From 374752a26b0ea487dd49c638ee35b97a58ce8e3b Mon Sep 17 00:00:00 2001 From: Paul Durrant Date: Fri, 13 Sep 2019 09:21:56 +0100 Subject: [PATCH] xen / notify: introduce a new XenWatchList abstraction Xenstore watch call-backs are already abstracted away from XenBus using the XenWatch data structure but the associated NotifierList manipulation and file handle registration is still open coded in various xen_bus_...() functions. This patch creates a new XenWatchList data structure to allow these interactions to be abstracted away from XenBus as well. This is in preparation for a subsequent patch which will introduce separate watch lists for XenBus and XenDevice objects. NOTE: This patch also introduces a new notifier_list_empty() helper function for the purposes of adding an assertion that a XenWatchList is not freed whilst its associated NotifierList is still occupied. Signed-off-by: Paul Durrant Reviewed-by: Anthony Perard Message-Id: <20190913082159.31338-2-paul.durrant@citrix.com> Signed-off-by: Anthony PERARD --- hw/xen/trace-events | 5 +- hw/xen/xen-bus.c | 117 +++++++++++++++++++++++++-------------- include/hw/xen/xen-bus.h | 3 +- include/qemu/notify.h | 2 + util/notify.c | 5 ++ 5 files changed, 87 insertions(+), 45 deletions(-) diff --git a/hw/xen/trace-events b/hw/xen/trace-events index bc82ecb1a5..ac8d9c20d2 100644 --- a/hw/xen/trace-events +++ b/hw/xen/trace-events @@ -19,9 +19,8 @@ xen_bus_unrealize(void) "" xen_bus_enumerate(void) "" xen_bus_type_enumerate(const char *type) "type: %s" xen_bus_backend_create(const char *type, const char *path) "type: %s path: %s" -xen_bus_add_watch(const char *node, const char *key, char *token) "node: %s key: %s token: %s" -xen_bus_remove_watch(const char *node, const char *key, char *token) "node: %s key: %s token: %s" -xen_bus_watch(const char *token) "token: %s" +xen_bus_add_watch(const char *node, const char *key) "node: %s key: %s" +xen_bus_remove_watch(const char *node, const char *key) "node: %s key: %s" xen_device_realize(const char *type, char *name) "type: %s name: %s" xen_device_unrealize(const char *type, char *name) "type: %s name: %s" xen_device_backend_state(const char *type, char *name, const char *state) "type: %s name: %s -> %s" diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index 025df5e59f..28efaccff2 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -157,18 +157,60 @@ static void free_watch(XenWatch *watch) g_free(watch); } -static XenWatch *xen_bus_add_watch(XenBus *xenbus, const char *node, - const char *key, XenWatchHandler handler, - void *opaque, Error **errp) +struct XenWatchList { + struct xs_handle *xsh; + NotifierList notifiers; +}; + +static void watch_list_event(void *opaque) +{ + XenWatchList *watch_list = opaque; + char **v; + const char *token; + + v = xs_check_watch(watch_list->xsh); + if (!v) { + return; + } + + token = v[XS_WATCH_TOKEN]; + + notifier_list_notify(&watch_list->notifiers, (void *)token); + + free(v); +} + +static XenWatchList *watch_list_create(struct xs_handle *xsh) +{ + XenWatchList *watch_list = g_new0(XenWatchList, 1); + + g_assert(xsh); + + watch_list->xsh = xsh; + notifier_list_init(&watch_list->notifiers); + qemu_set_fd_handler(xs_fileno(watch_list->xsh), watch_list_event, NULL, + watch_list); + + return watch_list; +} + +static void watch_list_destroy(XenWatchList *watch_list) +{ + g_assert(notifier_list_empty(&watch_list->notifiers)); + qemu_set_fd_handler(xs_fileno(watch_list->xsh), NULL, NULL, NULL); + g_free(watch_list); +} + +static XenWatch *watch_list_add(XenWatchList *watch_list, const char *node, + const char *key, XenWatchHandler handler, + void *opaque, Error **errp) { XenWatch *watch = new_watch(node, key, handler, opaque); Error *local_err = NULL; - trace_xen_bus_add_watch(watch->node, watch->key, watch->token); + notifier_list_add(&watch_list->notifiers, &watch->notifier); - notifier_list_add(&xenbus->watch_notifiers, &watch->notifier); - - xs_node_watch(xenbus->xsh, node, key, watch->token, &local_err); + xs_node_watch(watch_list->xsh, node, key, watch->token, &local_err); if (local_err) { error_propagate(errp, local_err); @@ -181,18 +223,34 @@ static XenWatch *xen_bus_add_watch(XenBus *xenbus, const char *node, return watch; } -static void xen_bus_remove_watch(XenBus *xenbus, XenWatch *watch, - Error **errp) +static void watch_list_remove(XenWatchList *watch_list, XenWatch *watch, + Error **errp) { - trace_xen_bus_remove_watch(watch->node, watch->key, watch->token); - - xs_node_unwatch(xenbus->xsh, watch->node, watch->key, watch->token, + xs_node_unwatch(watch_list->xsh, watch->node, watch->key, watch->token, errp); notifier_remove(&watch->notifier); free_watch(watch); } +static XenWatch *xen_bus_add_watch(XenBus *xenbus, const char *node, + const char *key, XenWatchHandler handler, + void *opaque, Error **errp) +{ + trace_xen_bus_add_watch(node, key); + + return watch_list_add(xenbus->watch_list, node, key, handler, opaque, + errp); +} + +static void xen_bus_remove_watch(XenBus *xenbus, XenWatch *watch, + Error **errp) +{ + trace_xen_bus_remove_watch(watch->node, watch->key); + + watch_list_remove(xenbus->watch_list, watch, errp); +} + static void xen_bus_backend_create(XenBus *xenbus, const char *type, const char *name, char *path, Error **errp) @@ -338,35 +396,14 @@ static void xen_bus_unrealize(BusState *bus, Error **errp) xenbus->backend_watch = NULL; } - if (!xenbus->xsh) { - return; + if (xenbus->watch_list) { + watch_list_destroy(xenbus->watch_list); + xenbus->watch_list = NULL; } - qemu_set_fd_handler(xs_fileno(xenbus->xsh), NULL, NULL, NULL); - - xs_close(xenbus->xsh); -} - -static void xen_bus_watch(void *opaque) -{ - XenBus *xenbus = opaque; - char **v; - const char *token; - - g_assert(xenbus->xsh); - - v = xs_check_watch(xenbus->xsh); - if (!v) { - return; + if (xenbus->xsh) { + xs_close(xenbus->xsh); } - - token = v[XS_WATCH_TOKEN]; - - trace_xen_bus_watch(token); - - notifier_list_notify(&xenbus->watch_notifiers, (void *)token); - - free(v); } static void xen_bus_realize(BusState *bus, Error **errp) @@ -390,9 +427,7 @@ static void xen_bus_realize(BusState *bus, Error **errp) xenbus->backend_id = 0; /* Assume lack of node means dom0 */ } - notifier_list_init(&xenbus->watch_notifiers); - qemu_set_fd_handler(xs_fileno(xenbus->xsh), xen_bus_watch, NULL, - xenbus); + xenbus->watch_list = watch_list_create(xenbus->xsh); module_call_init(MODULE_INIT_XEN_BACKEND); diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h index 1c2d9dfdb8..88b84e29bb 100644 --- a/include/hw/xen/xen-bus.h +++ b/include/hw/xen/xen-bus.h @@ -14,6 +14,7 @@ typedef void (*XenWatchHandler)(void *opaque); +typedef struct XenWatchList XenWatchList; typedef struct XenWatch XenWatch; typedef struct XenEventChannel XenEventChannel; @@ -63,7 +64,7 @@ typedef struct XenBus { BusState qbus; domid_t backend_id; struct xs_handle *xsh; - NotifierList watch_notifiers; + XenWatchList *watch_list; XenWatch *backend_watch; } XenBus; diff --git a/include/qemu/notify.h b/include/qemu/notify.h index a3d73e4bc7..bcfa70fb2e 100644 --- a/include/qemu/notify.h +++ b/include/qemu/notify.h @@ -40,6 +40,8 @@ void notifier_remove(Notifier *notifier); void notifier_list_notify(NotifierList *list, void *data); +bool notifier_list_empty(NotifierList *list); + /* Same as Notifier but allows .notify() to return errors */ typedef struct NotifierWithReturn NotifierWithReturn; diff --git a/util/notify.c b/util/notify.c index aee8d93cb0..76bab212ae 100644 --- a/util/notify.c +++ b/util/notify.c @@ -40,6 +40,11 @@ void notifier_list_notify(NotifierList *list, void *data) } } +bool notifier_list_empty(NotifierList *list) +{ + return QLIST_EMPTY(&list->notifiers); +} + void notifier_with_return_list_init(NotifierWithReturnList *list) { QLIST_INIT(&list->notifiers);