[Xen-devel] [XEN PATCH] libxl: wait for console path before firing console_available

[Paweł Marczewski <pawel@xxxxxxxxxxxxxxxxxxxxxx>]

If we skip the bootloader, the TTY path will be set for xenconsoled.
However, there is no guarantee that this will happen by the time we
want to call the console_available callback, so we have to wait.

Signed-off-by: Paweł Marczewski <pawel@xxxxxxxxxxxxxxxxxxxxxx>
---
 tools/libxl/libxl_create.c   | 33 ++++++++++++++++++++++++++++++---
 tools/libxl/libxl_internal.h |  1 +
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 3a7364e2ac..53f2886544 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -1190,6 +1190,21 @@ static void domcreate_console_available(libxl__egc *egc,
                                         dcs->aop_console_how.for_event));
 }
 
+static void console_watch_callback(libxl__egc *egc, libxl__ev_xswatch *watch,
+                                   const char *watch_path,
+                                   const char *event_path) {
+    EGC_GC;
+    libxl__domain_create_state *dcs = CONTAINER_OF(watch, *dcs, console_watch);
+    char *dompath = libxl__xs_get_dompath(gc, dcs->guest_domid);
+    char *tty_path = GCSPRINTF("%s/console/tty", dompath);
+    char *tty = libxl__xs_read(gc, XBT_NULL, tty_path);
+
+    if (tty && tty[0] != '\0') {
+        domcreate_console_available(egc, dcs);
+        domcreate_complete(egc, dcs, 0);
+    }
+}
+
 static void domcreate_bootloader_done(libxl__egc *egc,
                                       libxl__bootloader_state *bl,
                                       int rc)
@@ -1705,6 +1720,8 @@ static void domcreate_attach_devices(libxl__egc *egc,
     int domid = dcs->guest_domid;
     libxl_domain_config *const d_config = dcs->guest_config;
     const libxl__device_type *dt;
+    char *tty_path;
+    int rc;
 
     if (ret) {
         LOGD(ERROR, domid, "unable to add %s devices",
@@ -1728,9 +1745,15 @@ static void domcreate_attach_devices(libxl__egc *egc,
         return;
     }
 
-    domcreate_console_available(egc, dcs);
-
-    domcreate_complete(egc, dcs, 0);
+    tty_path = GCSPRINTF("%s/console/tty", libxl__xs_get_dompath(gc, domid));
+    rc = libxl__ev_xswatch_register(gc, &dcs->console_watch,
+                                    console_watch_callback,
+                                    tty_path);
+    if (rc) {
+        LOG(ERROR, "unable to set up watch for console path: %s",
+            tty_path);
+        goto error_out;
+    }
 
     return;
 
@@ -1747,6 +1770,9 @@ static void domcreate_complete(libxl__egc *egc,
     libxl_domain_config *const d_config = dcs->guest_config;
     libxl_domain_config *d_config_saved = &dcs->guest_config_saved;
 
+    if (libxl__ev_xswatch_isregistered(&dcs->console_watch))
+        libxl__ev_xswatch_deregister(gc, &dcs->console_watch);
+
     libxl__domain_build_state_dispose(&dcs->build_state);
 
     if (!rc && d_config->b_info.exec_ssidref)
@@ -1861,6 +1887,7 @@ static int do_domain_create(libxl_ctx *ctx, 
libxl_domain_config *d_config,
 
     libxl__ao_progress_gethow(&cdcs->dcs.aop_console_how, aop_console_how);
     cdcs->domid_out = domid;
+    libxl__ev_xswatch_init(&cdcs->dcs.console_watch);
 
     initiate_domain_create(egc, &cdcs->dcs);
 
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index dd3c08bc14..fa666cbe0c 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -4177,6 +4177,7 @@ struct libxl__domain_create_state {
     /* necessary if the domain creation failed and we have to destroy it */
     libxl__domain_destroy_state dds;
     libxl__multidev multidev;
+    libxl__ev_xswatch console_watch;
 };
 
 _hidden int libxl__device_nic_set_devids(libxl__gc *gc,
-- 
2.21.1


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