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From: David Woodhouse <dwmw2@infradead.org>
To: bonzini@redhat.com
Cc: Alex Williamson <alex.williamson@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Jens Axboe <axboe@kernel.dk>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: [PATCH 3/3] kvm/eventfd: Drain events from eventfd in irqfd_wakeup()
Date: Tue, 27 Oct 2020 13:55:23 +0000
Message-ID: <20201027135523.646811-4-dwmw2@infradead.org> (raw)
In-Reply-To: <20201027135523.646811-1-dwmw2@infradead.org>

From: David Woodhouse <dwmw@amazon.co.uk>

Don't allow the events to accumulate in the eventfd counter, drain them
as they are handled.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 virt/kvm/eventfd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index d6408bb497dc..98b5cfa1d69f 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -193,6 +193,9 @@ irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 	int idx;
 
 	if (flags & EPOLLIN) {
+		u64 cnt;
+		eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
+
 		idx = srcu_read_lock(&kvm->irq_srcu);
 		do {
 			seq = read_seqcount_begin(&irqfd->irq_entry_sc);
-- 
2.26.2


  parent reply index

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-26 17:53 [RFC PATCH 1/2] sched/wait: Add add_wait_queue_priority() David Woodhouse
2020-10-26 17:53 ` [RFC PATCH 2/2] kvm/eventfd: Use priority waitqueue to catch events before userspace David Woodhouse
2020-10-27  8:01   ` Paolo Bonzini
2020-10-27 10:15     ` David Woodhouse
2020-10-27 13:55     ` [PATCH 0/3] Allow in-kernel consumers to drain events from eventfd David Woodhouse
2020-10-27 13:55       ` [PATCH 1/3] eventfd: Export eventfd_ctx_do_read() David Woodhouse
2020-10-27 13:55       ` [PATCH 2/3] vfio/virqfd: Drain events from eventfd in virqfd_wakeup() David Woodhouse
2020-11-06 23:29         ` Alex Williamson
2020-11-08  9:17           ` Paolo Bonzini
2020-10-27 13:55       ` David Woodhouse [this message]
2020-10-27 18:41         ` [PATCH 3/3] kvm/eventfd: Drain events from eventfd in irqfd_wakeup() kernel test robot
2020-10-27 21:42         ` kernel test robot
2020-10-27 23:13         ` kernel test robot
2020-10-27 14:39 ` [PATCH v2 0/2] Allow KVM IRQFD to consistently intercept events David Woodhouse
2020-10-27 14:39   ` [PATCH v2 1/2] sched/wait: Add add_wait_queue_priority() David Woodhouse
2020-10-27 19:09     ` Peter Zijlstra
2020-10-27 19:27       ` David Woodhouse
2020-10-27 20:30         ` Peter Zijlstra
2020-10-27 20:49           ` David Woodhouse
2020-10-27 21:32           ` David Woodhouse
2020-10-28 14:20             ` Peter Zijlstra
2020-10-28 14:44               ` Paolo Bonzini
2020-10-28 14:35     ` Peter Zijlstra
2020-11-04  9:35       ` David Woodhouse
2020-11-04 11:25         ` Paolo Bonzini
2020-11-06 10:17         ` Paolo Bonzini
2020-11-06 16:32           ` Alex Williamson
2020-11-06 17:18             ` David Woodhouse
2020-10-27 14:39   ` [PATCH v2 2/2] kvm/eventfd: Use priority waitqueue to catch events before userspace David Woodhouse

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