[Xen-devel] [PATCH 6 of 6] libxl: use hotplug-status to synchronize the destruction of block devices

[Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>]

# HG changeset patch
# User Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>
# Date 1316692512 -7200
# Node ID 9e9c68768676b0e1c9c76599e00d0922c6184602
# Parent  a5c9a6083bef9d4789a0194389db234740cd6005
libxl: use hotplug-status to synchronize the destruction of block devices

Use hotplug-status to synchronize the destruction of vbd devices instead of 
state, which did not reflect when the hotplug script had been executed.

Signed-off-by: Roger Pau Monne <roger.pau@xxxxxxxxxxxxx>

diff -r a5c9a6083bef -r 9e9c68768676 tools/libxl/libxl_device.c
--- a/tools/libxl/libxl_device.c        Thu Sep 22 13:55:03 2011 +0200
+++ b/tools/libxl/libxl_device.c        Thu Sep 22 13:55:12 2011 +0200
@@ -371,14 +371,26 @@ int libxl__device_destroy(libxl__gc *gc,
     libxl_ctx *ctx = libxl__gc_owner(gc);
     xs_transaction_t t;
     char *state_path = libxl__sprintf(gc, "%s/state", be_path);
+    char *hotplug_path = libxl__sprintf(gc, "%s/hotplug-status", be_path);
     char *state = libxl__xs_read(gc, XBT_NULL, state_path);
+    char *hotplug = libxl__xs_read(gc, XBT_NULL, hotplug_path);
     int rc = 0;
 
     if (!state)
         goto out;
-    if (atoi(state) != 4) {
-        xs_rm(ctx->xsh, XBT_NULL, be_path);
-        goto out;
+
+    if (!strstr(be_path, string_of_kinds[DEVICE_VBD])) {
+        if (atoi(state) != 4) {
+            xs_rm(ctx->xsh, XBT_NULL, be_path);
+            goto out;
+        }
+    } else {
+        if (!hotplug)
+            goto out;
+        if (!strcmp(hotplug, "disconnected")) {
+            xs_rm(ctx->xsh, XBT_NULL, be_path);
+            goto out;
+        }
     }
 
 retry_transaction:
@@ -394,8 +406,13 @@ retry_transaction:
         }
     }
     if (!force) {
-        xs_watch(ctx->xsh, state_path, be_path);
-        rc = 1;
+        if (strstr(be_path, string_of_kinds[DEVICE_VBD])) {
+            xs_watch(ctx->xsh, hotplug_path, be_path);
+            rc = 1;
+        } else {
+            xs_watch(ctx->xsh, state_path, be_path);
+            rc = 1;
+        }
     } else {
         xs_rm(ctx->xsh, XBT_NULL, be_path);
     }
@@ -410,6 +427,7 @@ static int wait_for_dev_destroy(libxl__g
     unsigned int n;
     fd_set rfds;
     char **l1 = NULL;
+    char *state, *hotplug;
 
     rc = 1;
     nfds = xs_fileno(ctx->xsh) + 1;
@@ -418,12 +436,26 @@ static int wait_for_dev_destroy(libxl__g
     if (select(nfds, &rfds, NULL, NULL, tv) > 0) {
         l1 = xs_read_watch(ctx->xsh, &n);
         if (l1 != NULL) {
-            char *state = libxl__xs_read(gc, XBT_NULL, l1[XS_WATCH_PATH]);
-            if (!state || atoi(state) == 6) {
-                xs_unwatch(ctx->xsh, l1[0], l1[1]);
-                xs_rm(ctx->xsh, XBT_NULL, l1[XS_WATCH_TOKEN]);
-                LIBXL__LOG(ctx, LIBXL__LOG_DEBUG, "Destroyed device backend at 
%s", l1[XS_WATCH_TOKEN]);
-                rc = 0;
+            if (strstr(l1[XS_WATCH_PATH], "hotplug-status")) {
+                hotplug = libxl__xs_read(gc, XBT_NULL, l1[XS_WATCH_PATH]);
+                if (!hotplug || !strcmp(hotplug, "disconnected")) {
+                    xs_unwatch(ctx->xsh, l1[0], l1[1]);
+                    xs_rm(ctx->xsh, XBT_NULL, l1[XS_WATCH_TOKEN]);
+                    LIBXL__LOG(ctx, LIBXL__LOG_DEBUG,
+                        "Destroyed device backend at %s hotplug-status: %s",
+                        l1[XS_WATCH_TOKEN], hotplug);
+                    rc = 0;
+                }
+            } else {
+                state = libxl__xs_read(gc, XBT_NULL, l1[XS_WATCH_PATH]);
+                if (!state || atoi(state) == 6) {
+                    xs_unwatch(ctx->xsh, l1[0], l1[1]);
+                    xs_rm(ctx->xsh, XBT_NULL, l1[XS_WATCH_TOKEN]);
+                    LIBXL__LOG(ctx, LIBXL__LOG_DEBUG,
+                        "Destroyed device backend at %s",
+                        l1[XS_WATCH_TOKEN]);
+                    rc = 0;
+                }
             }
             free(l1);
         }

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