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d="scan'208";a="5488460" From: Paul Durrant To: , Date: Wed, 11 Sep 2019 15:36:16 +0100 Message-ID: <20190911143618.23477-2-paul.durrant@citrix.com> X-Mailer: git-send-email 2.20.1.2.gb21ebb6 In-Reply-To: <20190911143618.23477-1-paul.durrant@citrix.com> References: <20190911143618.23477-1-paul.durrant@citrix.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x X-Received-From: 216.71.145.142 Subject: [Qemu-devel] [PATCH 1/3] xen / notify: introduce a new XenWatchList abstraction X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anthony Perard , Paul Durrant , Stefano Stabellini Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Xenstore watch call-backs are already abstracted away from XenBus using the XenWatch data structure but the associated NotifierList manipulation and file handle registation 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 NotifierListEmpty() 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 --- Cc: Stefano Stabellini Cc: 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(&xenbus->watch_notifiers, &watch->notifier); + notifier_list_add(&watch_list->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); 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d="scan'208";a="5488463" From: Paul Durrant To: , Date: Wed, 11 Sep 2019 15:36:17 +0100 Message-ID: <20190911143618.23477-3-paul.durrant@citrix.com> X-Mailer: git-send-email 2.20.1.2.gb21ebb6 In-Reply-To: <20190911143618.23477-1-paul.durrant@citrix.com> References: <20190911143618.23477-1-paul.durrant@citrix.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x X-Received-From: 216.71.145.142 Subject: [Qemu-devel] [PATCH 2/3] xen: introduce separate XenWatchList for XenDevice objects X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anthony Perard , Paul Durrant , Stefano Stabellini Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" This patch uses the XenWatchList abstraction to add a separate watch list for each device. This is more scalable than walking a single notifier list for all watches and is also necessary to implement a bug-fix in a subsequent patch. Signed-off-by: Paul Durrant Reviewed-by: Anthony PERARD --- Cc: Stefano Stabellini Cc: Anthony Perard --- hw/xen/trace-events | 2 ++ hw/xen/xen-bus.c | 72 ++++++++++++++++++++++++++++++++-------- include/hw/xen/xen-bus.h | 2 ++ 3 files changed, 62 insertions(+), 14 deletions(-) diff --git a/hw/xen/trace-events b/hw/xen/trace-events index ac8d9c20d2..80ce3dafad 100644 --- a/hw/xen/trace-events +++ b/hw/xen/trace-events @@ -29,6 +29,8 @@ xen_device_backend_changed(const char *type, char *name) "type: %s name: %s" xen_device_frontend_state(const char *type, char *name, const char *state) "type: %s name: %s -> %s" xen_device_frontend_changed(const char *type, char *name) "type: %s name: %s" xen_device_unplug(const char *type, char *name) "type: %s name: %s" +xen_device_add_watch(const char *type, char *name, const char *node, const char *key) "type: %s name: %s node: %s key: %s" +xen_device_remove_watch(const char *type, char *name, const char *node, const char *key) "type: %s name: %s node: %s key: %s" # xen-bus-helper.c xs_node_create(const char *node) "%s" diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index 28efaccff2..810a4e2df3 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -235,11 +235,11 @@ static void watch_list_remove(XenWatchList *watch_list, XenWatch *watch, static XenWatch *xen_bus_add_watch(XenBus *xenbus, const char *node, const char *key, XenWatchHandler handler, - void *opaque, Error **errp) + Error **errp) { trace_xen_bus_add_watch(node, key); - return watch_list_add(xenbus->watch_list, node, key, handler, opaque, + return watch_list_add(xenbus->watch_list, node, key, handler, xenbus, errp); } @@ -433,7 +433,7 @@ static void xen_bus_realize(BusState *bus, Error **errp) xenbus->backend_watch = xen_bus_add_watch(xenbus, "", /* domain root node */ - "backend", xen_bus_enumerate, xenbus, &local_err); + "backend", xen_bus_enumerate, &local_err); if (local_err) { /* This need not be treated as a hard error so don't propagate */ error_reportf_err(local_err, @@ -621,6 +621,31 @@ static void xen_device_backend_changed(void *opaque) } } +static XenWatch *xen_device_add_watch(XenDevice *xendev, const char *node, + const char *key, + XenWatchHandler handler, + Error **errp) +{ + const char *type = object_get_typename(OBJECT(xendev)); + + trace_xen_device_add_watch(type, xendev->name, node, key); + + return watch_list_add(xendev->watch_list, node, key, handler, xendev, + errp); +} + +static void xen_device_remove_watch(XenDevice *xendev, XenWatch *watch, + Error **errp) +{ + const char *type = object_get_typename(OBJECT(xendev)); + + trace_xen_device_remove_watch(type, xendev->name, watch->node, + watch->key); + + watch_list_remove(xendev->watch_list, watch, errp); +} + + static void xen_device_backend_create(XenDevice *xendev, Error **errp) { XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev))); @@ -645,9 +670,9 @@ static void xen_device_backend_create(XenDevice *xendev, Error **errp) } xendev->backend_state_watch = - xen_bus_add_watch(xenbus, xendev->backend_path, - "state", xen_device_backend_changed, - xendev, &local_err); + xen_device_add_watch(xendev, xendev->backend_path, + "state", xen_device_backend_changed, + &local_err); if (local_err) { error_propagate_prepend(errp, local_err, "failed to watch backend state: "); @@ -655,9 +680,9 @@ static void xen_device_backend_create(XenDevice *xendev, Error **errp) } xendev->backend_online_watch = - xen_bus_add_watch(xenbus, xendev->backend_path, - "online", xen_device_backend_changed, - xendev, &local_err); + xen_device_add_watch(xendev, xendev->backend_path, + "online", xen_device_backend_changed, + &local_err); if (local_err) { error_propagate_prepend(errp, local_err, "failed to watch backend online: "); @@ -671,12 +696,12 @@ static void xen_device_backend_destroy(XenDevice *xendev) Error *local_err = NULL; if (xendev->backend_online_watch) { - xen_bus_remove_watch(xenbus, xendev->backend_online_watch, NULL); + xen_device_remove_watch(xendev, xendev->backend_online_watch, NULL); xendev->backend_online_watch = NULL; } if (xendev->backend_state_watch) { - xen_bus_remove_watch(xenbus, xendev->backend_state_watch, NULL); + xen_device_remove_watch(xendev, xendev->backend_state_watch, NULL); xendev->backend_state_watch = NULL; } @@ -812,8 +837,8 @@ static void xen_device_frontend_create(XenDevice *xendev, Error **errp) } xendev->frontend_state_watch = - xen_bus_add_watch(xenbus, xendev->frontend_path, "state", - xen_device_frontend_changed, xendev, &local_err); + xen_device_add_watch(xendev, xendev->frontend_path, "state", + xen_device_frontend_changed, &local_err); if (local_err) { error_propagate_prepend(errp, local_err, "failed to watch frontend state: "); @@ -826,7 +851,8 @@ static void xen_device_frontend_destroy(XenDevice *xendev) Error *local_err = NULL; if (xendev->frontend_state_watch) { - xen_bus_remove_watch(xenbus, xendev->frontend_state_watch, NULL); + xen_device_remove_watch(xendev, xendev->frontend_state_watch, + NULL); xendev->frontend_state_watch = NULL; } @@ -1122,6 +1148,16 @@ static void xen_device_unrealize(DeviceState *dev, Error **errp) xendev->xgth = NULL; } + if (xendev->watch_list) { + watch_list_destroy(xendev->watch_list); + xendev->watch_list = NULL; + } + + if (xendev->xsh) { + xs_close(xendev->xsh); + xendev->xsh = NULL; + } + g_free(xendev->name); xendev->name = NULL; } @@ -1164,6 +1200,14 @@ static void xen_device_realize(DeviceState *dev, Error **errp) trace_xen_device_realize(type, xendev->name); + xendev->xsh = xs_open(0); + if (!xendev->xsh) { + error_setg_errno(errp, errno, "failed xs_open"); + goto unrealize; + } + + xendev->watch_list = watch_list_create(xendev->xsh); + xendev->xgth = xengnttab_open(NULL, 0); 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x-conformance=sidf_compatible IronPort-SDR: 3OTi9wDh9RvHxeWOvIZ+kuuiSVACKGsvJuBW87nQbgOKhCBN8w1rfnphQ+EqsfdvoQXgzdLgc6 VzqS81TPCqqr638s9x+LVZ21/MqMNnfQIJg6hcauTE1qRcoBPnStUdcDls89rIziPlHhKf3wtl ppZx8lU67Ekstn1vFbVLk0yEn/kYkiSFlJlz1xlPyKxHEc4vVzOfhwfX6Bb9w7LzeRFTJl8t8a UAp+sCrKt1z+0woBeXjdfA7d5keHJ5rlrNEAnGyUPETpFpkMOLQTVKUgH6mGoLF8esgUmxHsFH 3nU= X-SBRS: 2.7 X-MesageID: 5629854 X-Ironport-Server: esa5.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED X-IronPort-AV: E=Sophos;i="5.64,493,1559534400"; d="scan'208";a="5629854" From: Paul Durrant To: , Date: Wed, 11 Sep 2019 15:36:18 +0100 Message-ID: <20190911143618.23477-4-paul.durrant@citrix.com> X-Mailer: git-send-email 2.20.1.2.gb21ebb6 In-Reply-To: <20190911143618.23477-1-paul.durrant@citrix.com> References: <20190911143618.23477-1-paul.durrant@citrix.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x X-Received-From: 216.71.155.168 Subject: [Qemu-devel] [PATCH 3/3] xen: perform XenDevice clean-up in XenBus watch handler X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anthony Perard , Paul Durrant , Stefano Stabellini Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" Cleaning up offine XenDevice objects directly in xen_device_backend_changed() is dangerous as xen_device_unrealize() will modify the watch list that is being walked. Even the QLIST_FOREACH_SAFE() used in notifier_list_notify() is insufficient as *two* notifiers (for the frontend and backend watches) are removed, thus potentially rendering the 'next' pointer unsafe. The solution is to use the XenBus backend_watch handler to do the clean-up instead, as it is invoked whilst walking a separate watch list. This patch therefore adds a new 'offline_devices' list to XenBus, to which offline devices are added by xen_device_backend_changed(). The XenBus backend_watch registration is also changed to not only invoke xen_bus_enumerate() but also a new xen_bus_cleanup() function, which will walk 'offline_devices' and perform the necessary actions. For safety a an extra 'online' check is also added to xen_bus_type_enumerate() to make sure that no attempt is made to create a new XenDevice object for a backend that is offline. NOTE: This patch also include some cosmetic changes: - substitute the local variable name 'backend_state' in xen_bus_type_enumerate() with 'state', since there is no ambiguity with any other state in that context. - change xen_device_state_is_active() to xen_device_frontend_is_active() (and pass a XenDevice directly) since the state tests contained therein only apply to a frontend. - use 'state' rather then 'xendev->backend_state' in xen_device_backend_changed() to shorten the code. Signed-off-by: Paul Durrant --- Cc: Stefano Stabellini Cc: Anthony Perard --- hw/xen/trace-events | 2 + hw/xen/xen-bus.c | 91 +++++++++++++++++++++++++++++----------- include/hw/xen/xen-bus.h | 2 + 3 files changed, 70 insertions(+), 25 deletions(-) diff --git a/hw/xen/trace-events b/hw/xen/trace-events index 80ce3dafad..e6885bc751 100644 --- a/hw/xen/trace-events +++ b/hw/xen/trace-events @@ -17,8 +17,10 @@ xen_domid_restrict(int err) "err: %u" xen_bus_realize(void) "" xen_bus_unrealize(void) "" xen_bus_enumerate(void) "" +xen_bus_cleanup(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_device_cleanup(const char *type, char *name) "type: %s name: %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" diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index 810a4e2df3..055beb7260 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -340,13 +340,18 @@ static void xen_bus_type_enumerate(XenBus *xenbus, const char *type) for (i = 0; i < n; i++) { char *backend_path = g_strdup_printf("%s/%s", domain_path, backend[i]); - enum xenbus_state backend_state; + enum xenbus_state state; + unsigned int online; if (xs_node_scanf(xenbus->xsh, XBT_NULL, backend_path, "state", - NULL, "%u", &backend_state) != 1) - backend_state = XenbusStateUnknown; + NULL, "%u", &state) != 1) + state = XenbusStateUnknown; - if (backend_state == XenbusStateInitialising) { + if (xs_node_scanf(xenbus->xsh, XBT_NULL, backend_path, "online", + NULL, "%u", &online) != 1) + online = 0; + + if (online && state == XenbusStateInitialising) { Error *local_err = NULL; xen_bus_backend_create(xenbus, type, backend[i], backend_path, @@ -365,9 +370,8 @@ out: g_free(domain_path); } -static void xen_bus_enumerate(void *opaque) +static void xen_bus_enumerate(XenBus *xenbus) { - XenBus *xenbus = opaque; char **type; unsigned int i, n; @@ -385,6 +389,44 @@ static void xen_bus_enumerate(void *opaque) free(type); } +static void xen_bus_device_cleanup(XenDevice *xendev) +{ + const char *type = object_get_typename(OBJECT(xendev)); + Error *local_err = NULL; + + trace_xen_bus_device_cleanup(type, xendev->name); + + g_assert(!xendev->backend_online); + + if (!xen_backend_try_device_destroy(xendev, &local_err)) { + object_unparent(OBJECT(xendev)); + } + + if (local_err) { + error_report_err(local_err); + } +} + +static void xen_bus_cleanup(XenBus *xenbus) +{ + XenDevice *xendev, *next; + + trace_xen_bus_cleanup(); + + QLIST_FOREACH_SAFE(xendev, &xenbus->offline_devices, list, next) { + QLIST_REMOVE(xendev, list); + xen_bus_device_cleanup(xendev); + } +} + +static void xen_bus_backend_changed(void *opaque) +{ + XenBus *xenbus = opaque; + + xen_bus_enumerate(xenbus); + xen_bus_cleanup(xenbus); +} + static void xen_bus_unrealize(BusState *bus, Error **errp) { XenBus *xenbus = XEN_BUS(bus); @@ -433,7 +475,7 @@ static void xen_bus_realize(BusState *bus, Error **errp) xenbus->backend_watch = xen_bus_add_watch(xenbus, "", /* domain root node */ - "backend", xen_bus_enumerate, &local_err); + "backend", xen_bus_backend_changed, &local_err); if (local_err) { /* This need not be treated as a hard error so don't propagate */ error_reportf_err(local_err, @@ -555,9 +597,9 @@ static void xen_device_backend_set_online(XenDevice *xendev, bool online) * Tell from the state whether the frontend is likely alive, * i.e. it will react to a change of state of the backend. */ -static bool xen_device_state_is_active(enum xenbus_state state) +static bool xen_device_frontend_is_active(XenDevice *xendev) { - switch (state) { + switch (xendev->frontend_state) { case XenbusStateInitWait: case XenbusStateInitialised: case XenbusStateConnected: @@ -594,30 +636,29 @@ static void xen_device_backend_changed(void *opaque) * state to Closing, but there is no active frontend then set the * backend state to Closed. */ - if (xendev->backend_state == XenbusStateClosing && - !xen_device_state_is_active(xendev->frontend_state)) { + if (state == XenbusStateClosing && + !xen_device_frontend_is_active(xendev)) { xen_device_backend_set_state(xendev, XenbusStateClosed); } /* * If a backend is still 'online' then we should leave it alone but, - * if a backend is not 'online', then the device should be destroyed - * once the state is Closed. + * if a backend is not 'online', then the device is a candidate + * for destruction. Hence add it to the 'offline' list to be cleaned + * by xen_bus_cleanup(). */ - if (!xendev->backend_online && - (xendev->backend_state == XenbusStateClosed || - xendev->backend_state == XenbusStateInitialising || - xendev->backend_state == XenbusStateInitWait || - xendev->backend_state == XenbusStateUnknown)) { - Error *local_err = NULL; + if (!online && + (state == XenbusStateClosed || state == XenbusStateInitialising || + state == XenbusStateInitWait || state == XenbusStateUnknown)) { + XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev))); - if (!xen_backend_try_device_destroy(xendev, &local_err)) { - object_unparent(OBJECT(xendev)); - } + QLIST_INSERT_HEAD(&xenbus->offline_devices, xendev, list); - if (local_err) { - error_report_err(local_err); - } + /* + * Re-write the state to cause a XenBus backend_watch notification, + * resulting in a call to xen_bus_cleanup(). + */ + xen_device_backend_printf(xendev, "state", "%u", state); } } diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h index 0d198148f6..15d71aff70 100644 --- a/include/hw/xen/xen-bus.h +++ b/include/hw/xen/xen-bus.h @@ -33,6 +33,7 @@ typedef struct XenDevice { xengnttab_handle *xgth; bool feature_grant_copy; QLIST_HEAD(, XenEventChannel) event_channels; + QLIST_ENTRY(XenDevice) list; } XenDevice; typedef char *(*XenDeviceGetName)(XenDevice *xendev, Error **errp); @@ -68,6 +69,7 @@ typedef struct XenBus { struct xs_handle *xsh; XenWatchList *watch_list; XenWatch *backend_watch; + QLIST_HEAD(, XenDevice) offline_devices; } XenBus; typedef struct XenBusClass {