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From 8e0778982e9a71000c6a1d999e0caf5934bebd61 Mon Sep 17 00:00:00 2001
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From: Alex Williamson <alex.williamson@redhat.com>
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Date: Thu, 13 Dec 2018 21:54:44 +0100
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Subject: [PATCH 2/5] balloon: Allow multiple inhibit users
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RH-Author: Alex Williamson <alex.williamson@redhat.com>
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Message-id: <154473808463.22725.5535931320059757090.stgit@gimli.home>
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Patchwork-id: 83494
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O-Subject: [RHEL-7.7 qemu-kvm PATCH 2/5] balloon: Allow multiple inhibit users
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Bugzilla: 1659229
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RH-Acked-by: Peter Xu <peterx@redhat.com>
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RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
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RH-Acked-by: Auger Eric <eric.auger@redhat.com>
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Bugzilla: 1659229
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A simple true/false internal state does not allow multiple users.  Fix
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this within the existing interface by converting to a counter, so long
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as the counter is elevated, ballooning is inhibited.
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Reviewed-by: David Hildenbrand <david@redhat.com>
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Reviewed-by: Peter Xu <peterx@redhat.com>
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Reviewed-by: Cornelia Huck <cohuck@redhat.com>
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Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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(cherry picked from commit 01ccbec7bdf6f89f1b7d46dda05e4c1fd2dd5ade)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 balloon.c | 13 ++++++++++---
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 1 file changed, 10 insertions(+), 3 deletions(-)
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diff --git a/balloon.c b/balloon.c
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index c7a0cf1..6a17096 100644
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--- a/balloon.c
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+++ b/balloon.c
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@@ -25,6 +25,7 @@
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  */
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 #include "monitor/monitor.h"
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+#include "qemu/atomic.h"
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 #include "exec/cpu-common.h"
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 #include "sysemu/kvm.h"
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 #include "sysemu/balloon.h"
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@@ -35,16 +36,22 @@
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 static QEMUBalloonEvent *balloon_event_fn;
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 static QEMUBalloonStatus *balloon_stat_fn;
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 static void *balloon_opaque;
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-static bool balloon_inhibited;
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+static int balloon_inhibit_count;
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 bool qemu_balloon_is_inhibited(void)
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 {
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-    return balloon_inhibited;
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+    return atomic_read(&balloon_inhibit_count) > 0;
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 }
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 void qemu_balloon_inhibit(bool state)
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 {
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-    balloon_inhibited = state;
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+    if (state) {
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+        atomic_inc(&balloon_inhibit_count);
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+    } else {
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+        atomic_dec(&balloon_inhibit_count);
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+    }
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+
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+    assert(atomic_read(&balloon_inhibit_count) >= 0);
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 }
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 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
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-- 
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1.8.3.1
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