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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 07/15] libxl: disallow attaching the same device more than once
Originally the code allowed users to attach the same device more than
once. It just stupidly overwrites xenstore entries. This is bogus as
frontend will be very confused.
Introduce a helper function to check if the device to be written to
xenstore already exists. A new error code is also introduced.
The check and add are within one xs transaction.
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
change in v3:
place check and add within one xs transaction
---
tools/libxl/libxl.c | 70 +++++++++++++++++++++++++++++++++++++-----
tools/libxl/libxl_device.c | 19 ++++++++++++
tools/libxl/libxl_internal.h | 3 ++
tools/libxl/libxl_pci.c | 35 ++++++++++++++++-----
tools/libxl/libxl_types.idl | 1 +
5 files changed, 112 insertions(+), 16 deletions(-)
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 9bb1a90..ad3495a 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1893,6 +1893,7 @@ void libxl__device_vtpm_add(libxl__egc *egc, uint32_t
domid,
flexarray_t *back;
libxl__device *device;
int rc;
+ xs_transaction_t t = XBT_NULL;
rc = libxl__device_vtpm_setdefault(gc, vtpm);
if (rc) goto out;
@@ -1932,10 +1933,30 @@ void libxl__device_vtpm_add(libxl__egc *egc, uint32_t
domid,
flexarray_append(front, "handle");
flexarray_append(front, GCSPRINTF("%d", vtpm->devid));
- 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),
- NULL);
+ for (;;) {
+ rc = libxl__xs_transaction_start(gc, &t);
+ if (rc) goto out;
+
+ rc = libxl__device_exists(gc, t, device);
+ if (rc < 0) goto out;
+ if (rc == 1) { /* already exists in xenstore */
+ LOG(ERROR, "device already exists in xenstore");
+ aodev->action = LIBXL__DEVICE_ACTION_ADD; /* for error message */
+ rc = ERROR_DEVICE_EXISTS;
+ goto out;
+ }
+
+ libxl__device_generic_add(gc, t, device,
+ libxl__xs_kvs_of_flexarray(gc, back,
+ back->count),
+ libxl__xs_kvs_of_flexarray(gc, front,
+ front->count),
+ NULL);
+
+ rc = libxl__xs_transaction_commit(gc, &t);
+ if (!rc) break;
+ if (rc < 0) goto out;
+ }
aodev->dev = device;
aodev->action = LIBXL__DEVICE_ACTION_ADD;
@@ -1943,6 +1964,7 @@ void libxl__device_vtpm_add(libxl__egc *egc, uint32_t
domid,
rc = 0;
out:
+ libxl__xs_transaction_abort(gc, &t);
aodev->rc = rc;
if(rc) aodev->callback(egc, aodev);
return;
@@ -2209,6 +2231,15 @@ static void device_disk_add(libxl__egc *egc, uint32_t
domid,
goto out;
}
+ rc = libxl__device_exists(gc, t, device);
+ if (rc < 0) goto out;
+ if (rc == 1) { /* already exists in xenstore */
+ LOG(ERROR, "device already exists in xenstore");
+ aodev->action = LIBXL__DEVICE_ACTION_ADD; /* for error message */
+ rc = ERROR_DEVICE_EXISTS;
+ goto out;
+ }
+
switch (disk->backend) {
case LIBXL_DISK_BACKEND_PHY:
dev = disk->pdev_path;
@@ -2998,6 +3029,7 @@ void libxl__device_nic_add(libxl__egc *egc, uint32_t
domid,
flexarray_t *back;
libxl__device *device;
int rc;
+ xs_transaction_t t = XBT_NULL;
rc = libxl__device_nic_setdefault(gc, nic, domid);
if (rc) goto out;
@@ -3068,10 +3100,31 @@ void libxl__device_nic_add(libxl__egc *egc, uint32_t
domid,
flexarray_append(front, "mac");
flexarray_append(front, libxl__sprintf(gc,
LIBXL_MAC_FMT, LIBXL_MAC_BYTES(nic->mac)));
- 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),
- NULL);
+
+ for (;;) {
+ rc = libxl__xs_transaction_start(gc, &t);
+ if (rc) goto out;
+
+ rc = libxl__device_exists(gc, t, device);
+ if (rc < 0) goto out;
+ if (rc == 1) { /* already exists in xenstore */
+ LOG(ERROR, "device already exists in xenstore");
+ aodev->action = LIBXL__DEVICE_ACTION_ADD; /* for error message */
+ rc = ERROR_DEVICE_EXISTS;
+ goto out;
+ }
+
+ libxl__device_generic_add(gc, t, device,
+ libxl__xs_kvs_of_flexarray(gc, back,
+ back->count),
+ libxl__xs_kvs_of_flexarray(gc, front,
+ front->count),
+ NULL);
+
+ rc = libxl__xs_transaction_commit(gc, &t);
+ if (!rc) break;
+ if (rc < 0) goto out;
+ }
aodev->dev = device;
aodev->action = LIBXL__DEVICE_ACTION_ADD;
@@ -3079,6 +3132,7 @@ void libxl__device_nic_add(libxl__egc *egc, uint32_t
domid,
rc = 0;
out:
+ libxl__xs_transaction_abort(gc, &t);
aodev->rc = rc;
if (rc) aodev->callback(egc, aodev);
return;
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index f8a2e1b..045212f 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -40,6 +40,25 @@ char *libxl__device_backend_path(libxl__gc *gc,
libxl__device *device)
device->domid, device->devid);
}
+/* Returns 1 if device exists, 0 if not, ERROR_* (<0) on error. */
+int libxl__device_exists(libxl__gc *gc, xs_transaction_t t,
+ libxl__device *device)
+{
+ int rc;
+ char *be_path = libxl__device_backend_path(gc, device);
+ const char *dir;
+
+ be_path = libxl__device_backend_path(gc, device);
+ rc = libxl__xs_read_checked(gc, t, be_path, &dir);
+
+ if (rc)
+ return rc;
+
+ if (dir)
+ return 1;
+ return 0;
+}
+
int libxl__parse_backend_path(libxl__gc *gc,
const char *path,
libxl__device *dev)
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 3b8f74e..fafef5a 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1033,6 +1033,9 @@ _hidden int libxl__device_console_add(libxl__gc *gc,
uint32_t domid,
libxl__device_console *console,
libxl__domain_build_state *state);
+/* Returns 1 if device exists, 0 if not, ERROR_* (<0) on error. */
+_hidden int libxl__device_exists(libxl__gc *gc, xs_transaction_t t,
+ libxl__device *device);
_hidden int libxl__device_generic_add(libxl__gc *gc, xs_transaction_t t,
libxl__device *device, char **bents, char **fents, char **ro_fents);
_hidden char *libxl__device_backend_path(libxl__gc *gc, libxl__device *device);
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index 0500cf3..38a9642 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -124,6 +124,8 @@ static int libxl__device_pci_add_xenstore(libxl__gc *gc,
uint32_t domid, libxl_d
char *num_devs, *be_path;
int num = 0;
xs_transaction_t t;
+ libxl__device *device;
+ int rc;
be_path = libxl__sprintf(gc, "%s/backend/pci/%d/0",
libxl__xs_get_dompath(gc, 0), domid);
num_devs = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc, "%s/num_devs",
be_path));
@@ -148,15 +150,32 @@ static int libxl__device_pci_add_xenstore(libxl__gc *gc,
uint32_t domid, libxl_d
if (!starting)
flexarray_append_pair(back, "state", libxl__sprintf(gc, "%d", 7));
-retry_transaction:
- t = xs_transaction_start(ctx->xsh);
- libxl__xs_writev(gc, t, be_path,
- libxl__xs_kvs_of_flexarray(gc, back, back->count));
- if (!xs_transaction_end(ctx->xsh, t, 0))
- if (errno == EAGAIN)
- goto retry_transaction;
+ GCNEW(device);
+ libxl__device_from_pcidev(gc, domid, pcidev, device);
- return 0;
+ for (;;) {
+ rc = libxl__xs_transaction_start(gc, &t);
+ if (rc) goto out;
+
+ rc = libxl__device_exists(gc, t, device);
+ if (rc < 0) goto out;
+ if (rc == 1) {
+ LOG(ERROR, "device already exists in xenstore");
+ rc = ERROR_DEVICE_EXISTS;
+ goto out;
+ }
+
+ libxl__xs_writev(gc, t, be_path,
+ libxl__xs_kvs_of_flexarray(gc, back, back->count));
+
+ rc = libxl__xs_transaction_commit(gc, &t);
+ if (!rc) break;
+ if (rc < 0) goto out;
+ }
+
+out:
+ libxl__xs_transaction_abort(gc, &t);
+ return rc;
}
static int libxl__device_pci_remove_xenstore(libxl__gc *gc, uint32_t domid,
libxl_device_pci *pcidev)
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 1cd635e..f1fcbc3 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -60,6 +60,7 @@ libxl_error = Enumeration("error", [
(-14, "UNKNOWN_CHILD"),
(-15, "LOCK_FAIL"),
(-16, "JSON_CONFIG_EMPTY"),
+ (-17, "DEVICE_EXISTS"),
], value_namespace = "")
libxl_domain_type = Enumeration("domain_type", [
--
1.7.10.4
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