linux-kernel - [3.16 stable PATCH 1/2] virtio-rng: fix stuck of hot-unplugging busy device

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Date:	Sat, 11 Oct 2014 06:51:48 +0800
From:	Amos Kong <akong@...hat.com>
To:	stable@...r.kernel.org
Cc:	rusty@...tcorp.com.au, amit.shah@...hat.com,
	gregkh@...uxfoundation.org,
	virtualization@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: [3.16 stable PATCH 1/2] virtio-rng: fix stuck of hot-unplugging busy device

When we try to hot-remove a busy virtio-rng device from QEMU monitor,
the device can't be hot-removed. Because virtio-rng driver hangs at
wait_for_completion_killable().

This patch exits the waiting by completing have_data completion before
unregistering, resets data_avail to avoid the hwrng core use wrong
buffer bytes.

Signed-off-by: Amos Kong <akong@...hat.com>
Reviewed-by: Amit Shah <amit.shah@...hat.com>
Cc: stable@...r.kernel.org
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
(cherry picked from commit 3856e548372513665670ca5db60d9a74b970fe0d)
Signed-off-by: Amos Kong <akong@...hat.com>
---
 drivers/char/hw_random/virtio-rng.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index f1aa13b..b50252c 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -137,6 +137,8 @@ static void remove_common(struct virtio_device *vdev)
 {
 	struct virtrng_info *vi = vdev->priv;
 
+	vi->data_avail = 0;
+	complete(&vi->have_data);
 	vdev->config->reset(vdev);
 	vi->busy = false;
 	if (vi->hwrng_register_done)
-- 
1.9.3

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