minios: refactor xenbus state machine

Implement xenbus_wait_for_state_change and xenbus_switch_state and
change the various frontends to use the two functions and do proper
error checking.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 56 insertions, 15 deletions

diff --git a/extras/mini-os/pcifront.c b/extras/mini-os/pcifront.c
index 5b68d86b56..70ea89b82d 100644
--- a/extras/mini-os/pcifront.c
+++ b/extras/mini-os/pcifront.c
@@ -111,9 +111,12 @@ again:
         goto abort_transaction;
     }
 
-    err = xenbus_printf(xbt, nodename, "state", "%u",
-            3); /* initialised */
-
+    snprintf(path, sizeof(path), "%s/state", nodename);
+    err = xenbus_switch_state(xbt, path, XenbusStateInitialised);
+    if (err) {
+        message = "switching state";
+        goto abort_transaction;
+    }
 
     err = xenbus_transaction_end(xbt, 0, &retry);
     if (retry) {
@@ -140,13 +143,29 @@ done:
 
     {
         char path[strlen(dev->backend) + 1 + 5 + 1];
+        char frontpath[strlen(nodename) + 1 + 5 + 1];
+        XenbusState state;
         snprintf(path, sizeof(path), "%s/state", dev->backend);
 
         xenbus_watch_path_token(XBT_NIL, path, path, &dev->events);
 
-        xenbus_wait_for_value(path, "4", &dev->events);
+        err = NULL;
+        state = xenbus_read_integer(path);
+        while (err == NULL && state < XenbusStateConnected)
+            err = xenbus_wait_for_state_change(path, &state, &dev->events);
+        if (state != XenbusStateConnected) {
+            printk("backend not avalable, state=%d\n", state);
+            xenbus_unwatch_path(XBT_NIL, path);
+            goto error;
+        }
 
-        xenbus_printf(xbt, nodename, "state", "%u", 4); /* connected */
+        snprintf(frontpath, sizeof(frontpath), "%s/state", nodename);
+        if ((err = xenbus_switch_state(XBT_NIL, frontpath, XenbusStateConnected))
+            != NULL) {
+            printk("error switching state %s\n", err);
+            xenbus_unwatch_path(XBT_NIL, path);
+            goto error;
+        }
     }
     unmask_evtchn(dev->evtchn);
 
@@ -190,23 +209,45 @@ void pcifront_scan(struct pcifront_dev *dev, void (*func)(unsigned int domain, u
 
 void shutdown_pcifront(struct pcifront_dev *dev)
 {
-    char* err;
-    char *nodename = dev->nodename;
+    char* err = NULL;
+    XenbusState state;
 
     char path[strlen(dev->backend) + 1 + 5 + 1];
+    char nodename[strlen(dev->nodename) + 1 + 5 + 1];
 
     printk("close pci: backend at %s\n",dev->backend);
 
     snprintf(path, sizeof(path), "%s/state", dev->backend);
-    err = xenbus_printf(XBT_NIL, nodename, "state", "%u", 5); /* closing */
-    xenbus_wait_for_value(path, "5", &dev->events);
-
-    err = xenbus_printf(XBT_NIL, nodename, "state", "%u", 6);
-    xenbus_wait_for_value(path, "6", &dev->events);
-
-    err = xenbus_printf(XBT_NIL, nodename, "state", "%u", 1);
-    xenbus_wait_for_value(path, "2", &dev->events);
+    snprintf(nodename, sizeof(nodename), "%s/state", dev->nodename);
+    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateClosing)) != NULL) {
+        printk("shutdown_pcifront: error changing state to %d: %s\n",
+                XenbusStateClosing, err);
+        goto close_pcifront;
+    }
+    state = xenbus_read_integer(path);
+    while (err == NULL && state < XenbusStateClosing)
+        err = xenbus_wait_for_state_change(path, &state, &dev->events);
+
+    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateClosed)) != NULL) {
+        printk("shutdown_pcifront: error changing state to %d: %s\n",
+                XenbusStateClosed, err);
+        goto close_pcifront;
+    }
+    state = xenbus_read_integer(path);
+    if (state < XenbusStateClosed)
+        xenbus_wait_for_state_change(path, &state, &dev->events);
+
+    if ((err = xenbus_switch_state(XBT_NIL, nodename, XenbusStateInitialising)) != NULL) {
+        printk("shutdown_pcifront: error changing state to %d: %s\n",
+                XenbusStateInitialising, err);
+        goto close_pcifront;
+    }
+    err = NULL;
+    state = xenbus_read_integer(path);
+    while (err == NULL && (state < XenbusStateInitWait || state >= XenbusStateClosed))
+        err = xenbus_wait_for_state_change(path, &state, &dev->events);
 
+close_pcifront:
     xenbus_unwatch_path(XBT_NIL, path);
 
     snprintf(path, sizeof(path), "%s/info-ref", nodename);