| Message ID | 20231016151909.22133-9-dwmw2@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Get Xen PV shim running in qemu | expand |
On 16/10/2023 16:19, David Woodhouse wrote: > From: David Woodhouse <dwmw@amazon.co.uk> > > If xen_backend_device_create() fails to instantiate a device, the XenBus > code will just keep trying over and over again each time the bus is > re-enumerated, as long as the backend appears online and in > XenbusStateInitialising. > > The only thing which prevents the XenBus code from recreating duplicates > of devices which already exist, is the fact that xen_device_realize() > sets the backend state to XenbusStateInitWait. If the attempt to create > the device doesn't get *that* far, that's when it will keep getting > retried. > > My first thought was to handle errors by setting the backend state to > XenbusStateClosed, but that doesn't work for XenConsole which wants to > *ignore* any device of type != "ioemu" completely. > > So, make xen_backend_device_create() *keep* the XenBackendInstance for a > failed device, and provide a new xen_backend_exists() function to allow > xen_bus_type_enumerate() to check whether one already exists before > creating a new one. > > Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> > --- > hw/xen/xen-backend.c | 27 +++++++++++++++++++++------ > hw/xen/xen-bus.c | 3 ++- > include/hw/xen/xen-backend.h | 1 + > 3 files changed, 24 insertions(+), 7 deletions(-) > Reviewed-by: Paul Durrant <paul@xen.org>
diff --git a/hw/xen/xen-backend.c b/hw/xen/xen-backend.c index 5b0fb76eae..b9bf70a9f5 100644 --- a/hw/xen/xen-backend.c +++ b/hw/xen/xen-backend.c @@ -101,6 +101,24 @@ static XenBackendInstance *xen_backend_list_find(XenDevice *xendev) return NULL; } +bool xen_backend_exists(const char *type, const char *name) +{ + const XenBackendImpl *impl = xen_backend_table_lookup(type); + XenBackendInstance *backend; + + if (!impl) { + return false; + } + + QLIST_FOREACH(backend, &backend_list, entry) { + if (backend->impl == impl && !strcmp(backend->name, name)) { + return true; + } + } + + return false; +} + static void xen_backend_list_remove(XenBackendInstance *backend) { QLIST_REMOVE(backend, entry); @@ -122,11 +140,6 @@ void xen_backend_device_create(XenBus *xenbus, const char *type, backend->name = g_strdup(name); impl->create(backend, opts, errp); - if (*errp) { - g_free(backend->name); - g_free(backend); - return; - } backend->impl = impl; xen_backend_list_add(backend); @@ -165,7 +178,9 @@ bool xen_backend_try_device_destroy(XenDevice *xendev, Error **errp) } impl = backend->impl; - impl->destroy(backend, errp); + if (backend->xendev) { + impl->destroy(backend, errp); + } xen_backend_list_remove(backend); g_free(backend->name); diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index cc524ed92c..0da2aa219a 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -209,7 +209,8 @@ static void xen_bus_type_enumerate(XenBus *xenbus, const char *type) NULL, "%u", &online) != 1) online = 0; - if (online && state == XenbusStateInitialising) { + if (online && state == XenbusStateInitialising && + !xen_backend_exists(type, backend[i])) { Error *local_err = NULL; xen_bus_backend_create(xenbus, type, backend[i], backend_path, diff --git a/include/hw/xen/xen-backend.h b/include/hw/xen/xen-backend.h index aac2fd454d..0f01631ae7 100644 --- a/include/hw/xen/xen-backend.h +++ b/include/hw/xen/xen-backend.h @@ -33,6 +33,7 @@ XenDevice *xen_backend_get_device(XenBackendInstance *backend); void xen_backend_register(const XenBackendInfo *info); const char **xen_backend_get_types(unsigned int *nr); +bool xen_backend_exists(const char *type, const char *name); void xen_backend_device_create(XenBus *xenbus, const char *type, const char *name, QDict *opts, Error **errp); bool xen_backend_try_device_destroy(XenDevice *xendev, Error **errp);