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Subject[PATCH 4.9 02/54] vsock/virtio: stop workers during the .remove()
Date
From: Stefano Garzarella <sgarzare@redhat.com>

[ Upstream commit 17dd1367389cfe7f150790c83247b68e0c19d106 ]

Before to call vdev->config->reset(vdev) we need to be sure that
no one is accessing the device, for this reason, we add new variables
in the struct virtio_vsock to stop the workers during the .remove().

This patch also add few comments before vdev->config->reset(vdev)
and vdev->config->del_vqs(vdev).

Suggested-by: Stefan Hajnoczi <stefanha@redhat.com>
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/vmw_vsock/virtio_transport.c | 46 +++++++++++++++++++++++++++++++-
1 file changed, 45 insertions(+), 1 deletion(-)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 32ad7cfa5fa74..67aba63b5c96d 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -39,6 +39,7 @@ struct virtio_vsock {
* must be accessed with tx_lock held.
*/
struct mutex tx_lock;
+ bool tx_run;

struct work_struct send_pkt_work;
spinlock_t send_pkt_list_lock;
@@ -50,6 +51,7 @@ struct virtio_vsock {
* must be accessed with rx_lock held.
*/
struct mutex rx_lock;
+ bool rx_run;
int rx_buf_nr;
int rx_buf_max_nr;

@@ -57,6 +59,7 @@ struct virtio_vsock {
* vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
*/
struct mutex event_lock;
+ bool event_run;
struct virtio_vsock_event event_list[8];

u32 guest_cid;
@@ -91,6 +94,9 @@ virtio_transport_send_pkt_work(struct work_struct *work)

mutex_lock(&vsock->tx_lock);

+ if (!vsock->tx_run)
+ goto out;
+
vq = vsock->vqs[VSOCK_VQ_TX];

for (;;) {
@@ -147,6 +153,7 @@ virtio_transport_send_pkt_work(struct work_struct *work)
if (added)
virtqueue_kick(vq);

+out:
mutex_unlock(&vsock->tx_lock);

if (restart_rx)
@@ -230,6 +237,10 @@ static void virtio_transport_tx_work(struct work_struct *work)

vq = vsock->vqs[VSOCK_VQ_TX];
mutex_lock(&vsock->tx_lock);
+
+ if (!vsock->tx_run)
+ goto out;
+
do {
struct virtio_vsock_pkt *pkt;
unsigned int len;
@@ -240,6 +251,8 @@ static void virtio_transport_tx_work(struct work_struct *work)
added = true;
}
} while (!virtqueue_enable_cb(vq));
+
+out:
mutex_unlock(&vsock->tx_lock);

if (added)
@@ -268,6 +281,9 @@ static void virtio_transport_rx_work(struct work_struct *work)

mutex_lock(&vsock->rx_lock);

+ if (!vsock->rx_run)
+ goto out;
+
do {
virtqueue_disable_cb(vq);
for (;;) {
@@ -376,6 +392,9 @@ static void virtio_transport_event_work(struct work_struct *work)

mutex_lock(&vsock->event_lock);

+ if (!vsock->event_run)
+ goto out;
+
do {
struct virtio_vsock_event *event;
unsigned int len;
@@ -390,7 +409,7 @@ static void virtio_transport_event_work(struct work_struct *work)
} while (!virtqueue_enable_cb(vq));

virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
-
+out:
mutex_unlock(&vsock->event_lock);
}

@@ -521,12 +540,18 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
INIT_WORK(&vsock->event_work, virtio_transport_event_work);
INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);

+ mutex_lock(&vsock->tx_lock);
+ vsock->tx_run = true;
+ mutex_unlock(&vsock->tx_lock);
+
mutex_lock(&vsock->rx_lock);
virtio_vsock_rx_fill(vsock);
+ vsock->rx_run = true;
mutex_unlock(&vsock->rx_lock);

mutex_lock(&vsock->event_lock);
virtio_vsock_event_fill(vsock);
+ vsock->event_run = true;
mutex_unlock(&vsock->event_lock);

vdev->priv = vsock;
@@ -560,6 +585,24 @@ static void virtio_vsock_remove(struct virtio_device *vdev)
/* Reset all connected sockets when the device disappear */
vsock_for_each_connected_socket(virtio_vsock_reset_sock);

+ /* Stop all work handlers to make sure no one is accessing the device,
+ * so we can safely call vdev->config->reset().
+ */
+ mutex_lock(&vsock->rx_lock);
+ vsock->rx_run = false;
+ mutex_unlock(&vsock->rx_lock);
+
+ mutex_lock(&vsock->tx_lock);
+ vsock->tx_run = false;
+ mutex_unlock(&vsock->tx_lock);
+
+ mutex_lock(&vsock->event_lock);
+ vsock->event_run = false;
+ mutex_unlock(&vsock->event_lock);
+
+ /* Flush all device writes and interrupts, device will not use any
+ * more buffers.
+ */
vdev->config->reset(vdev);

mutex_lock(&vsock->rx_lock);
@@ -581,6 +624,7 @@ static void virtio_vsock_remove(struct virtio_device *vdev)
}
spin_unlock_bh(&vsock->send_pkt_list_lock);

+ /* Delete virtqueues and flush outstanding callbacks if any */
vdev->config->del_vqs(vdev);

mutex_unlock(&the_virtio_vsock_mutex);
--
2.25.1


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