libxl: convert console callback to libxl_asyncprogress_how

Remove the old console callback.  (Its reentrancy properties were
troublesome: in principle, the event loop might be reentered during
the callback, and the libxl__domain_create_state swept out from under
the feet of the domain creation.)

As a side effect of the new code arrangements, the console callback
for non-bootloader-using PV guests now occurs near the end of domain
creation, in the same place as for HVM guests, rather than near the
start.

The new arrangements should in principle mean that by the time the
console is described as ready by the callback, the xenstore key is
indeed ready.  So in the future the timeout might be removed from
the console client.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>

1 files changed, 34 insertions, 25 deletions

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 63cb430fa1..14721eb50a 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -569,10 +569,15 @@ static int store_libxl_entry(libxl__gc *gc, uint32_t domid,
 static void domcreate_devmodel_started(libxl__egc *egc,
                                        libxl__dm_spawn_state *dmss,
                                        int rc);
+static void domcreate_bootloader_console_available(libxl__egc *egc,
+                                                   libxl__bootloader_state *bl);
 static void domcreate_bootloader_done(libxl__egc *egc,
                                       libxl__bootloader_state *bl,
                                       int rc);
 
+static void domcreate_console_available(libxl__egc *egc,
+                                        libxl__domain_create_state *dcs);
+
 /* Our own function to clean up and call the user's callback.
  * The final call in the sequence. */
 static void domcreate_complete(libxl__egc *egc,
@@ -590,8 +595,6 @@ static void initiate_domain_create(libxl__egc *egc,
     /* convenience aliases */
     libxl_domain_config *const d_config = dcs->guest_config;
     const int restore_fd = dcs->restore_fd;
-    const libxl_console_ready cb = dcs->console_cb;
-    void *const priv = dcs->console_cb_priv;
     memset(&dcs->build_state, 0, sizeof(dcs->build_state));
 
     domid = 0;
@@ -610,11 +613,6 @@ static void initiate_domain_create(libxl__egc *egc,
     dcs->guest_domid = domid;
     dcs->dmss.dm.guest_domid = 0; /* means we haven't spawned */
 
-    if ( d_config->c_info.type == LIBXL_DOMAIN_TYPE_PV && cb ) {
-        ret = (*cb)(ctx, domid, priv);
-        if (ret) goto error_out;
-    }
-
     ret = libxl__domain_build_info_setdefault(gc, &d_config->b_info);
     if (ret) goto error_out;
 
@@ -629,6 +627,7 @@ static void initiate_domain_create(libxl__egc *egc,
 
     if (restore_fd < 0 && bootdisk) {
         dcs->bl.callback = domcreate_bootloader_done;
+        dcs->bl.console_available = domcreate_bootloader_console_available;
         dcs->bl.info = &d_config->b_info,
         dcs->bl.disk = bootdisk;
         dcs->bl.domid = dcs->guest_domid;
@@ -644,6 +643,21 @@ error_out:
     domcreate_complete(egc, dcs, ret);
 }
 
+static void domcreate_bootloader_console_available(libxl__egc *egc,
+                                                   libxl__bootloader_state *bl)
+{
+    libxl__domain_create_state *dcs = CONTAINER_OF(bl, *dcs, bl);
+    STATE_AO_GC(bl->ao);
+    domcreate_console_available(egc, dcs);
+}
+
+static void domcreate_console_available(libxl__egc *egc,
+                                        libxl__domain_create_state *dcs) {
+    libxl__ao_progress_report(egc, dcs->ao, &dcs->aop_console_how,
+                              NEW_EVENT(egc, DOMAIN_CREATE_CONSOLE_AVAILABLE,
+                                        dcs->guest_domid));
+}
+
 static void domcreate_bootloader_done(libxl__egc *egc,
                                       libxl__bootloader_state *bl,
                                       int ret)
@@ -779,8 +793,6 @@ static void domcreate_devmodel_started(libxl__egc *egc,
 
     /* convenience aliases */
     libxl_domain_config *const d_config = dcs->guest_config;
-    const libxl_console_ready cb = dcs->console_cb;
-    void *const priv = dcs->console_cb_priv;
 
     if (ret) {
         LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
@@ -818,12 +830,7 @@ static void domcreate_devmodel_started(libxl__egc *egc,
             goto error_out;
         }
     }
-    if ( cb && (d_config->c_info.type == LIBXL_DOMAIN_TYPE_HVM ||
-                (d_config->c_info.type == LIBXL_DOMAIN_TYPE_PV &&
-                 d_config->b_info.u.pv.bootloader ))) {
-        ret = (*cb)(ctx, domid, priv);
-        if (ret) goto error_out;
-    }
+    domcreate_console_available(egc, dcs);
 
     domcreate_complete(egc, dcs, 0);
     return;
@@ -863,8 +870,9 @@ static void domain_create_cb(libxl__egc *egc,
                              int rc, uint32_t domid);
 
 static int do_domain_create(libxl_ctx *ctx, libxl_domain_config *d_config,
-                            libxl_console_ready cb, void *priv, uint32_t *domid,
-                            int restore_fd, const libxl_asyncop_how *ao_how)
+                            uint32_t *domid,
+                            int restore_fd, const libxl_asyncop_how *ao_how,
+                            const libxl_asyncprogress_how *aop_console_how)
 {
     AO_CREATE(ctx, 0, ao_how);
     libxl__app_domain_create_state *cdcs;
@@ -873,9 +881,8 @@ static int do_domain_create(libxl_ctx *ctx, libxl_domain_config *d_config,
     cdcs->dcs.ao = ao;
     cdcs->dcs.guest_config = d_config;
     cdcs->dcs.restore_fd = restore_fd;
-    cdcs->dcs.console_cb = cb;
-    cdcs->dcs.console_cb_priv = priv;
     cdcs->dcs.callback = domain_create_cb;
+    libxl__ao_progress_gethow(&cdcs->dcs.aop_console_how, aop_console_how);
     cdcs->domid_out = domid;
 
     initiate_domain_create(egc, &cdcs->dcs);
@@ -897,19 +904,21 @@ static void domain_create_cb(libxl__egc *egc,
 }
     
 int libxl_domain_create_new(libxl_ctx *ctx, libxl_domain_config *d_config,
-                            libxl_console_ready cb, void *priv,
                             uint32_t *domid,
-                            const libxl_asyncop_how *ao_how)
+                            const libxl_asyncop_how *ao_how,
+                            const libxl_asyncprogress_how *aop_console_how)
 {
-    return do_domain_create(ctx, d_config, cb, priv, domid, -1, ao_how);
+    return do_domain_create(ctx, d_config, domid, -1,
+                            ao_how, aop_console_how);
 }
 
 int libxl_domain_create_restore(libxl_ctx *ctx, libxl_domain_config *d_config,
-                                libxl_console_ready cb, void *priv,
                                 uint32_t *domid, int restore_fd,
-                                const libxl_asyncop_how *ao_how)
+                                const libxl_asyncop_how *ao_how,
+                            const libxl_asyncprogress_how *aop_console_how)
 {
-    return do_domain_create(ctx, d_config, cb, priv, domid, restore_fd, ao_how);
+    return do_domain_create(ctx, d_config, domid, restore_fd,
+                            ao_how, aop_console_how);
 }
 
 /*