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Subject[PATCH v3 2/3] vsock/virtio: stop workers during the .remove()
Date
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>
---
net/vmw_vsock/virtio_transport.c | 51 +++++++++++++++++++++++++++++++-
1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index 3eaec60aa64f..4dbdce7746bd 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -38,6 +38,7 @@ 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;
@@ -53,6 +54,7 @@ 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;

@@ -60,6 +62,7 @@ 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;
@@ -94,6 +97,10 @@ static void virtio_transport_loopback_work(struct work_struct *work)
spin_unlock_bh(&vsock->loopback_list_lock);

mutex_lock(&vsock->rx_lock);
+
+ if (!vsock->rx_run)
+ goto out;
+
while (!list_empty(&pkts)) {
struct virtio_vsock_pkt *pkt;

@@ -102,6 +109,7 @@ static void virtio_transport_loopback_work(struct work_struct *work)

virtio_transport_recv_pkt(pkt);
}
+out:
mutex_unlock(&vsock->rx_lock);
}

@@ -130,6 +138,9 @@ 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 (;;) {
@@ -188,6 +199,7 @@ virtio_transport_send_pkt_work(struct work_struct *work)
if (added)
virtqueue_kick(vq);

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

if (restart_rx)
@@ -323,6 +335,10 @@ 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;
@@ -333,6 +349,8 @@ 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)
@@ -361,6 +379,9 @@ 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 (;;) {
@@ -470,6 +491,9 @@ 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;
@@ -484,7 +508,7 @@ 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);
}

@@ -620,12 +644,18 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
INIT_WORK(&vsock->loopback_work, virtio_transport_loopback_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;
@@ -660,6 +690,24 @@ 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);
@@ -690,6 +738,7 @@ static void virtio_vsock_remove(struct virtio_device *vdev)
}
spin_unlock_bh(&vsock->loopback_list_lock);

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

mutex_unlock(&the_virtio_vsock_mutex);
--
2.20.1
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