libxl: fix cleanup of tap devices in libxl__device_destroy

We pass be_path to tapdisk_destroy but we've already deleted it so it
fails to read tapdisk-params. However it appears that we need to
destroy the tap device after tearing down xenstore, to avoid the leak
reported by Greg Wettstein in
<201207312141.q6VLfJje012656@wind.enjellic.com>.

So read the tapdisk-params in the cleanup transaction, before the
remove, and pass that down to destroy_tapdisk instead. tapdisk-params
may of course be NULL if the device isn't a tap device.

There is no need to tear down the tap device from
libxl__initiate_device_remove since this ultimately calls
libxl__device_destroy.

Propagate and log errors from libxl__device_destroy_tapdisk.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 674c88172a..cf5d9e92df 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1344,8 +1344,9 @@ _hidden char *libxl__blktap_devpath(libxl__gc *gc,
 /* libxl__device_destroy_tapdisk:
  *   Destroys any tapdisk process associated with the backend represented
  *   by be_path.
+ *   Always logs on failure.
  */
-_hidden void libxl__device_destroy_tapdisk(libxl__gc *gc, char *be_path);
+_hidden int libxl__device_destroy_tapdisk(libxl__gc *gc, const char *params);
 
 _hidden int libxl__device_from_disk(libxl__gc *gc, uint32_t domid,
                                    libxl_device_disk *disk,