[PATCH v4 05/15] stubs: add stubs for io_uring interface

From: Stefan Hajnoczi <stefanha@redhat.com>
To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <fam@euphon.net>,
	qemu-block@nongnu.org, oleksandr@redhat.com,
	Julia Suvorova <jusual@redhat.com>,
	Markus Armbruster <armbru@redhat.com>,
	Max Reitz <mreitz@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Aarushi Mehta <mehta.aaru20@gmail.com>,
	Stefano Garzarella <sgarzare@redhat.com>
Subject: [PATCH v4 05/15] stubs: add stubs for io_uring interface
Date: Tue, 14 Jan 2020 10:59:11 +0000	[thread overview]
Message-ID: <20200114105921.131880-6-stefanha@redhat.com> (raw)
In-Reply-To: <20200114105921.131880-1-stefanha@redhat.com>

From: Aarushi Mehta <mehta.aaru20@gmail.com>

Follow linux-aio.o and stub out the block/io_uring.o APIs that will be
missing when a binary is linked with obj-util-y but without
block-util-y (e.g. vhost-user-gpu).

For example, the stubs are necessary so that a binary using util/async.o
from obj-util-y for qemu_bh_new() links successfully.  In this case
block/io_uring.o from block-util-y isn't needed and we can avoid
dragging in the block layer by linking the stubs instead.  The stub
functions never get called.

Signed-off-by: Aarushi Mehta <mehta.aaru20@gmail.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 MAINTAINERS         |  1 +
 stubs/Makefile.objs |  1 +
 stubs/io_uring.c    | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 34 insertions(+)
 create mode 100644 stubs/io_uring.c

diff --git a/MAINTAINERS b/MAINTAINERS
index dc9da76b84..ab15b76912 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2613,6 +2613,7 @@ M: Stefan Hajnoczi <stefanha@redhat.com>
 L: qemu-block@nongnu.org
 S: Maintained
 F: block/io_uring.c
+F: stubs/io_uring.c
 
 qcow2
 M: Kevin Wolf <kwolf@redhat.com>
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index 8b0ff25508..7afbe5fb61 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -13,6 +13,7 @@ stub-obj-y += iothread.o
 stub-obj-y += iothread-lock.o
 stub-obj-y += is-daemonized.o
 stub-obj-$(CONFIG_LINUX_AIO) += linux-aio.o
+stub-obj-$(CONFIG_LINUX_IO_URING) += io_uring.o
 stub-obj-y += machine-init-done.o
 stub-obj-y += migr-blocker.o
 stub-obj-y += change-state-handler.o
diff --git a/stubs/io_uring.c b/stubs/io_uring.c
new file mode 100644
index 0000000000..622d1e4648
--- /dev/null
+++ b/stubs/io_uring.c
@@ -0,0 +1,32 @@
+/*
+ * Linux io_uring support.
+ *
+ * Copyright (C) 2009 IBM, Corp.
+ * Copyright (C) 2009 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#include "qemu/osdep.h"
+#include "block/aio.h"
+#include "block/raw-aio.h"
+
+void luring_detach_aio_context(LuringState *s, AioContext *old_context)
+{
+    abort();
+}
+
+void luring_attach_aio_context(LuringState *s, AioContext *new_context)
+{
+    abort();
+}
+
+LuringState *luring_init(Error **errp)
+{
+    abort();
+}
+
+void luring_cleanup(LuringState *s)
+{
+    abort();
+}
-- 
2.24.1


