[PATCH v4 3/8] libxl: add a transaction parameter to libxl__device_generic_add

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Add a xs_transaction_t parameter to libxl__device_generic_add, if it is
XBT_NULL, allocate a proper one.

Update all the callers.

Changes in v4:
- libxl__device_generic_add: do not end the transaction is the caller
provided it;
- libxl__device_generic_add: fix success exit path.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
---
 tools/libxl/libxl.c          |   10 +++++-----
 tools/libxl/libxl_device.c   |   17 +++++++++++------
 tools/libxl/libxl_internal.h |    4 ++--
 tools/libxl/libxl_pci.c      |    2 +-
 4 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index e645d2a..85082eb 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1401,7 +1401,7 @@ int libxl_device_disk_add(libxl_ctx *ctx, uint32_t domid, libxl_device_disk *dis
     flexarray_append(front, "device-type");
     flexarray_append(front, disk->is_cdrom ? "cdrom" : "disk");
 
-    libxl__device_generic_add(gc, &device,
+    libxl__device_generic_add(gc, XBT_NULL, &device,
                              libxl__xs_kvs_of_flexarray(gc, back, back->count),
                              libxl__xs_kvs_of_flexarray(gc, front, front->count));
 
@@ -1795,7 +1795,7 @@ int libxl_device_nic_add(libxl_ctx *ctx, uint32_t domid, libxl_device_nic *nic)
     flexarray_append(front, "mac");
     flexarray_append(front, libxl__sprintf(gc,
                                     LIBXL_MAC_FMT, LIBXL_MAC_BYTES(nic->mac)));
-    libxl__device_generic_add(gc, &device,
+    libxl__device_generic_add(gc, XBT_NULL, &device,
                              libxl__xs_kvs_of_flexarray(gc, back, back->count),
                              libxl__xs_kvs_of_flexarray(gc, front, front->count));
 
@@ -2073,7 +2073,7 @@ int libxl__device_console_add(libxl__gc *gc, uint32_t domid,
         flexarray_append(front, LIBXL_XENCONSOLE_PROTOCOL);
     }
 
-    libxl__device_generic_add(gc, &device,
+    libxl__device_generic_add(gc, XBT_NULL, &device,
                              libxl__xs_kvs_of_flexarray(gc, back, back->count),
                              libxl__xs_kvs_of_flexarray(gc, front, front->count));
     rc = 0;
@@ -2144,7 +2144,7 @@ int libxl_device_vkb_add(libxl_ctx *ctx, uint32_t domid, libxl_device_vkb *vkb)
     flexarray_append(front, "state");
     flexarray_append(front, libxl__sprintf(gc, "%d", 1));
 
-    libxl__device_generic_add(gc, &device,
+    libxl__device_generic_add(gc, XBT_NULL, &device,
                              libxl__xs_kvs_of_flexarray(gc, back, back->count),
                              libxl__xs_kvs_of_flexarray(gc, front, front->count));
     rc = 0;
@@ -2277,7 +2277,7 @@ int libxl_device_vfb_add(libxl_ctx *ctx, uint32_t domid, libxl_device_vfb *vfb)
                           libxl__sprintf(gc, "%d", vfb->backend_domid));
     flexarray_append_pair(front, "state", libxl__sprintf(gc, "%d", 1));
 
-    libxl__device_generic_add(gc, &device,
+    libxl__device_generic_add(gc, XBT_NULL, &device,
                              libxl__xs_kvs_of_flexarray(gc, back, back->count),
                              libxl__xs_kvs_of_flexarray(gc, front, front->count));
     rc = 0;
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index c7e057d..88cdc7d 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -58,14 +58,14 @@ int libxl__parse_backend_path(libxl__gc *gc,
     return libxl__device_kind_from_string(strkind, &dev->backend_kind);
 }
 
-int libxl__device_generic_add(libxl__gc *gc, libxl__device *device,
-                             char **bents, char **fents)
+int libxl__device_generic_add(libxl__gc *gc, xs_transaction_t t,
+        libxl__device *device, char **bents, char **fents)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
     char *frontend_path, *backend_path;
-    xs_transaction_t t;
     struct xs_permissions frontend_perms[2];
     struct xs_permissions backend_perms[2];
+    int create_transaction = t == XBT_NULL;
 
     frontend_path = libxl__device_frontend_path(gc, device);
     backend_path = libxl__device_backend_path(gc, device);
@@ -81,7 +81,8 @@ int libxl__device_generic_add(libxl__gc *gc, libxl__device *device,
     backend_perms[1].perms = XS_PERM_READ;
 
 retry_transaction:
-    t = xs_transaction_start(ctx->xsh);
+    if (create_transaction)
+        t = xs_transaction_start(ctx->xsh);
     /* FIXME: read frontend_path and check state before removing stuff */
 
     if (fents) {
@@ -100,13 +101,17 @@ retry_transaction:
         libxl__xs_writev(gc, t, backend_path, bents);
     }
 
+    if (!create_transaction)
+        return 0;
+
     if (!xs_transaction_end(ctx->xsh, t, 0)) {
         if (errno == EAGAIN)
             goto retry_transaction;
-        else
+        else {
             LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "xs transaction failed");
+            return ERROR_FAIL;
+        }
     }
-
     return 0;
 }
 
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 2f1cf0f..00856e0 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -681,8 +681,8 @@ _hidden int libxl__device_console_add(libxl__gc *gc, uint32_t domid,
                                       libxl__device_console *console,
                                       libxl__domain_build_state *state);
 
-_hidden int libxl__device_generic_add(libxl__gc *gc, libxl__device *device,
-                             char **bents, char **fents);
+_hidden int libxl__device_generic_add(libxl__gc *gc, xs_transaction_t t,
+        libxl__device *device, char **bents, char **fents);
 _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__parse_backend_path(libxl__gc *gc, const char *path,
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index e8b8839..202a101 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -102,7 +102,7 @@ int libxl__create_pci_backend(libxl__gc *gc, uint32_t domid,
     flexarray_append_pair(front, "backend-id", libxl__sprintf(gc, "%d", 0));
     flexarray_append_pair(front, "state", libxl__sprintf(gc, "%d", 1));
 
-    libxl__device_generic_add(gc, &device,
+    libxl__device_generic_add(gc, XBT_NULL, &device,
                               libxl__xs_kvs_of_flexarray(gc, back, back->count),
                               libxl__xs_kvs_of_flexarray(gc, front, front->count));
 
-- 
1.7.2.5