[Xen-devel] [PATCH v4 07/11] libxl: Make killing of device model asynchronous

[George Dunlap <george.dunlap@xxxxxxxxxx>]

Or at least, give it an asynchronous interface so that we can make it
actually asynchronous in subsequent patches.

Create state structures and callback function signatures.  Add the
state structure to libxl__destroy_domid_state.  Break
libxl__destroy_domid down into two functions.

No functional change intended.

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxx>
Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
v2:
- Note that libxl__devicemodel_destroy_cb may be called reentrantly

NB that I retain the comment before libxl__destroy_device_model, in
spite of the fact that it looks "pointless", to separate it logically
from the previous prototype.

CC: Ian Jackson <ian.jackson@xxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl_dm.c       | 11 +++++++---
 tools/libxl/libxl_domain.c   | 40 ++++++++++++++++++++++++++++--------
 tools/libxl/libxl_internal.h | 20 ++++++++++++++++--
 3 files changed, 58 insertions(+), 13 deletions(-)

diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 450433452d..ca59df33fe 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -2696,19 +2696,24 @@ out:
     return rc;
 }
 
-int libxl__destroy_device_model(libxl__gc *gc, uint32_t domid)
+void libxl__destroy_device_model(libxl__egc *egc,
+                                 libxl__destroy_devicemodel_state *ddms)
 {
+    STATE_AO_GC(ddms->ao);
     int rc;
+    int domid = ddms->domid;
     char *path = DEVICE_MODEL_XS_PATH(gc, LIBXL_TOOLSTACK_DOMID, domid, "");
+
     if (!xs_rm(CTX->xsh, XBT_NULL, path))
         LOGD(ERROR, domid, "xs_rm failed for %s", path);
+
     /* We should try to destroy the device model anyway. */
     rc = kill_device_model(gc,
               GCSPRINTF("/local/domain/%d/image/device-model-pid", domid));
-    
+
     libxl__qmp_cleanup(gc, domid);
 
-    return rc;
+    ddms->callback(egc, ddms, rc);
 }
 
 /* Return 0 if no dm needed, 1 if needed and <0 if error. */
diff --git a/tools/libxl/libxl_domain.c b/tools/libxl/libxl_domain.c
index d46b97dedf..0ce1ba1327 100644
--- a/tools/libxl/libxl_domain.c
+++ b/tools/libxl/libxl_domain.c
@@ -1008,6 +1008,10 @@ static void destroy_finish_check(libxl__egc *egc,
 }
 
 /* Callbacks for libxl__destroy_domid */
+static void dm_destroy_cb(libxl__egc *egc,
+                          libxl__destroy_devicemodel_state *ddms,
+                          int rc);
+
 static void devices_destroy_cb(libxl__egc *egc,
                                libxl__devices_remove_state *drs,
                                int rc);
@@ -1066,16 +1070,18 @@ void libxl__destroy_domid(libxl__egc *egc, 
libxl__destroy_domid_state *dis)
     if (rc < 0) {
         LOGEVD(ERROR, rc, domid, "xc_domain_pause failed");
     }
+
     if (dm_present) {
-        if (libxl__destroy_device_model(gc, domid) < 0)
-            LOGD(ERROR, domid, "libxl__destroy_device_model failed");
+        dis->ddms.ao = ao;
+        dis->ddms.domid = domid;
+        dis->ddms.callback = dm_destroy_cb;
+
+        libxl__destroy_device_model(egc, &dis->ddms);
+        return;
+    } else {
+        dm_destroy_cb(egc, &dis->ddms, 0);
+        return;
     }
-    dis->drs.ao = ao;
-    dis->drs.domid = domid;
-    dis->drs.callback = devices_destroy_cb;
-    dis->drs.force = 1;
-    libxl__devices_destroy(egc, &dis->drs);
-    return;
 
 out:
     assert(rc);
@@ -1083,6 +1089,24 @@ out:
     return;
 }
 
+static void dm_destroy_cb(libxl__egc *egc,
+                          libxl__destroy_devicemodel_state *ddms,
+                          int rc)
+{
+    libxl__destroy_domid_state *dis = CONTAINER_OF(ddms, *dis, ddms);
+    STATE_AO_GC(dis->ao);
+    uint32_t domid = dis->domid;
+
+    if (rc < 0)
+        LOGD(ERROR, domid, "libxl__destroy_device_model failed");
+
+    dis->drs.ao = ao;
+    dis->drs.domid = domid;
+    dis->drs.callback = devices_destroy_cb;
+    dis->drs.force = 1;
+    libxl__devices_destroy(egc, &dis->drs);
+}
+
 static void devices_destroy_cb(libxl__egc *egc,
                                libxl__devices_remove_state *drs,
                                int rc)
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index b147f3803c..f9e0bf6578 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1705,8 +1705,6 @@ _hidden int 
libxl__wait_for_device_model_deprecated(libxl__gc *gc,
                                                       void *userdata),
                                 void *check_callback_userdata);
 
-_hidden int libxl__destroy_device_model(libxl__gc *gc, uint32_t domid);
-
 _hidden const libxl_vnc_info *libxl__dm_vnc(const libxl_domain_config *g_cfg);
 
 _hidden char *libxl__abs_path(libxl__gc *gc, const char *s, const char *path);
@@ -3672,6 +3670,7 @@ extern const struct libxl_device_type *device_type_tbl[];
 
 typedef struct libxl__domain_destroy_state libxl__domain_destroy_state;
 typedef struct libxl__destroy_domid_state libxl__destroy_domid_state;
+typedef struct libxl__destroy_devicemodel_state 
libxl__destroy_devicemodel_state;
 typedef struct libxl__devices_remove_state libxl__devices_remove_state;
 
 typedef void libxl__domain_destroy_cb(libxl__egc *egc,
@@ -3682,6 +3681,10 @@ typedef void libxl__domid_destroy_cb(libxl__egc *egc,
                                      libxl__destroy_domid_state *dis,
                                      int rc);
 
+typedef void libxl__devicemodel_destroy_cb(libxl__egc *egc,
+                                     libxl__destroy_devicemodel_state *ddms,
+                                     int rc);
+
 typedef void libxl__devices_remove_callback(libxl__egc *egc,
                                             libxl__devices_remove_state *drs,
                                             int rc);
@@ -3697,6 +3700,14 @@ struct libxl__devices_remove_state {
     int num_devices;
 };
 
+struct libxl__destroy_devicemodel_state {
+    /* filled in by user */
+    libxl__ao *ao;
+    uint32_t domid;
+    libxl__devicemodel_destroy_cb *callback; /* May be called re-entrantly */
+    /* private to implementation */
+};
+
 struct libxl__destroy_domid_state {
     /* filled in by user */
     libxl__ao *ao;
@@ -3704,6 +3715,7 @@ struct libxl__destroy_domid_state {
     libxl__domid_destroy_cb *callback;
     /* private to implementation */
     libxl__devices_remove_state drs;
+    libxl__destroy_devicemodel_state ddms;
     libxl__ev_child destroyer;
     bool soft_reset;
 };
@@ -3735,6 +3747,10 @@ _hidden void libxl__domain_destroy(libxl__egc *egc,
 _hidden void libxl__destroy_domid(libxl__egc *egc,
                                   libxl__destroy_domid_state *dis);
 
+/* Used to detroy the device model */
+_hidden void libxl__destroy_device_model(libxl__egc *egc,
+                                         libxl__destroy_devicemodel_state 
*ddms);
+
 /* Entry point for devices destruction */
 _hidden void libxl__devices_destroy(libxl__egc *egc,
                                     libxl__devices_remove_state *drs);
-- 
2.19.2


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