEL_FEATURE_SHUTDOWN prior to calling
  * this method.
  *
+ * This function is thread-safe, terminates quickly and does not block.
+ *
  * Returns: 0 on success, -1 on error
  */
 int qio_channel_shutdown(QIOChannel *ioc,
diff --git a/include/qemu/yank.h b/include/qemu/yank.h
new file mode 100644
index 0000000000..5b93c70cbf
--- /dev/null
+++ b/include/qemu/yank.h
@@ -0,0 +1,97 @@
+/*
+ * QEMU yank feature
+ *
+ * Copyright (c) Lukas Straub <lukasstraub2@web.de>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef YANK_H
+#define YANK_H
+
+#include "qapi/qapi-types-yank.h"
+
+typedef void (YankFn)(void *opaque);
+
+/**
+ * yank_register_instance: Register a new instance.
+ *
+ * This registers a new instance for yanking. Must be called before any yank
+ * function is registered for this instance.
+ *
+ * This function is thread-safe.
+ *
+ * @instance: The instance.
+ * @errp: Error object.
+ *
+ * Returns true on success or false if an error occured.
+ */
+bool yank_register_instance(const YankInstance *instance, Error **errp);
+
+/**
+ * yank_unregister_instance: Unregister a instance.
+ *
+ * This unregisters a instance. Must be called only after every yank function
+ * of the instance has been unregistered.
+ *
+ * This function is thread-safe.
+ *
+ * @instance: The instance.
+ */
+void yank_unregister_instance(const YankInstance *instance);
+
+/**
+ * yank_register_function: Register a yank function
+ *
+ * This registers a yank function. All limitations of qmp oob commands apply
+ * to the yank function as well. See docs/devel/qapi-code-gen.txt under
+ * "An OOB-capable command handler must satisfy the following conditions".
+ *
+ * This function is thread-safe.
+ *
+ * @instance: The instance.
+ * @func: The yank function.
+ * @opaque: Will be passed to the yank function.
+ */
+void yank_register_function(const YankInstance *instance,
+                            YankFn *func,
+                            void *opaque);
+
+/**
+ * yank_unregister_function: Unregister a yank function
+ *
+ * This unregisters a yank function.
+ *
+ * This function is thread-safe.
+ *
+ * @instance: The instance.
+ * @func: func that was passed to yank_register_function.
+ * @opaque: opaque that was passed to yank_register_function.
+ */
+void yank_unregister_function(const YankInstance *instance,
+                              YankFn *func,
+                              void *opaque);
+
+/**
+ * yank_generic_iochannel: Generic yank function for iochannel
+ *
+ * This is a generic yank function which will call qio_channel_shutdown on the
+ * provided QIOChannel.
+ *
+ * @opaque: QIOChannel to shutdown
+ */
+void yank_generic_iochannel(void *opaque);
+
+#define BLOCKDEV_YANK_INSTANCE(the_node_name) (&(YankInstance) { \
+        .type = YANK_INSTANCE_TYPE_BLOCK_NODE, \
+        .u.block_node.node_name = (the_node_name) })
+
+#define CHARDEV_YANK_INSTANCE(the_id) (&(YankInstance) { \
+        .type = YANK_INSTANCE_TYPE_CHARDEV, \
+        .u.chardev.id = (the_id) })
+
+#define MIGRATION_YANK_INSTANCE (&(YankInstance) { \
+        .type = YANK_INSTANCE_TYPE_MIGRATION })
+
+#endif