From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NlpLs-0004jI-OW for qemu-devel@nongnu.org; Sun, 28 Feb 2010 15:02:56 -0500 Received: from [199.232.76.173] (port=58343 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NlpLr-0004hm-CJ for qemu-devel@nongnu.org; Sun, 28 Feb 2010 15:02:55 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1NlpLp-0004Jy-7h for qemu-devel@nongnu.org; Sun, 28 Feb 2010 15:02:54 -0500 Received: from mx1.redhat.com ([209.132.183.28]:32587) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NlpLo-0004Je-P7 for qemu-devel@nongnu.org; Sun, 28 Feb 2010 15:02:53 -0500 Date: Sun, 28 Feb 2010 21:59:36 +0200 From: "Michael S. Tsirkin" Message-ID: <20100228195936.GA547@redhat.com> References: <197f962f6aab3d7fae77ad9f69a3d0dc1ffc07d7.1267122331.git.mst@redhat.com> <4B86CDDC.7060604@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B86CDDC.7060604@codemonkey.ws> Subject: [Qemu-devel] Re: [PATCHv2 03/12] notifier: event notifier implementation List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: amit.shah@redhat.com, kraxel@redhat.com, qemu-devel@nongnu.org, quintela@redhat.com On Thu, Feb 25, 2010 at 01:22:04PM -0600, Anthony Liguori wrote: > On 02/25/2010 12:28 PM, Michael S. Tsirkin wrote: >> 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 4c4d397..c1580e9 100644 >> --- a/Makefile.target >> +++ b/Makefile.target >> @@ -173,6 +173,7 @@ 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-y += rwhandler.o >> obj-$(CONFIG_KVM) += kvm.o kvm-all.o >> obj-$(CONFIG_ISA_MMIO) += isa_mmio.o >> 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; >> > > Probably should handle EINTR, no? No, nonblocking eventfd read never returns EINTR. >> +} >> + >> +int event_notifier_test(EventNotifier *e) >> +{ >> + uint64_t value; >> + int r = read(e->fd,&value, sizeof value); >> > > Coding Style is not quite explicit here but we always use 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 @@ >> > > Needs copyright/license. > > Thanks for doing this abstraction, I'm really happy with it over direct > eventfd usage. > > Regards, > > Anthony Liguori > >> +#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 805be1a..f12a8f5 100644 >> --- a/qemu-common.h >> +++ b/qemu-common.h >> @@ -227,6 +227,7 @@ typedef struct uWireSlave uWireSlave; >> typedef struct I2SCodec I2SCodec; >> typedef struct DeviceState DeviceState; >> typedef struct SSIBus SSIBus; >> +typedef struct EventNotifier EventNotifier; >> >> typedef uint64_t pcibus_t; >> >> > >