On Mon, Sep 28, 2015 at 01:42:10PM +0800, Wengang Wang wrote:
> The changing on tx_outstanding should be protected by spinlock or to be
> atomic operations.
>
> Such log is found in dmesg:
>
> Sep 16 14:20:53 naep11x06 kernel: ib0: queue stopped 1, tx_head 1034733, tx_tail 1034733, tx_outstanding 359 ipoib_sendq_size: 512
> Sep 16 14:21:33 naep11x06 kernel: ib0: transmit timeout: latency 9560 msecs
> Sep 16 14:21:33 naep11x06 kernel: ib0: queue stopped 1, tx_head 1034854, tx_tail 1034854, tx_outstanding 511 ipoib_sendq_size: 512
> Sep 16 14:21:38 naep11x06 kernel: ib0: transmit timeout: latency 14568 msecs
> Sep 16 14:21:38 naep11x06 kernel: ib0: queue stopped 1, tx_head 1034854, tx_tail 1034854, tx_outstanding 511 ipoib_sendq_size: 512
>
> And the send queue of ib0 kept full. When transmit timeout is reported,
> queue is reported as "stopped", but the IPoIB stuff tx_head and tx_tail
> points to same value. I am not able to see such numbers in ipoib_cm_tx
> (for CM) because I have no vmcore. Though I am not quite sure it's caused
> by parallel access of tx_outstanding(send path VS interrup path), we really
> need to serialize the changeing on tx_outstanding.
>
> This patch also make sure the increase of tx_outstanding prior to the
> calling of post_send to avoid the possible decreasing before increasing in
> case the running of increasing is scheduled later than the interrupt
> handler.
>
> Signed-off-by: Wengang Wang <wen.gang.wang@xxxxxxxxxx>
> ---
> drivers/infiniband/ulp/ipoib/ipoib_cm.c | 40 +++++++++++++++++++++++----------
> drivers/infiniband/ulp/ipoib/ipoib_ib.c | 24 ++++++++++++++++++--
> 2 files changed, 50 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_cm.c b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> index c78dc16..044da94 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> +++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> @@ -710,6 +710,7 @@ void ipoib_cm_send(struct net_device *dev, struct sk_buff *skb, struct ipoib_cm_
> struct ipoib_dev_priv *priv = netdev_priv(dev);
> struct ipoib_tx_buf *tx_req;
> int rc;
> + unsigned long flags;
>
> if (unlikely(skb->len > tx->mtu)) {
> ipoib_warn(priv, "packet len %d (> %d) too long to send, dropping\n",
> @@ -742,27 +743,36 @@ void ipoib_cm_send(struct net_device *dev, struct sk_buff *skb, struct ipoib_cm_
> skb_orphan(skb);
> skb_dst_drop(skb);
>
> + spin_lock_irqsave(&priv->lock, flags);
> + if (++priv->tx_outstanding == ipoib_sendq_size) {
> + ipoib_dbg(priv, "TX ring 0x%x full, stopping kernel net queue\n",
> + tx->qp->qp_num);
> + netif_stop_queue(dev);
> + }
> + spin_unlock_irqrestore(&priv->lock, flags);
> + if (netif_queue_stopped(dev)) {
> + rc = ib_req_notify_cq(priv->send_cq,
> + IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
> + if (rc < 0)
> + ipoib_warn(priv, "request notify on send CQ failed\n");
> + else if (rc)
> + ipoib_send_comp_handler(priv->send_cq, dev);
> + }
> +
> rc = post_send(priv, tx, tx->tx_head & (ipoib_sendq_size - 1), tx_req);
> if (unlikely(rc)) {
> ipoib_warn(priv, "post_send failed, error %d\n", rc);
> ++dev->stats.tx_errors;
> + spin_lock_irqsave(&priv->lock, flags);
> + --priv->tx_outstanding;
> + if (netif_queue_stopped(dev))
> + netif_wake_queue(dev);
> + spin_unlock_irqrestore(&priv->lock, flags);
Why are you locking the netif_* calls?
> ipoib_dma_unmap_tx(priv, tx_req);
> dev_kfree_skb_any(skb);
> } else {
> dev->trans_start = jiffies;
> ++tx->tx_head;
> -
> - if (++priv->tx_outstanding == ipoib_sendq_size) {
> - ipoib_dbg(priv, "TX ring 0x%x full, stopping kernel net queue\n",
> - tx->qp->qp_num);
> - netif_stop_queue(dev);
> - rc = ib_req_notify_cq(priv->send_cq,
> - IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
> - if (rc < 0)
> - ipoib_warn(priv, "request notify on send CQ failed\n");
> - else if (rc)
> - ipoib_send_comp_handler(priv->send_cq, dev);
> - }
> }
> }
>
> @@ -796,10 +806,13 @@ void ipoib_cm_handle_tx_wc(struct net_device *dev, struct ib_wc *wc)
> netif_tx_lock(dev);
>
> ++tx->tx_tail;
> +
> + spin_lock_irqsave(&priv->lock, flags);
> if (unlikely(--priv->tx_outstanding == ipoib_sendq_size >> 1) &&
> netif_queue_stopped(dev) &&
> test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
> netif_wake_queue(dev);
> + spin_unlock_irqrestore(&priv->lock, flags);
>
> if (wc->status != IB_WC_SUCCESS &&
> wc->status != IB_WC_WR_FLUSH_ERR) {
> @@ -1169,6 +1182,7 @@ static void ipoib_cm_tx_destroy(struct ipoib_cm_tx *p)
> struct ipoib_dev_priv *priv = netdev_priv(p->dev);
> struct ipoib_tx_buf *tx_req;
> unsigned long begin;
> + unsigned long flags;
>
> ipoib_dbg(priv, "Destroy active connection 0x%x head 0x%x tail 0x%x\n",
> p->qp ? p->qp->qp_num : 0, p->tx_head, p->tx_tail);
> @@ -1198,10 +1212,12 @@ timeout:
> dev_kfree_skb_any(tx_req->skb);
> ++p->tx_tail;
> netif_tx_lock_bh(p->dev);
> + spin_lock_irqsave(&priv->lock, flags);
> if (unlikely(--priv->tx_outstanding == ipoib_sendq_size >> 1) &&
> netif_queue_stopped(p->dev) &&
> test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
> netif_wake_queue(p->dev);
> + spin_unlock_irqrestore(&priv->lock, flags);
> netif_tx_unlock_bh(p->dev);
> }
>
> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> index d266667..7616e3c 100644
> --- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> +++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> @@ -377,6 +377,7 @@ static void ipoib_ib_handle_tx_wc(struct net_device *dev, struct ib_wc *wc)
> struct ipoib_dev_priv *priv = netdev_priv(dev);
> unsigned int wr_id = wc->wr_id;
> struct ipoib_tx_buf *tx_req;
> + unsigned long flags;
>
> ipoib_dbg_data(priv, "send completion: id %d, status: %d\n",
> wr_id, wc->status);
> @@ -397,10 +398,13 @@ static void ipoib_ib_handle_tx_wc(struct net_device *dev, struct ib_wc *wc)
> dev_kfree_skb_any(tx_req->skb);
>
> ++priv->tx_tail;
> +
> + spin_lock_irqsave(&priv->lock, flags);
> if (unlikely(--priv->tx_outstanding == ipoib_sendq_size >> 1) &&
> netif_queue_stopped(dev) &&
> test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
> netif_wake_queue(dev);
> + spin_unlock_irqrestore(&priv->lock, flags);
>
> if (wc->status != IB_WC_SUCCESS &&
> wc->status != IB_WC_WR_FLUSH_ERR) {
> @@ -540,6 +544,7 @@ void ipoib_send(struct net_device *dev, struct sk_buff *skb,
> struct ipoib_tx_buf *tx_req;
> int hlen, rc;
> void *phead;
> + unsigned long flags;
>
> if (skb_is_gso(skb)) {
> hlen = skb_transport_offset(skb) + tcp_hdrlen(skb);
> @@ -587,12 +592,22 @@ void ipoib_send(struct net_device *dev, struct sk_buff *skb,
> else
> priv->tx_wr.send_flags &= ~IB_SEND_IP_CSUM;
>
> + spin_lock_irqsave(&priv->lock, flags);
> if (++priv->tx_outstanding == ipoib_sendq_size) {
> ipoib_dbg(priv, "TX ring full, stopping kernel net queue\n");
> if (ib_req_notify_cq(priv->send_cq, IB_CQ_NEXT_COMP))
> ipoib_warn(priv, "request notify on send CQ failed\n");
> netif_stop_queue(dev);
> }
> + spin_unlock_irqrestore(&priv->lock, flags);
> + if (netif_queue_stopped(dev)) {
> + rc = ib_req_notify_cq(priv->send_cq,
> + IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
> + if (rc < 0)
> + ipoib_warn(priv, "request notify on send CQ failed\n");
> + else if (rc)
> + ipoib_send_comp_handler(priv->send_cq, dev);
> + }
>
> skb_orphan(skb);
> skb_dst_drop(skb);
> @@ -602,11 +617,13 @@ void ipoib_send(struct net_device *dev, struct sk_buff *skb,
> if (unlikely(rc)) {
> ipoib_warn(priv, "post_send failed, error %d\n", rc);
> ++dev->stats.tx_errors;
> + spin_lock_irqsave(&priv->lock, flags);
> --priv->tx_outstanding;
> - ipoib_dma_unmap_tx(priv, tx_req);
> - dev_kfree_skb_any(skb);
> if (netif_queue_stopped(dev))
> netif_wake_queue(dev);
> + spin_unlock_irqrestore(&priv->lock, flags);
> + ipoib_dma_unmap_tx(priv, tx_req);
> + dev_kfree_skb_any(skb);
> } else {
> dev->trans_start = jiffies;
>
> @@ -825,6 +842,7 @@ int ipoib_ib_dev_stop(struct net_device *dev)
> unsigned long begin;
> struct ipoib_tx_buf *tx_req;
> int i;
> + unsigned long flags;
>
> if (test_and_clear_bit(IPOIB_FLAG_INITIALIZED, &priv->flags))
> napi_disable(&priv->napi);
> @@ -857,7 +875,9 @@ int ipoib_ib_dev_stop(struct net_device *dev)
> ipoib_dma_unmap_tx(priv, tx_req);
> dev_kfree_skb_any(tx_req->skb);
> ++priv->tx_tail;
> + spin_lock_irqsave(&priv->lock, flags);
> --priv->tx_outstanding;
> + spin_unlock_irqrestore(&priv->lock, flags);
> }
>
> for (i = 0; i < ipoib_recvq_size; ++i) {
> --
> 2.1.0
>
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