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Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to rem
From: |
Greg Kurz |
Subject: |
Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call |
Date: |
Wed, 24 Jan 2018 10:34:02 +0100 |
On Wed, 24 Jan 2018 10:14:57 +0100
Paolo Bonzini <address@hidden> wrote:
> On 24/01/2018 10:05, Greg Kurz wrote:
> > On Wed, 24 Jan 2018 09:46:21 +0100
> > Greg Kurz <address@hidden> wrote:
> >
> >> Please note that Peter usually doesn't work on Wednesdays. The master
> >> branch
> >> might remain broken for everyone until tomorrow... :-\
> >>
> >> And I don't think this is the right fix anyway. See below.
> >>
> >> On Wed, 24 Jan 2018 00:44:14 +0200
> >> "Michael S. Tsirkin" <address@hidden> wrote:
> >>
> >>> From: Jose Ricardo Ziviani <address@hidden>
> >>>
> >>> This commit partially reverts the commit 4fe6d78b2e because of issues
> >>> reported in the virtio.
> >>>
> >>> Examples:
> >>>
> >>> $ qemu-system-ppc64 -cpu POWER8 -nographic -vga none -m 4G \
> >>> -M pseries,accel=kvm -netdev type=user,id=net0 \
> >>> -device virtio-net-pci,netdev=net0 -drive file=../disk.qcow2,if=virtio
> >>>
> >>> Populating /vdevice/address@hidden
> >>> Populating /vdevice/address@hidden
> >>> SCSI: Looking for devices
> >>> 8200000000000000 CD-ROM : "QEMU QEMU CD-ROM 2.5+"
> >>> Populating /address@hidden
> >>> 00 0000 (D) : 1af4 1000 virtio [ net ]
> >>> Aborted
> >>>
> >>> $ qemu-system-x86_64 -m 4G -enable-kvm -drive file=util.qcow2,if=virtio
> >>>
> >>> Running QEMU with GTK 2.x is deprecated, and will be removed
> >>> in a future release. Please switch to GTK 3.x instead
> >>> [1] 5282 abort
> >>>
> >>> Reference
> >>> http://lists.nongnu.org/archive/html/qemu-devel/2018-01/msg05457.html
> >>>
> >>> Reported-by: Anton Blanchard <address@hidden>
> >>> Signed-off-by: Jose Ricardo Ziviani <address@hidden>
> >>> Reviewed-by: Daniel Henrique Barboza <address@hidden>
> >>> Tested-by: Daniel Henrique Barboza <address@hidden>
> >>> Reviewed-by: Michael S. Tsirkin <address@hidden>
> >>> Signed-off-by: Michael S. Tsirkin <address@hidden>
> >>> ---
> >>> accel/kvm/kvm-all.c | 4 ----
> >>> 1 file changed, 4 deletions(-)
> >>>
> >>> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> >>> index 071f4f5..f290f48 100644
> >>> --- a/accel/kvm/kvm-all.c
> >>> +++ b/accel/kvm/kvm-all.c
> >>> @@ -812,10 +812,6 @@ static void kvm_mem_ioeventfd_del(MemoryListener
> >>> *listener,
> >>> if (r < 0) {
> >>> abort();
> >>> }
> >>> -
> >>> - if (e->cleanup) {
> >>> - e->cleanup(e);
> >>> - }
> >>
> >> This looks wrong as the cleanup is expected to do things like closing fds:
> >>
> >> static void virtio_bus_cleanup_event_notifier(EventNotifier *notifier)
> >> {
> >> /* Test and clear notifier after disabling event,
> >> * in case poll callback didn't have time to run.
> >> */
> >> virtio_queue_host_notifier_read(notifier);
> >> event_notifier_cleanup(notifier);
> >> }
> >>
> >> void event_notifier_cleanup(EventNotifier *e)
> >> {
> >> if (e->rfd != e->wfd) {
> >> close(e->rfd);
> >> }
> >> close(e->wfd);
> >> e->rfd = -1;
> >> e->wfd = -1;
> >> e->cleanup = NULL;
> >> }
> >>
> >> And indeed, with this patch applied, QEMU leaks eventfds on every machine
> >> reset.
> >>
> >
> > Reverting 4fe6d78b2e entirely isn't even enough and QEMU aborts at the
> > next machine reset. The following commit must be reverted as well:
> >
> > commit 6f0bb230722931d17fb284eee8efd40b9d653822
> > Author: Gal Hammer <address@hidden>
> > Date: Sun Jan 14 12:06:56 2018 +0200
> >
> > virtio: improve virtio devices initialization time
>
> I'm a bit confused by this patch. The basic idea of wrapping with
> transaction_begin/commit is clear (without it you have quadratic
> behavior from removing one ioeventfd at a time), but I don't understand
> why the new ->cleanup member is needed.
>
I don't understand either... the cover letter of the series says:
"The patch wraps all the changes made to the Memory Regions during the
eventfd registrations in a memory regions transaction. I had to add a
cleanup callback function to the EventNotifier struct, so it will be
possible to use a transaction in the shutdown code path as well."
Until this is sorted out, maybe best to revert both commits or even
the full series (ie, f87d72f5c5bf as well), no ?
> Paolo
- [Qemu-devel] [PULL 0/1] virtio: quick fix, Michael S. Tsirkin, 2018/01/23
- [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Michael S. Tsirkin, 2018/01/23
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Greg Kurz, 2018/01/24
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Greg Kurz, 2018/01/24
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Paolo Bonzini, 2018/01/24
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call,
Greg Kurz <=
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Paolo Bonzini, 2018/01/24
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Michael S. Tsirkin, 2018/01/24
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Gal Hammer, 2018/01/28
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Michael S. Tsirkin, 2018/01/28
- Re: [Qemu-devel] [PULL 1/1] kvm-all: Partially reverts 4fe6d78b2e to remove the cleanup call, Gal Hammer, 2018/01/29
Re: [Qemu-devel] [PULL 0/1] virtio: quick fix, Peter Maydell, 2018/01/24