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Re: [PATCH v2 26/29] tools/xenstored: mount 9pfs device in stubdom



Hi Juergen,

On 10/11/2023 16:08, Juergen Gross wrote:
diff --git a/tools/xenstored/domain.c b/tools/xenstored/domain.c
index 162b87b460..4263c1360f 100644
--- a/tools/xenstored/domain.c
+++ b/tools/xenstored/domain.c
@@ -1236,6 +1236,8 @@ void stubdom_init(void)
                barf_perror("Failed to initialize stubdom");
xenevtchn_notify(xce_handle, stubdom->port);
+
+       mount_9pfs();
  #endif
  }
diff --git a/tools/xenstored/minios.c b/tools/xenstored/minios.c
index 202d70387a..fddbede869 100644
--- a/tools/xenstored/minios.c
+++ b/tools/xenstored/minios.c
@@ -19,8 +19,16 @@
  #include <sys/mman.h>
  #include "core.h"
  #include <xen/grant_table.h>
+#include <mini-os/9pfront.h>
  #include <mini-os/events.h>
  #include <mini-os/gnttab.h>
+#include <mini-os/sched.h>
+#include <mini-os/xenbus.h>
+#include <mini-os/xmalloc.h>
+
+#define P9_STATE_PATH  "device/9pfs/0/state"
+
+static void *p9_device;
void write_pidfile(const char *pidfile)
  {
@@ -62,3 +70,31 @@ void early_init(void)
        if (stub_domid == DOMID_INVALID)
                barf("could not get own domid");
  }
+
+static void mount_thread(void *p)
+{
+       xenbus_event_queue events = NULL;
+       char *err;
+       char *dummy;
+
+       free(xenbus_watch_path_token(XBT_NIL, P9_STATE_PATH, "9pfs", &events));

AFAICT, xenbus_watch_path_token() can fail. I agree this is unlikely, but if it fails, then it would be useful to get some logs. Otherwise...

+
+       for (;;) {

... this loop would be infinite.

+               xenbus_wait_for_watch(&events);
+               err = xenbus_read(XBT_NIL, P9_STATE_PATH, &dummy);

Can you explain why don't care about the value of the node?

+               if (!err)
+                       break;
+               free(err);
+       }
+
+       free(dummy);
+
+       free(xenbus_unwatch_path_token(XBT_NIL, P9_STATE_PATH, "9pfs"));

xenbus_unwatch_path_token() could technically fails. It would be helpful to print a message.

+
+       p9_device = init_9pfront(0, XENSTORE_LIB_DIR);
+}
+
+void mount_9pfs(void)
+{
+       create_thread("mount-9pfs", mount_thread, NULL);
+}

Cheers,

--
Julien Grall



 


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