The current flow of the devd helper (in charge of launching hotplug scripts
inside of driver domains) is to wait for the device backend to switch to
state 6 (XenbusStateClosed) and then remove it. This is not correct, since
a domain can reconnect it's PV devices as many times as it wants.
In order to fix this, introduce the following logic: the control domain will
set the "online" backend node to 0 when it wants the driver domain to
disconnect the device, so now the condition applied in devd is that "state"
must be 6 and "online" 0 in order to proceed with the disconnection.
Signed-off-by: Roger Pau Monné <roger....@citrix.com>
Reported-by: Alex Velazquez <alex.j.velazq...@gmail.com>
Cc: Alex Velazquez <alex.j.velazq...@gmail.com>
Cc: Ian Jackson <ian.jack...@eu.citrix.com>
Cc: Ian Campbell <ian.campb...@citrix.com>
Cc: Wei Liu <wei.l...@citrix.com>
---
tools/libxl/libxl.c | 38 ++++++++++++++++++++++++--------------
tools/libxl/libxl_device.c | 11 ++++++-----
2 files changed, 30 insertions(+), 19 deletions(-)
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 10d1909..1d1917e 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -4410,32 +4410,42 @@ static void backend_watch_callback(libxl__egc *egc,
libxl__ev_xswatch *watch,
libxl__ao *nested_ao = libxl__nested_ao_create(ddomain->ao);
STATE_AO_GC(nested_ao);
char *p, *path;
- const char *sstate;
- int state, rc, num_devs;
+ const char *sstate, *sonline;
+ int state, online, rc, num_devs;
libxl__device *dev = NULL;
libxl__ddomain_device *ddev = NULL;
libxl__ddomain_guest *dguest = NULL;
bool free_ao = false;
- /* Check if event_path ends with "state" and truncate it */
- if (strlen(event_path) < strlen("state"))
+ /* Check if event_path ends with "state" or "online" and truncate it. */
+ if (strlen(event_path) < strlen("state") ||
+ strlen(event_path) < strlen("online"))
goto skip;
path = libxl__strdup(gc, event_path);
- p = path + strlen(path) - strlen("state") - 1;
- if (*p != '/')
- goto skip;
- *p = '\0';
- p++;
- if (strcmp(p, "state") != 0)
- goto skip;
+ p = strstr(path, "/state");
+ if (p != NULL) {
+ *p = '\0';
+ } else {
+ p = strstr(path, "/online");
+ if (p == NULL)
+ goto skip;
+ *p = '\0';
+ }
- /* Check if the state is 1 (XenbusStateInitialising) or greater */
- rc = libxl__xs_read_checked(gc, XBT_NULL, event_path, &sstate);
+ /* Fetch the value of the state and online nodes. */
+ rc = libxl__xs_read_checked(gc, XBT_NULL, GCSPRINTF("%s/state", path),
+ &sstate);
if (rc || !sstate)
goto skip;
state = atoi(sstate);
+ rc = libxl__xs_read_checked(gc, XBT_NULL, GCSPRINTF("%s/online", path),
+ &sonline);
+ if (rc || !sonline)
+ goto skip;
+ online = atoi(sonline);
+
dev = libxl__zalloc(NOGC, sizeof(*dev));
rc = libxl__parse_backend_path(gc, path, dev);
if (rc)
@@ -4477,7 +4487,7 @@ static void backend_watch_callback(libxl__egc *egc,
libxl__ev_xswatch *watch,
rc = add_device(egc, nested_ao, dguest, ddev);
if (rc > 0)
free_ao = true;
- } else if (state == XenbusStateClosed) {
+ } else if (state == XenbusStateClosed && online == 0) {
/*
* Removal of an active device, remove it from the list and
* free it's data structures if they are no longer needed.
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index bee5ed5..51da10e 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -837,16 +837,17 @@ void libxl__initiate_device_remove(libxl__egc *egc,
goto out;
}
+ rc = libxl__xs_write_checked(gc, t, online_path, "0");
+ if (rc) {
+ LOG(ERROR, "unable to write to xenstore path %s", online_path);
+ goto out;
+ }
+
/*
* Check if device is already in "closed" state, in which case
* it should not be changed.
*/
if (state && atoi(state) != XenbusStateClosed) {
- rc = libxl__xs_write_checked(gc, t, online_path, "0");
- if (rc) {
- LOG(ERROR, "unable to write to xenstore path %s", online_path);
- goto out;
- }
rc = libxl__xs_write_checked(gc, t, state_path, GCSPRINTF("%d",
XenbusStateClosing));
if (rc) {
LOG(ERROR, "unable to write to xenstore path %s", state_path);
--
1.9.5 (Apple Git-50.3)
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