From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wengang Wang Subject: Re: [PATCH] IPoIB: serialize changing on tx_outstanding Date: Thu, 8 Oct 2015 12:55:31 +0800 Message-ID: <5615F743.5050404@oracle.com> References: <1443418930-18677-1-git-send-email-wen.gang.wang@oracle.com> <20151008043317.GB1940@leon.nu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20151008043317.GB1940-2ukJVAZIZ/Y@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: leon-2ukJVAZIZ/Y@public.gmane.org Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org Hi Leon, thanks for review. =E5=9C=A8 2015=E5=B9=B410=E6=9C=8808=E6=97=A5 12:33, Leon Romanovsky =E5= =86=99=E9=81=93: > 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 1034= 733, tx_tail 1034733, tx_outstanding 359 ipoib_sendq_size: 512 >> Sep 16 14:21:33 naep11x06 kernel: ib0: transmit timeout: latency 956= 0 msecs >> Sep 16 14:21:33 naep11x06 kernel: ib0: queue stopped 1, tx_head 1034= 854, tx_tail 1034854, tx_outstanding 511 ipoib_sendq_size: 512 >> Sep 16 14:21:38 naep11x06 kernel: ib0: transmit timeout: latency 145= 68 msecs >> Sep 16 14:21:38 naep11x06 kernel: ib0: queue stopped 1, tx_head 1034= 854, tx_tail 1034854, tx_outstanding 511 ipoib_sendq_size: 512 >> >> And the send queue of ib0 kept full. When transmit timeout is report= ed, >> queue is reported as "stopped", but the IPoIB stuff tx_head and tx_t= ail >> 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 c= aused >> 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 th= e >> calling of post_send to avoid the possible decreasing before increas= ing in >> case the running of increasing is scheduled later than the interrupt >> handler. >> >> Signed-off-by: Wengang Wang >> --- >> 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/infin= iband/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, struc= t sk_buff *skb, struct ipoib_cm_ >> struct ipoib_dev_priv *priv =3D netdev_priv(dev); >> struct ipoib_tx_buf *tx_req; >> int rc; >> + unsigned long flags; >> =20 >> if (unlikely(skb->len > tx->mtu)) { >> ipoib_warn(priv, "packet len %d (> %d) too long to send, droppin= g\n", >> @@ -742,27 +743,36 @@ void ipoib_cm_send(struct net_device *dev, str= uct sk_buff *skb, struct ipoib_cm_ >> skb_orphan(skb); >> skb_dst_drop(skb); >> =20 >> + spin_lock_irqsave(&priv->lock, flags); >> + if (++priv->tx_outstanding =3D=3D 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 =3D 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 =3D 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? Yes, I intended to do that. This make the accessing on tx_outstanding= =20 and the reopening of the send queue in the same atomic session which is= =20 the expected behavior. Otherwise, we may have the following problem: #time order thread1(on cpu1) thread2(on cpu2) lock modify/check tx_outstanding unlock lock modify/check tx_outstanding unlock reopen queue stop queue So that we actually want reopen the send queue, but the result is we=20 stopped it. thanks, wengang >> ipoib_dma_unmap_tx(priv, tx_req); >> dev_kfree_skb_any(skb); >> } else { >> dev->trans_start =3D jiffies; >> ++tx->tx_head; >> - >> - if (++priv->tx_outstanding =3D=3D 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 =3D 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); >> - } >> } >> } >> =20 >> @@ -796,10 +806,13 @@ void ipoib_cm_handle_tx_wc(struct net_device *= dev, struct ib_wc *wc) >> netif_tx_lock(dev); >> =20 >> ++tx->tx_tail; >> + >> + spin_lock_irqsave(&priv->lock, flags); >> if (unlikely(--priv->tx_outstanding =3D=3D 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); >> =20 >> if (wc->status !=3D IB_WC_SUCCESS && >> wc->status !=3D IB_WC_WR_FLUSH_ERR) { >> @@ -1169,6 +1182,7 @@ static void ipoib_cm_tx_destroy(struct ipoib_c= m_tx *p) >> struct ipoib_dev_priv *priv =3D netdev_priv(p->dev); >> struct ipoib_tx_buf *tx_req; >> unsigned long begin; >> + unsigned long flags; >> =20 >> 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 =3D=3D 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); >> } >> =20 >> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infin= iband/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_dev= ice *dev, struct ib_wc *wc) >> struct ipoib_dev_priv *priv =3D netdev_priv(dev); >> unsigned int wr_id =3D wc->wr_id; >> struct ipoib_tx_buf *tx_req; >> + unsigned long flags; >> =20 >> 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_d= evice *dev, struct ib_wc *wc) >> dev_kfree_skb_any(tx_req->skb); >> =20 >> ++priv->tx_tail; >> + >> + spin_lock_irqsave(&priv->lock, flags); >> if (unlikely(--priv->tx_outstanding =3D=3D 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); >> =20 >> if (wc->status !=3D IB_WC_SUCCESS && >> wc->status !=3D IB_WC_WR_FLUSH_ERR) { >> @@ -540,6 +544,7 @@ void ipoib_send(struct net_device *dev, struct s= k_buff *skb, >> struct ipoib_tx_buf *tx_req; >> int hlen, rc; >> void *phead; >> + unsigned long flags; >> =20 >> if (skb_is_gso(skb)) { >> hlen =3D 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 &=3D ~IB_SEND_IP_CSUM; >> =20 >> + spin_lock_irqsave(&priv->lock, flags); >> if (++priv->tx_outstanding =3D=3D 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 =3D 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); >> + } >> =20 >> 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 =3D jiffies; >> =20 >> @@ -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; >> =20 >> 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); >> } >> =20 >> for (i =3D 0; i < ipoib_recvq_size; ++i) { >> --=20 >> 2.1.0 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-rdma= " in >> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html