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[Patch net v3] vsock/virtio: fix variables initialization during resuming

Junnan Wu posted 1 patch 10 months, 1 week ago 
net/vmw_vsock/virtio_transport.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
[Patch net v3] vsock/virtio: fix variables initialization during resuming
Posted by Junnan Wu 10 months, 1 week ago 
When executing suspend to ram twice in a row,
the `rx_buf_nr` and `rx_buf_max_nr` increase to three times vq->num_free.
Then after virtqueue_get_buf and `rx_buf_nr` decreased
in function virtio_transport_rx_work,
the condition to fill rx buffer
(rx_buf_nr < rx_buf_max_nr / 2) will never be met.

It is because that `rx_buf_nr` and `rx_buf_max_nr`
are initialized only in virtio_vsock_probe(),
but they should be reset whenever virtqueues are recreated,
like after a suspend/resume.

Move the `rx_buf_nr` and `rx_buf_max_nr` initialization in
virtio_vsock_vqs_init(), so we are sure that they are properly
initialized, every time we initialize the virtqueues, either when we
load the driver or after a suspend/resume.

To prevent erroneous atomic load operations on the `queued_replies`
in the virtio_transport_send_pkt_work() function
which may disrupt the scheduling of vsock->rx_work
when transmitting reply-required socket packets,
this atomic variable must undergo synchronized initialization
alongside the preceding two variables after a suspend/resume.

Fixes: bd50c5dc182b ("vsock/virtio: add support for device suspend/resume")
Link: https://lore.kernel.org/virtualization/20250207052033.2222629-1-junnan01.wu@samsung.com/
Co-developed-by: Ying Gao <ying01.gao@samsung.com>
Signed-off-by: Ying Gao <ying01.gao@samsung.com>
Signed-off-by: Junnan Wu <junnan01.wu@samsung.com>
---
 net/vmw_vsock/virtio_transport.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index b58c3818f284..f0e48e6911fc 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -670,6 +670,13 @@ static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
 	};
 	int ret;
 
+	mutex_lock(&vsock->rx_lock);
+	vsock->rx_buf_nr = 0;
+	vsock->rx_buf_max_nr = 0;
+	mutex_unlock(&vsock->rx_lock);
+
+	atomic_set(&vsock->queued_replies, 0);
+
 	ret = virtio_find_vqs(vdev, VSOCK_VQ_MAX, vsock->vqs, vqs_info, NULL);
 	if (ret < 0)
 		return ret;
@@ -779,9 +786,6 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 
 	vsock->vdev = vdev;
 
-	vsock->rx_buf_nr = 0;
-	vsock->rx_buf_max_nr = 0;
-	atomic_set(&vsock->queued_replies, 0);
 
 	mutex_init(&vsock->tx_lock);
 	mutex_init(&vsock->rx_lock);
-- 
2.34.1
Re: [Patch net v3] vsock/virtio: fix variables initialization during resuming
Posted by Stefano Garzarella 10 months, 1 week ago 
On Fri, Feb 14, 2025 at 09:22:00AM +0800, Junnan Wu wrote:
>When executing suspend to ram twice in a row,
>the `rx_buf_nr` and `rx_buf_max_nr` increase to three times vq->num_free.
>Then after virtqueue_get_buf and `rx_buf_nr` decreased
>in function virtio_transport_rx_work,
>the condition to fill rx buffer
>(rx_buf_nr < rx_buf_max_nr / 2) will never be met.
>
>It is because that `rx_buf_nr` and `rx_buf_max_nr`
>are initialized only in virtio_vsock_probe(),
>but they should be reset whenever virtqueues are recreated,
>like after a suspend/resume.
>
>Move the `rx_buf_nr` and `rx_buf_max_nr` initialization in
>virtio_vsock_vqs_init(), so we are sure that they are properly
>initialized, every time we initialize the virtqueues, either when we
>load the driver or after a suspend/resume.
>
>To prevent erroneous atomic load operations on the `queued_replies`
>in the virtio_transport_send_pkt_work() function
>which may disrupt the scheduling of vsock->rx_work
>when transmitting reply-required socket packets,
>this atomic variable must undergo synchronized initialization
>alongside the preceding two variables after a suspend/resume.
>
>Fixes: bd50c5dc182b ("vsock/virtio: add support for device suspend/resume")
>Link: https://lore.kernel.org/virtualization/20250207052033.2222629-1-junnan01.wu@samsung.com/
>Co-developed-by: Ying Gao <ying01.gao@samsung.com>
>Signed-off-by: Ying Gao <ying01.gao@samsung.com>
>Signed-off-by: Junnan Wu <junnan01.wu@samsung.com>
>---
> net/vmw_vsock/virtio_transport.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Re: [Patch net v3] vsock/virtio: fix variables initialization during resuming
Posted by Michael S. Tsirkin 10 months, 1 week ago 
On Fri, Feb 14, 2025 at 09:22:00AM +0800, Junnan Wu wrote:
> When executing suspend to ram twice in a row,
> the `rx_buf_nr` and `rx_buf_max_nr` increase to three times vq->num_free.
> Then after virtqueue_get_buf and `rx_buf_nr` decreased
> in function virtio_transport_rx_work,
> the condition to fill rx buffer
> (rx_buf_nr < rx_buf_max_nr / 2) will never be met.
> 
> It is because that `rx_buf_nr` and `rx_buf_max_nr`
> are initialized only in virtio_vsock_probe(),
> but they should be reset whenever virtqueues are recreated,
> like after a suspend/resume.
> 
> Move the `rx_buf_nr` and `rx_buf_max_nr` initialization in
> virtio_vsock_vqs_init(), so we are sure that they are properly
> initialized, every time we initialize the virtqueues, either when we
> load the driver or after a suspend/resume.
> 
> To prevent erroneous atomic load operations on the `queued_replies`
> in the virtio_transport_send_pkt_work() function
> which may disrupt the scheduling of vsock->rx_work
> when transmitting reply-required socket packets,
> this atomic variable must undergo synchronized initialization
> alongside the preceding two variables after a suspend/resume.
> 
> Fixes: bd50c5dc182b ("vsock/virtio: add support for device suspend/resume")
> Link: https://lore.kernel.org/virtualization/20250207052033.2222629-1-junnan01.wu@samsung.com/
> Co-developed-by: Ying Gao <ying01.gao@samsung.com>
> Signed-off-by: Ying Gao <ying01.gao@samsung.com>
> Signed-off-by: Junnan Wu <junnan01.wu@samsung.com>


Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  net/vmw_vsock/virtio_transport.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> index b58c3818f284..f0e48e6911fc 100644
> --- a/net/vmw_vsock/virtio_transport.c
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -670,6 +670,13 @@ static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
>  	};
>  	int ret;
>  
> +	mutex_lock(&vsock->rx_lock);
> +	vsock->rx_buf_nr = 0;
> +	vsock->rx_buf_max_nr = 0;
> +	mutex_unlock(&vsock->rx_lock);
> +
> +	atomic_set(&vsock->queued_replies, 0);
> +
>  	ret = virtio_find_vqs(vdev, VSOCK_VQ_MAX, vsock->vqs, vqs_info, NULL);
>  	if (ret < 0)
>  		return ret;
> @@ -779,9 +786,6 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
>  
>  	vsock->vdev = vdev;
>  
> -	vsock->rx_buf_nr = 0;
> -	vsock->rx_buf_max_nr = 0;
> -	atomic_set(&vsock->queued_replies, 0);
>  
>  	mutex_init(&vsock->tx_lock);
>  	mutex_init(&vsock->rx_lock);
> -- 
> 2.34.1
Re: [Patch net v3] vsock/virtio: fix variables initialization during resuming
Posted by Luigi Leonardi 10 months, 1 week ago 
On Fri, Feb 14, 2025 at 09:22:00AM +0800, Junnan Wu wrote:
>When executing suspend to ram twice in a row,
>the `rx_buf_nr` and `rx_buf_max_nr` increase to three times vq->num_free.
>Then after virtqueue_get_buf and `rx_buf_nr` decreased
>in function virtio_transport_rx_work,
>the condition to fill rx buffer
>(rx_buf_nr < rx_buf_max_nr / 2) will never be met.
>
>It is because that `rx_buf_nr` and `rx_buf_max_nr`
>are initialized only in virtio_vsock_probe(),
>but they should be reset whenever virtqueues are recreated,
>like after a suspend/resume.
>
>Move the `rx_buf_nr` and `rx_buf_max_nr` initialization in
>virtio_vsock_vqs_init(), so we are sure that they are properly
>initialized, every time we initialize the virtqueues, either when we
>load the driver or after a suspend/resume.
>
>To prevent erroneous atomic load operations on the `queued_replies`
>in the virtio_transport_send_pkt_work() function
>which may disrupt the scheduling of vsock->rx_work
>when transmitting reply-required socket packets,
>this atomic variable must undergo synchronized initialization
>alongside the preceding two variables after a suspend/resume.
>
>Fixes: bd50c5dc182b ("vsock/virtio: add support for device suspend/resume")
>Link: https://lore.kernel.org/virtualization/20250207052033.2222629-1-junnan01.wu@samsung.com/
>Co-developed-by: Ying Gao <ying01.gao@samsung.com>
>Signed-off-by: Ying Gao <ying01.gao@samsung.com>
>Signed-off-by: Junnan Wu <junnan01.wu@samsung.com>
>---
> net/vmw_vsock/virtio_transport.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
>diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>index b58c3818f284..f0e48e6911fc 100644
>--- a/net/vmw_vsock/virtio_transport.c
>+++ b/net/vmw_vsock/virtio_transport.c
>@@ -670,6 +670,13 @@ static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
> 	};
> 	int ret;
>
>+	mutex_lock(&vsock->rx_lock);
>+	vsock->rx_buf_nr = 0;
>+	vsock->rx_buf_max_nr = 0;
>+	mutex_unlock(&vsock->rx_lock);
>+
>+	atomic_set(&vsock->queued_replies, 0);
>+
> 	ret = virtio_find_vqs(vdev, VSOCK_VQ_MAX, vsock->vqs, vqs_info, NULL);
> 	if (ret < 0)
> 		return ret;
>@@ -779,9 +786,6 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
>
> 	vsock->vdev = vdev;
>
>-	vsock->rx_buf_nr = 0;
>-	vsock->rx_buf_max_nr = 0;
>-	atomic_set(&vsock->queued_replies, 0);
>
> 	mutex_init(&vsock->tx_lock);
> 	mutex_init(&vsock->rx_lock);
>-- 
>2.34.1
>

Reviewed-by: Luigi Leonardi <leonardi@redhat.com>

Patchew 2.1-devel-b67e4c2

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