From ff408ba4cd682a3844fd833c0281a68fec6239b3 Mon Sep 17 00:00:00 2001 From: Mike Marciniszyn Date: Mon, 21 Aug 2017 18:26:20 -0700 Subject: [PATCH] IB/{qib, hfi1}: Avoid flow control testing for RDMA write operation commit 5b0ef650bd0f820e922fcc42f1985d4621ae19cf upstream. Section 9.7.7.2.5 of the 1.3 IBTA spec clearly says that receive credits should never apply to RDMA write. qib and hfi1 were doing that. The following situation will result in a QP hang: - A prior SEND or RDMA_WRITE with immmediate consumed the last credit for a QP using RC receive buffer credits - The prior op is acked so there are no more acks - The peer ULP fails to post receive for some reason - An RDMA write sees that the credits are exhausted and waits - The peer ULP posts receive buffers - The ULP posts a send or RDMA write that will be hung The fix is to avoid the credit test for the RDMA write operation. Reviewed-by: Kaike Wan Signed-off-by: Mike Marciniszyn Signed-off-by: Dennis Dalessandro Signed-off-by: Doug Ledford [bwh: Backported to 3.2: - Drop changes to hfi1 - Adjust context] Signed-off-by: Ben Hutchings --- drivers/infiniband/hw/qib/qib_rc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/hw/qib/qib_rc.c b/drivers/infiniband/hw/qib/qib_rc.c index 894afac26f3b..b338dd0fa4d9 100644 --- a/drivers/infiniband/hw/qib/qib_rc.c +++ b/drivers/infiniband/hw/qib/qib_rc.c @@ -365,7 +365,7 @@ int qib_make_rc_req(struct qib_qp *qp) case IB_WR_RDMA_WRITE: if (newreq && !(qp->s_flags & QIB_S_UNLIMITED_CREDIT)) qp->s_lsn++; - /* FALLTHROUGH */ + goto no_flow_control; case IB_WR_RDMA_WRITE_WITH_IMM: /* If no credit, return. */ if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT) && @@ -373,6 +373,7 @@ int qib_make_rc_req(struct qib_qp *qp) qp->s_flags |= QIB_S_WAIT_SSN_CREDIT; goto bail; } +no_flow_control: ohdr->u.rc.reth.vaddr = cpu_to_be64(wqe->wr.wr.rdma.remote_addr); ohdr->u.rc.reth.rkey = -- 2.39.2