From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: [PATCH 06/20] notifier: event notifier implementation Date: Thu, 4 Feb 2010 17:27:55 +0200 Message-ID: <20100204152755.GG8461@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: kvm@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:15175 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932221Ab0BDPbG (ORCPT ); Thu, 4 Feb 2010 10:31:06 -0500 Received: from int-mx05.intmail.prod.int.phx2.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.18]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o14FV5ie005278 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 4 Feb 2010 10:31:05 -0500 Received: from redhat.com (vpn2-9-138.ams2.redhat.com [10.36.9.138]) by int-mx05.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id o14FV4ca005127 for ; Thu, 4 Feb 2010 10:31:04 -0500 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: event notifiers are slightly generalized eventfd descriptors. Current implementation depends on eventfd because vhost is the only user, and vhost depends on eventfd anyway, but a stub is provided for non-eventfd case. We'll be able to further generalize this when another user comes along and we see how to best do this. Signed-off-by: Michael S. Tsirkin --- Makefile.target | 1 + hw/notifier.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ hw/notifier.h | 16 ++++++++++++++++ qemu-common.h | 1 + 4 files changed, 68 insertions(+), 0 deletions(-) create mode 100644 hw/notifier.c create mode 100644 hw/notifier.h diff --git a/Makefile.target b/Makefile.target index 0ddd2a0..7df9535 100644 --- a/Makefile.target +++ b/Makefile.target @@ -183,6 +183,7 @@ obj-y = vl.o async.o monitor.o pci.o pci_host.o pcie_host.o machine.o gdbstub.o # virtio has to be here due to weird dependency between PCI and virtio-net. # need to fix this properly obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-pci.o virtio-serial-bus.o +obj-y += notifier.o obj-$(CONFIG_KVM) += kvm.o kvm-all.o # MSI-X depends on kvm for interrupt injection, # so moved it from Makefile.objs to Makefile.target for now diff --git a/hw/notifier.c b/hw/notifier.c new file mode 100644 index 0000000..dff38de --- /dev/null +++ b/hw/notifier.c @@ -0,0 +1,50 @@ +#include "hw.h" +#include "notifier.h" +#ifdef CONFIG_EVENTFD +#include +#endif + +int event_notifier_init(EventNotifier *e, int active) +{ +#ifdef CONFIG_EVENTFD + int fd = eventfd(!!active, EFD_NONBLOCK | EFD_CLOEXEC); + if (fd < 0) + return -errno; + e->fd = fd; + return 0; +#else + return -ENOSYS; +#endif +} + +void event_notifier_cleanup(EventNotifier *e) +{ + close(e->fd); +} + +int event_notifier_get_fd(EventNotifier *e) +{ + return e->fd; +} + +int event_notifier_test_and_clear(EventNotifier *e) +{ + uint64_t value; + int r = read(e->fd, &value, sizeof value); + return r == sizeof value; +} + +int event_notifier_test(EventNotifier *e) +{ + uint64_t value; + int r = read(e->fd, &value, sizeof value); + if (r == sizeof value) { + /* restore previous value. */ + int s = write(e->fd, &value, sizeof value); + /* never blocks because we use EFD_SEMAPHORE. + * If we didn't we'd get EAGAIN on overflow + * and we'd have to write code to ignore it. */ + assert(s == sizeof value); + } + return r == sizeof value; +} diff --git a/hw/notifier.h b/hw/notifier.h new file mode 100644 index 0000000..24117ea --- /dev/null +++ b/hw/notifier.h @@ -0,0 +1,16 @@ +#ifndef QEMU_EVENT_NOTIFIER_H +#define QEMU_EVENT_NOTIFIER_H + +#include "qemu-common.h" + +struct EventNotifier { + int fd; +}; + +int event_notifier_init(EventNotifier *, int active); +void event_notifier_cleanup(EventNotifier *); +int event_notifier_get_fd(EventNotifier *); +int event_notifier_test_and_clear(EventNotifier *); +int event_notifier_test(EventNotifier *); + +#endif diff --git a/qemu-common.h b/qemu-common.h index bf14a22..5e935d1 100644 --- a/qemu-common.h +++ b/qemu-common.h @@ -224,6 +224,7 @@ typedef struct uWireSlave uWireSlave; typedef struct I2SCodec I2SCodec; typedef struct DeviceState DeviceState; typedef struct SSIBus SSIBus; +typedef struct EventNotifier EventNotifier; /* CPU save/load. */ void cpu_save(QEMUFile *f, void *opaque); -- 1.6.6.144.g5c3af