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d="scan'208";a="30419947" To: CC: Peter Maydell , Paul Durrant , Anthony PERARD Subject: [PULL 3/4] xen-bus: reduce scope of backend watch Date: Tue, 20 Oct 2020 11:02:38 +0100 Message-ID: <20201020100239.272748-4-anthony.perard@citrix.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201020100239.272748-1-anthony.perard@citrix.com> References: <20201020100239.272748-1-anthony.perard@citrix.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.71.155.144; envelope-from=anthony.perard@citrix.com; helo=esa4.hc3370-68.iphmx.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/20 06:02:54 X-ACL-Warn: Detected OS = FreeBSD 9.x or newer [fuzzy] X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Reply-to: Anthony PERARD From: Anthony PERARD via X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" From: Paul Durrant Currently a single watch on /local/domain/X/backend is registered by each QEMU process running in service domain X (where X is usually 0). The purpose of this watch is to ensure that QEMU is notified when the Xen toolstack creates a new device backend area. Such a backend area is specific to a single frontend area created for a specific guest domain and, since each QEMU process is also created to servi= ce a specfic guest domain, it is unnecessary and inefficient to notify all QEMU processes. Only the QEMU process associated with the same guest domain need receive the notification. This patch re-factors the watch registration code such that notifications are targetted appropriately. Reported-by: Jerome Leseinne Signed-off-by: Paul Durrant Reviewed-by: Anthony PERARD Message-Id: <20201001081500.1026-1-paul@xen.org> Signed-off-by: Anthony PERARD --- hw/xen/xen-backend.c | 11 ++++++++++ hw/xen/xen-bus.c | 40 ++++++++++++++++++++++++++++-------- include/hw/xen/xen-backend.h | 1 + include/hw/xen/xen-bus.h | 3 ++- 4 files changed, 46 insertions(+), 9 deletions(-) diff --git a/hw/xen/xen-backend.c b/hw/xen/xen-backend.c index 10199fb58d10..5b0fb76eaeb3 100644 --- a/hw/xen/xen-backend.c +++ b/hw/xen/xen-backend.c @@ -41,6 +41,12 @@ static void xen_backend_table_add(XenBackendImpl *impl) g_hash_table_insert(xen_backend_table_get(), (void *)impl->type, impl); } =20 +static const char **xen_backend_table_keys(unsigned int *count) +{ + return (const char **)g_hash_table_get_keys_as_array( + xen_backend_table_get(), count); +} + static const XenBackendImpl *xen_backend_table_lookup(const char *type) { return g_hash_table_lookup(xen_backend_table_get(), type); @@ -70,6 +76,11 @@ void xen_backend_register(const XenBackendInfo *info) xen_backend_table_add(impl); } =20 +const char **xen_backend_get_types(unsigned int *count) +{ + return xen_backend_table_keys(count); +} + static QLIST_HEAD(, XenBackendInstance) backend_list; =20 static void xen_backend_list_add(XenBackendInstance *backend) diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index 9ce1c9540b9e..8c588920d9fc 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -430,7 +430,15 @@ static void xen_bus_unrealize(BusState *bus) trace_xen_bus_unrealize(); =20 if (xenbus->backend_watch) { - xen_bus_remove_watch(xenbus, xenbus->backend_watch, NULL); + unsigned int i; + + for (i =3D 0; i < xenbus->backend_types; i++) { + if (xenbus->backend_watch[i]) { + xen_bus_remove_watch(xenbus, xenbus->backend_watch[i], NUL= L); + } + } + + g_free(xenbus->backend_watch); xenbus->backend_watch =3D NULL; } =20 @@ -446,8 +454,11 @@ static void xen_bus_unrealize(BusState *bus) =20 static void xen_bus_realize(BusState *bus, Error **errp) { + char *key =3D g_strdup_printf("%u", xen_domid); XenBus *xenbus =3D XEN_BUS(bus); unsigned int domid; + const char **type; + unsigned int i; Error *local_err =3D NULL; =20 trace_xen_bus_realize(); @@ -469,19 +480,32 @@ static void xen_bus_realize(BusState *bus, Error **er= rp) =20 module_call_init(MODULE_INIT_XEN_BACKEND); =20 - xenbus->backend_watch =3D - xen_bus_add_watch(xenbus, "", /* domain root node */ - "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, - "failed to set up enumeration watch: "); + type =3D xen_backend_get_types(&xenbus->backend_types); + xenbus->backend_watch =3D g_new(XenWatch *, xenbus->backend_types); + + for (i =3D 0; i < xenbus->backend_types; i++) { + char *node =3D g_strdup_printf("backend/%s", type[i]); + + xenbus->backend_watch[i] =3D + xen_bus_add_watch(xenbus, node, key, 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, + "failed to set up '%s' enumeration watch: ", + type[i]); + } + + g_free(node); } =20 + g_free(type); + g_free(key); return; =20 fail: xen_bus_unrealize(bus); + g_free(key); } =20 static void xen_bus_unplug_request(HotplugHandler *hotplug, diff --git a/include/hw/xen/xen-backend.h b/include/hw/xen/xen-backend.h index 010d71263876..aac2fd454d44 100644 --- a/include/hw/xen/xen-backend.h +++ b/include/hw/xen/xen-backend.h @@ -31,6 +31,7 @@ void xen_backend_set_device(XenBackendInstance *backend, XenDevice *xen_backend_get_device(XenBackendInstance *backend); =20 void xen_backend_register(const XenBackendInfo *info); +const char **xen_backend_get_types(unsigned int *nr); =20 void xen_backend_device_create(XenBus *xenbus, const char *type, const char *name, QDict *opts, Error **errp= ); diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h index 3df696136f7b..6bdbf3ff8220 100644 --- a/include/hw/xen/xen-bus.h +++ b/include/hw/xen/xen-bus.h @@ -66,7 +66,8 @@ struct XenBus { domid_t backend_id; struct xs_handle *xsh; XenWatchList *watch_list; - XenWatch *backend_watch; + unsigned int backend_types; + XenWatch **backend_watch; QLIST_HEAD(, XenDevice) inactive_devices; }; =20 --=20 Anthony PERARD