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Re: [Qemu-devel] [PATCH v2 1/4] balloon: Allow nested inhibits
From: |
David Hildenbrand |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/4] balloon: Allow nested inhibits |
Date: |
Tue, 31 Jul 2018 10:25:55 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 |
On 31.07.2018 01:13, Alex Williamson wrote:
> A simple true/false internal state does not allow multiple users. Fix
> this within the existing interface by converting to a counter, so long
> as the counter is elevated, ballooning is inhibited.
>
Not sure if "nested" is really the right term here. It is really
multiple users. anyhow
Reviewed-by: David Hildenbrand <address@hidden>
> Signed-off-by: Alex Williamson <address@hidden>
> ---
> balloon.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/balloon.c b/balloon.c
> index 6bf0a9681377..931987983858 100644
> --- a/balloon.c
> +++ b/balloon.c
> @@ -26,6 +26,7 @@
>
> #include "qemu/osdep.h"
> #include "qemu-common.h"
> +#include "qemu/atomic.h"
> #include "exec/cpu-common.h"
> #include "sysemu/kvm.h"
> #include "sysemu/balloon.h"
> @@ -37,16 +38,22 @@
> static QEMUBalloonEvent *balloon_event_fn;
> static QEMUBalloonStatus *balloon_stat_fn;
> static void *balloon_opaque;
> -static bool balloon_inhibited;
> +static int balloon_inhibit_count;
>
> bool qemu_balloon_is_inhibited(void)
> {
> - return balloon_inhibited;
> + return atomic_read(&balloon_inhibit_count) > 0;
> }
>
> void qemu_balloon_inhibit(bool state)
> {
> - balloon_inhibited = state;
> + if (state) {
> + atomic_inc(&balloon_inhibit_count);
> + } else {
> + atomic_dec(&balloon_inhibit_count);
> + }
> +
> + assert(atomic_read(&balloon_inhibit_count) >= 0);
> }
>
> static bool have_balloon(Error **errp)
>
--
Thanks,
David / dhildenb
- [Qemu-devel] [PATCH v2 0/4] Balloon inhibit enhancements, vfio restriction, Alex Williamson, 2018/07/30
- [Qemu-devel] [PATCH v2 1/4] balloon: Allow nested inhibits, Alex Williamson, 2018/07/30
- Re: [Qemu-devel] [PATCH v2 1/4] balloon: Allow nested inhibits,
David Hildenbrand <=
- [Qemu-devel] [PATCH v2 2/4] kvm: Use inhibit to prevent ballooning without synchronous mmu, Alex Williamson, 2018/07/30
- [Qemu-devel] [PATCH v2 3/4] vfio: Inhibit ballooning based on group attachment to a container, Alex Williamson, 2018/07/30
- [Qemu-devel] [PATCH v2 4/4] vfio/ccw/pci: Allow devices to opt-in for ballooning, Alex Williamson, 2018/07/30
- Re: [Qemu-devel] [PATCH v2 0/4] Balloon inhibit enhancements, vfio restriction, Michael S. Tsirkin, 2018/07/31