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Date: Wed, 20 Jul 2016 10:36:45 +0100
From: Stefan Hajnoczi <stefanha@...hat.com>
To: ggarcia@...a.uab.cat
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH] Add timer to handle OOM situations
On Mon, Jul 18, 2016 at 05:11:03PM +0200, ggarcia@...a.uab.cat wrote:
> From: Gerard Garcia <ggarcia@...c.uab.cat>
>
> Better testing support files
>
> Signed-off-by: Gerard Garcia <ggarcia@...c.uab.cat>
> ---
> drivers/vhost/vsock.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 47 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 17bfe4e..d746454 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -14,11 +14,13 @@
> #include <net/sock.h>
> #include <linux/virtio_vsock.h>
> #include <linux/vhost.h>
> +#include <linux/timer.h>
>
> #include <net/af_vsock.h>
> #include "vhost.h"
>
> #define VHOST_VSOCK_DEFAULT_HOST_CID 2
> +#define OOM_RETRY_MS 100
>
> enum {
> VHOST_VSOCK_FEATURES = VHOST_FEATURES,
> @@ -43,8 +45,12 @@ struct vhost_vsock {
> u32 total_tx_buf;
>
> u32 guest_cid;
> +
> + struct timer_list tx_kick;
> };
>
> +
> +
> static u32 vhost_transport_get_local_cid(void)
> {
> return VHOST_VSOCK_DEFAULT_HOST_CID;
> @@ -273,7 +279,8 @@ vhost_transport_send_pkt(struct vsock_sock *vsk,
>
> static struct virtio_vsock_pkt *
> vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
> - unsigned int out, unsigned int in)
> + unsigned int out, unsigned int in,
> + int *error)
You can use <linux/err.h> ERR_PTR(errno) and IS_ERR(ptr)/PTR_ERR()
instead of adding int *error.
> {
> struct virtio_vsock_pkt *pkt;
> struct iov_iter iov_iter;
> @@ -282,12 +289,15 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
>
> if (in != 0) {
> vq_err(vq, "Expected 0 input buffers, got %u\n", in);
> + *error = -EINVAL;
> return NULL;
> }
>
> pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
> - if (!pkt)
> + if (!pkt){
> + *error = -ENOMEM;
> return NULL;
> + }
>
> len = iov_length(vq->iov, out);
> iov_iter_init(&iov_iter, WRITE, vq->iov, out, len);
> @@ -297,6 +307,7 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
> vq_err(vq, "Expected %zu bytes for pkt->hdr, got %zu bytes\n",
> sizeof(pkt->hdr), nbytes);
> kfree(pkt);
> + *error = -EINVAL;
> return NULL;
> }
>
> @@ -310,12 +321,14 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
> /* The pkt is too big */
> if (pkt->len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE) {
> kfree(pkt);
> + *error = -EINVAL;
> return NULL;
> }
>
> pkt->buf = kmalloc(pkt->len, GFP_KERNEL);
> if (!pkt->buf) {
> kfree(pkt);
> + *error = -ENOMEM;
> return NULL;
> }
>
> @@ -324,6 +337,7 @@ vhost_vsock_alloc_pkt(struct vhost_virtqueue *vq,
> vq_err(vq, "Expected %u byte payload, got %zu bytes\n",
> pkt->len, nbytes);
> virtio_transport_free_pkt(pkt);
> + *error = -EINVAL;
> return NULL;
> }
>
> @@ -340,6 +354,7 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
> int head;
> unsigned int out, in;
> bool added = false;
> + int error;
>
> mutex_lock(&vq->mutex);
>
> @@ -361,10 +376,27 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
> break;
> }
>
> - pkt = vhost_vsock_alloc_pkt(vq, out, in);
> + pkt = vhost_vsock_alloc_pkt(vq, out, in, &error);
> +
> if (!pkt) {
> - vq_err(vq, "Faulted on pkt\n");
> - continue;
> + if (error == -ENOMEM) {
> + vhost_discard_vq_desc(vq, 1);
> +
> + if (!timer_pending(&vsock->tx_kick)) {
> + vsock->tx_kick.data =
> + (unsigned long) vq;
> + vsock->tx_kick.expires =
> + jiffies + msecs_to_jiffies(OOM_RETRY_MS);
> + add_timer(&vsock->tx_kick);
> + }
> +
> + break;
> + } else {
> + vq_err(vq, "Faulted on pkt\n");
> + continue;
Please change continue to break (like drivers/vhost/net.c). Let's not
process packets after an invalid one.
> + }
> + } else if (unlikely(timer_pending(&vsock->tx_kick))) {
> + del_timer(&vsock->tx_kick);
> }
>
> /* Only accept correctly addressed packets */
> @@ -383,6 +415,13 @@ out:
> mutex_unlock(&vq->mutex);
> }
>
> +static void vhost_vsock_rehandle_tx_kick(unsigned long data)
> +{
> + struct vhost_virtqueue *vq = (struct vhost_virtqueue *) data;
> +
> + vhost_poll_queue(&vq->poll);
> +}
> +
> static void vhost_vsock_handle_rx_kick(struct vhost_work *work)
> {
> struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
> @@ -493,6 +532,9 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
> goto out;
> }
>
> + setup_timer(&vsock->tx_kick,
> + vhost_vsock_rehandle_tx_kick, (unsigned long) NULL);
> +
Where is the timer deleted when the vhost_vsock instance is released?
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