[PATCH 13/23] libxl: suspend: Async libxl__domain_suspend_callback

[Ian Jackson <ian.jackson@eu.citrix.com>]

Mark the suspend callback libxl__domain_suspend_callback as
asynchronous in the helper stub generator (libxl_save_msgs_gen.pl).
We are going to want to provide an asynchronous version of this
function to get rid of the usleeps and waiting loops in the suspend
code.

libxl__domain_suspend_common_callback, the common synchronous core,
which used to be provided directly as the callback function for the
helper machinery, becomes libxl__domain_suspend_callback_common.  It
can now take a typesafe parameter.

For now, provide two very similar asynchronous wrappers for it.  Each
is a simple function which contains only boilerplate, calls the common
synchronous core, and returns the asynchronous response.

Essentially, we have just moved (in the case of suspend callbacks) the
call site of libxl__srm_callout_callback_complete.  It was in the
switch statement in the autogenerated _libxl_save_msgs_callout.c, and
is now in the handwritten libxl_dom.c.

No functional change.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Cc: Ian Campbell <ian.campbell@citrix.com>

---
v2: Commit message mentions usleeps, not Remus, as motivation.
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 tools/libxl/libxl_dom.c            |   25 +++++++++++++++++++------
 tools/libxl/libxl_internal.h       |    2 +-
 tools/libxl/libxl_save_msgs_gen.pl |    2 +-
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 48a4b8e..1c0f04f 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -1020,10 +1020,8 @@ int libxl__domain_resume_device_model(libxl__gc *gc, uint32_t domid)
     return 0;
 }
 
-int libxl__domain_suspend_common_callback(void *user)
+int libxl__domain_suspend_callback_common(libxl__domain_suspend_state *dss)
 {
-    libxl__save_helper_state *shs = user;
-    libxl__domain_suspend_state *dss = CONTAINER_OF(shs, *dss, shs);
     STATE_AO_GC(dss->ao);
     unsigned long hvm_s_state = 0, hvm_pvdrv = 0;
     int ret;
@@ -1242,12 +1240,27 @@ int libxl__toolstack_save(uint32_t domid, uint8_t **buf,
     return 0;
 }
 
+static void libxl__domain_suspend_callback(void *data)
+{
+    libxl__save_helper_state *shs = data;
+    libxl__egc *egc = shs->egc;
+    libxl__domain_suspend_state *dss = CONTAINER_OF(shs, *dss, shs);
+
+    int ok = libxl__domain_suspend_callback_common(dss);
+    libxl__xc_domain_saverestore_async_callback_done(egc, shs, ok);
+}
+
 /*----- remus callbacks -----*/
 
-static int libxl__remus_domain_suspend_callback(void *data)
+static void libxl__remus_domain_suspend_callback(void *data)
 {
+    libxl__save_helper_state *shs = data;
+    libxl__egc *egc = shs->egc;
+    libxl__domain_suspend_state *dss = CONTAINER_OF(shs, *dss, shs);
+
     /* REMUS TODO: Issue disk and network checkpoint reqs. */
-    return libxl__domain_suspend_common_callback(data);
+    int ok = libxl__domain_suspend_callback_common(dss);
+    libxl__xc_domain_saverestore_async_callback_done(egc, shs, ok);
 }
 
 static int libxl__remus_domain_resume_callback(void *data)
@@ -1373,7 +1386,7 @@ void libxl__domain_suspend(libxl__egc *egc, libxl__domain_suspend_state *dss)
         callbacks->postcopy = libxl__remus_domain_resume_callback;
         callbacks->checkpoint = libxl__remus_domain_checkpoint_callback;
     } else
-        callbacks->suspend = libxl__domain_suspend_common_callback;
+        callbacks->suspend = libxl__domain_suspend_callback;
 
     callbacks->switch_qemu_logdirty = libxl__domain_suspend_common_switch_qemu_logdirty;
     dss->shs.callbacks.save.toolstack_save = libxl__toolstack_save;
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 01873c0..9b9264e 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2705,7 +2705,7 @@ _hidden void libxl__xc_domain_save_done(libxl__egc*, void *dss_void,
 void libxl__xc_domain_saverestore_async_callback_done(libxl__egc *egc,
                            libxl__save_helper_state *shs, int return_value);
 
-_hidden int libxl__domain_suspend_common_callback(void *data);
+_hidden int libxl__domain_suspend_callback_common(libxl__domain_suspend_state*);
 _hidden void libxl__domain_suspend_common_switch_qemu_logdirty
                                (int domid, unsigned int enable, void *data);
 _hidden int libxl__toolstack_save(uint32_t domid, uint8_t **buf,
diff --git a/tools/libxl/libxl_save_msgs_gen.pl b/tools/libxl/libxl_save_msgs_gen.pl
index ee126c7..3c6bd57 100755
--- a/tools/libxl/libxl_save_msgs_gen.pl
+++ b/tools/libxl/libxl_save_msgs_gen.pl
@@ -23,7 +23,7 @@ our @msgs = (
                                                  STRING doing_what),
                                                 'unsigned long', 'done',
                                                 'unsigned long', 'total'] ],
-    [  3, 'scxW',   "suspend", [] ],         
+    [  3, 'scxA',   "suspend", [] ],         
     [  4, 'scxW',   "postcopy", [] ],        
     [  5, 'scxA',   "checkpoint", [] ],      
     [  6, 'scxA',   "switch_qemu_logdirty",  [qw(int domid
-- 
1.7.10.4