[Xen-devel] [PATCH 13 of 27 v3] libxl: separate forced and non-forced device remove

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1318941402 -3600
# Node ID 16805eff73bdac4758dc84a3507918e5697df30a
# Parent  da6b91661078fcf10247f8aab06a12c2bc2b2eb1
libxl: separate forced and non-forced device remove.

The function libxl__device_destroy currently takes a force parameter however:

  * in the forced case we initiate a graceful shutdown and then immediately
    nuke the backend directory, quite likely before anyone got a chance to 
react.
  * the callers all have a "wait" variable and pass in "!wait" as the force
    argument which is confusing since not waiting is not really the same thing
    as forcing the destroy.

Therefore split the function into libxl__device_remove and
libxl__device_destroy. The former initiates a graceful shutdown which
the latter simply nukes the backend directory.

This makes some of the callers look a bit odd but that should fall out as I
continue to pull this piece of string.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r da6b91661078 -r 16805eff73bd tools/libxl/libxl_device.c
--- a/tools/libxl/libxl_device.c        Tue Oct 18 13:36:42 2011 +0100
+++ b/tools/libxl/libxl_device.c        Tue Oct 18 13:36:42 2011 +0100
@@ -365,7 +365,7 @@ int libxl__device_disk_dev_number(const 
     return -1;
 }
 
-int libxl__device_destroy(libxl__gc *gc, char *be_path, int force)
+int libxl__device_remove(libxl__gc *gc, char *be_path)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
     xs_transaction_t t;
@@ -393,17 +393,22 @@ retry_transaction:
             goto out;
         }
     }
-    if (!force) {
-        xs_watch(ctx->xsh, state_path, be_path);
-        rc = 1;
-    } else {
-        xs_rm(ctx->xsh, XBT_NULL, be_path);
-    }
+
+    xs_watch(ctx->xsh, state_path, be_path);
     libxl__device_destroy_tapdisk(gc, be_path);
+    rc = 1;
 out:
     return rc;
 }
 
+int libxl__device_destroy(libxl__gc *gc, char *be_path)
+{
+    libxl_ctx *ctx = libxl__gc_owner(gc);
+    xs_rm(ctx->xsh, XBT_NULL, be_path);
+    libxl__device_destroy_tapdisk(gc, be_path);
+    return 0;
+}
+
 static int wait_for_dev_destroy(libxl__gc *gc, struct timeval *tv)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
@@ -461,7 +466,9 @@ int libxl__devices_destroy(libxl__gc *gc
             fe_path = libxl__sprintf(gc, "/local/domain/%d/device/%s/%s", 
domid, l1[i], l2[j]);
             be_path = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc, 
"%s/backend", fe_path));
             if (be_path != NULL) {
-                if (libxl__device_destroy(gc, be_path, force) > 0)
+                int rc = force ? libxl__device_destroy(gc, be_path)
+                               : libxl__device_remove(gc, be_path);
+                if (rc > 0)
                     n_watches++;
             } else {
                 xs_rm(ctx->xsh, XBT_NULL, path);
@@ -473,7 +480,9 @@ int libxl__devices_destroy(libxl__gc *gc
     fe_path = libxl__sprintf(gc, "/local/domain/%d/console", domid);
     be_path = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc, "%s/backend", 
fe_path));
     if (be_path && strcmp(be_path, "")) {
-        if (libxl__device_destroy(gc, be_path, force) > 0)
+        int rc = force ? libxl__device_destroy(gc, be_path)
+                       : libxl__device_remove(gc, be_path);
+        if (rc > 0)
             n_watches++;
     }
 
@@ -506,7 +515,10 @@ int libxl__device_del(libxl__gc *gc, lib
 
     backend_path = libxl__device_backend_path(gc, dev);
 
-    rc = libxl__device_destroy(gc, backend_path, !wait);
+    if (wait)
+        rc = libxl__device_remove(gc, backend_path);
+    else
+        rc = libxl__device_destroy(gc, backend_path);
     if (rc == -1) {
         rc = ERROR_FAIL;
         goto out;
diff -r da6b91661078 -r 16805eff73bd tools/libxl/libxl_internal.h
--- a/tools/libxl/libxl_internal.h      Tue Oct 18 13:36:42 2011 +0100
+++ b/tools/libxl/libxl_internal.h      Tue Oct 18 13:36:42 2011 +0100
@@ -253,7 +253,8 @@ _hidden int libxl__device_generic_add(li
 _hidden char *libxl__device_backend_path(libxl__gc *gc, libxl__device *device);
 _hidden char *libxl__device_frontend_path(libxl__gc *gc, libxl__device 
*device);
 _hidden int libxl__device_del(libxl__gc *gc, libxl__device *dev, int wait);
-_hidden int libxl__device_destroy(libxl__gc *gc, char *be_path, int force);
+_hidden int libxl__device_remove(libxl__gc *gc, char *be_path);
+_hidden int libxl__device_destroy(libxl__gc *gc, char *be_path);
 _hidden int libxl__devices_destroy(libxl__gc *gc, uint32_t domid, int force);
 _hidden int libxl__wait_for_backend(libxl__gc *gc, char *be_path, char *state);
 
diff -r da6b91661078 -r 16805eff73bd tools/libxl/libxl_pci.c
--- a/tools/libxl/libxl_pci.c   Tue Oct 18 13:36:42 2011 +0100
+++ b/tools/libxl/libxl_pci.c   Tue Oct 18 13:36:42 2011 +0100
@@ -411,8 +411,7 @@ retry_transaction2:
 
     if (num == 1) {
         char *fe_path = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc, 
"%s/frontend", be_path));
-        libxl__device_destroy(gc, be_path, 1);
-        xs_rm(ctx->xsh, XBT_NULL, be_path);
+        libxl__device_destroy(gc, be_path);
         xs_rm(ctx->xsh, XBT_NULL, fe_path);
         return 0;
     }

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