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Subject[PATCH 5.1 073/138] IB/hfi1: Use aborts to trigger RC throttling
Date
[ Upstream commit 4bb02e9572af1383038d83ad196d7166c515f2ee ]

SDMA and pio flushes will cause a lot of packets to be transmitted
after a link has gone down, using a lot of CPU to retransmit
packets.

Fix for RC QPs by recognizing the flush status and:
- Forcing a timer start
- Putting the QP into a "send one" mode

Fixes: 7724105686e7 ("IB/hfi1: add driver files")
Reviewed-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/infiniband/hw/hfi1/rc.c | 30 ++++++++++++++++++++++++++++++
drivers/infiniband/hw/hfi1/verbs.c | 10 ++++++----
drivers/infiniband/hw/hfi1/verbs.h | 1 +
3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/rc.c b/drivers/infiniband/hw/hfi1/rc.c
index 82f101878e33..24cbac277bf0 100644
--- a/drivers/infiniband/hw/hfi1/rc.c
+++ b/drivers/infiniband/hw/hfi1/rc.c
@@ -1703,6 +1703,36 @@ static void reset_sending_psn(struct rvt_qp *qp, u32 psn)
}
}

+/**
+ * hfi1_rc_verbs_aborted - handle abort status
+ * @qp: the QP
+ * @opah: the opa header
+ *
+ * This code modifies both ACK bit in BTH[2]
+ * and the s_flags to go into send one mode.
+ *
+ * This serves to throttle the send engine to only
+ * send a single packet in the likely case the
+ * a link has gone down.
+ */
+void hfi1_rc_verbs_aborted(struct rvt_qp *qp, struct hfi1_opa_header *opah)
+{
+ struct ib_other_headers *ohdr = hfi1_get_rc_ohdr(opah);
+ u8 opcode = ib_bth_get_opcode(ohdr);
+ u32 psn;
+
+ /* ignore responses */
+ if ((opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
+ opcode <= OP(ATOMIC_ACKNOWLEDGE)) ||
+ opcode == TID_OP(READ_RESP) ||
+ opcode == TID_OP(WRITE_RESP))
+ return;
+
+ psn = ib_bth_get_psn(ohdr) | IB_BTH_REQ_ACK;
+ ohdr->bth[2] = cpu_to_be32(psn);
+ qp->s_flags |= RVT_S_SEND_ONE;
+}
+
/*
* This should be called with the QP s_lock held and interrupts disabled.
*/
diff --git a/drivers/infiniband/hw/hfi1/verbs.c b/drivers/infiniband/hw/hfi1/verbs.c
index ea68eeba3f22..63d62ac7434a 100644
--- a/drivers/infiniband/hw/hfi1/verbs.c
+++ b/drivers/infiniband/hw/hfi1/verbs.c
@@ -638,6 +638,8 @@ static void verbs_sdma_complete(
struct hfi1_opa_header *hdr;

hdr = &tx->phdr.hdr;
+ if (unlikely(status == SDMA_TXREQ_S_ABORTED))
+ hfi1_rc_verbs_aborted(qp, hdr);
hfi1_rc_send_complete(qp, hdr);
}
spin_unlock(&qp->s_lock);
@@ -1095,15 +1097,15 @@ int hfi1_verbs_send_pio(struct rvt_qp *qp, struct hfi1_pkt_state *ps,
&ps->s_txreq->phdr.hdr, ib_is_sc5(sc5));

pio_bail:
+ spin_lock_irqsave(&qp->s_lock, flags);
if (qp->s_wqe) {
- spin_lock_irqsave(&qp->s_lock, flags);
rvt_send_complete(qp, qp->s_wqe, wc_status);
- spin_unlock_irqrestore(&qp->s_lock, flags);
} else if (qp->ibqp.qp_type == IB_QPT_RC) {
- spin_lock_irqsave(&qp->s_lock, flags);
+ if (unlikely(wc_status == IB_WC_GENERAL_ERR))
+ hfi1_rc_verbs_aborted(qp, &ps->s_txreq->phdr.hdr);
hfi1_rc_send_complete(qp, &ps->s_txreq->phdr.hdr);
- spin_unlock_irqrestore(&qp->s_lock, flags);
}
+ spin_unlock_irqrestore(&qp->s_lock, flags);

ret = 0;

diff --git a/drivers/infiniband/hw/hfi1/verbs.h b/drivers/infiniband/hw/hfi1/verbs.h
index 62ace0b2d17a..1714c0f6475d 100644
--- a/drivers/infiniband/hw/hfi1/verbs.h
+++ b/drivers/infiniband/hw/hfi1/verbs.h
@@ -415,6 +415,7 @@ void hfi1_rc_hdrerr(

u8 ah_to_sc(struct ib_device *ibdev, struct rdma_ah_attr *ah_attr);

+void hfi1_rc_verbs_aborted(struct rvt_qp *qp, struct hfi1_opa_header *opah);
void hfi1_rc_send_complete(struct rvt_qp *qp, struct hfi1_opa_header *opah);

void hfi1_ud_rcv(struct hfi1_packet *packet);
--
2.20.1


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