[Xen-devel] [PATCH v3 07/28] tools/libxl: Extra management APIs for the save helper

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

With migration v2, there are several moving parts needing to be
juggled at once.  This requires the error handling logic to be able to
query the state of each moving part, possibly before they have been
started, and be able to cancel them.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>

---
v3: Adjust helper_{stop,failed,done} to use libxl__save_helper_inuse()
v2: Add an _init() function which allows _inuse() to be safe to call even
    before the save helper has started.
---
 tools/libxl/libxl_create.c       |    1 +
 tools/libxl/libxl_dom.c          |    1 +
 tools/libxl/libxl_internal.h     |    9 +++++++++
 tools/libxl/libxl_save_callout.c |   22 ++++++++++++++++------
 4 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index be13204..1f43b43 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -988,6 +988,7 @@ static void domcreate_bootloader_done(libxl__egc *egc,
         rc = ERROR_INVAL;
         goto out;
     }
+    libxl__save_helper_init(&dcs->shs);
     libxl__xc_domain_restore(egc, dcs,
                              hvm, pae, superpages);
     return;
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 8642192..63e2f47 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -2117,6 +2117,7 @@ void libxl__domain_suspend(libxl__egc *egc, 
libxl__domain_suspend_state *dss)
     callbacks->switch_qemu_logdirty = 
libxl__domain_suspend_common_switch_qemu_logdirty;
     dss->shs.callbacks.save.toolstack_save = libxl__toolstack_save;
 
+    libxl__save_helper_init(&dss->shs);
     libxl__xc_domain_save(egc, dss);
     return;
 
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index e5599a3..8ce3d49 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -3272,6 +3272,15 @@ _hidden void libxl__xc_domain_restore(libxl__egc *egc,
 _hidden void libxl__xc_domain_restore_done(libxl__egc *egc, void *dcs_void,
                                            int rc, int retval, int errnoval);
 
+_hidden void libxl__save_helper_init(libxl__save_helper_state *shs);
+_hidden void libxl__save_helper_abort(libxl__egc *egc,
+                                      libxl__save_helper_state *shs);
+
+static inline bool libxl__save_helper_inuse(const libxl__save_helper_state 
*shs)
+{
+    return libxl__ev_child_inuse(&shs->child);
+}
+
 /* Each time the dm needs to be saved, we must call suspend and then save */
 _hidden int libxl__domain_suspend_device_model(libxl__gc *gc,
                                            libxl__domain_suspend_state *dss);
diff --git a/tools/libxl/libxl_save_callout.c b/tools/libxl/libxl_save_callout.c
index 1136b79..0fb1fdc 100644
--- a/tools/libxl/libxl_save_callout.c
+++ b/tools/libxl/libxl_save_callout.c
@@ -146,6 +146,13 @@ void 
libxl__xc_domain_saverestore_async_callback_done(libxl__egc *egc,
     shs->egc = 0;
 }
 
+void libxl__save_helper_init(libxl__save_helper_state *shs)
+{
+    libxl__ao_abortable_init(&shs->abrt);
+    libxl__ev_fd_init(&shs->readable);
+    libxl__ev_child_init(&shs->child);
+}
+
 /*----- helper execution -----*/
 
 static void run_helper(libxl__egc *egc, libxl__save_helper_state *shs,
@@ -167,9 +174,6 @@ static void run_helper(libxl__egc *egc, 
libxl__save_helper_state *shs,
     shs->rc = 0;
     shs->completed = 0;
     shs->pipes[0] = shs->pipes[1] = 0;
-    libxl__ao_abortable_init(&shs->abrt);
-    libxl__ev_fd_init(&shs->readable);
-    libxl__ev_child_init(&shs->child);
 
     shs->abrt.ao = shs->ao;
     shs->abrt.callback = helper_stop;
@@ -255,7 +259,7 @@ static void helper_failed(libxl__egc *egc, 
libxl__save_helper_state *shs,
 
     libxl__ev_fd_deregister(gc, &shs->readable);
 
-    if (!libxl__ev_child_inuse(&shs->child)) {
+    if (!libxl__save_helper_inuse(shs)) {
         helper_done(egc, shs);
         return;
     }
@@ -268,7 +272,7 @@ static void helper_stop(libxl__egc *egc, 
libxl__ao_abortable *abrt, int rc)
     libxl__save_helper_state *shs = CONTAINER_OF(abrt, *shs, abrt);
     STATE_AO_GC(shs->ao);
 
-    if (!libxl__ev_child_inuse(&shs->child)) {
+    if (!libxl__save_helper_inuse(shs)) {
         helper_failed(egc, shs, rc);
         return;
     }
@@ -279,6 +283,12 @@ static void helper_stop(libxl__egc *egc, 
libxl__ao_abortable *abrt, int rc)
     libxl__kill(gc, shs->child.pid, SIGTERM, "save/restore helper");
 }
 
+void libxl__save_helper_abort(libxl__egc *egc,
+                              libxl__save_helper_state *shs)
+{
+    helper_stop(egc, &shs->abrt, ERROR_FAIL);
+}
+
 static void helper_stdout_readable(libxl__egc *egc, libxl__ev_fd *ev,
                                    int fd, short events, short revents)
 {
@@ -356,7 +366,7 @@ static void helper_done(libxl__egc *egc, 
libxl__save_helper_state *shs)
     libxl__ev_fd_deregister(gc, &shs->readable);
     libxl__carefd_close(shs->pipes[0]);  shs->pipes[0] = 0;
     libxl__carefd_close(shs->pipes[1]);  shs->pipes[1] = 0;
-    assert(!libxl__ev_child_inuse(&shs->child));
+    assert(!libxl__save_helper_inuse(shs));
     if (shs->toolstack_data_file) fclose(shs->toolstack_data_file);
 
     shs->egc = egc;
-- 
1.7.10.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel