Currently the completer tasklet when it sets the retransmit timer or the rnr timer sets the same flag (qp->req.need_retry) so that if either timer fires it will attempt to perform a retry flow on the send queue. This has the effect of responding to an RNR NAK at the first retransmit timer event which might not allow for the requested rnr timeout. This patch adds a new flag (qp->req.wait_for_rnr_timer) which, if set, prevents a retry flow until the rnr nak timer fires. This patch fixes rnr retry errors which can be observed by running the pyverbs test_rdmacm_async_traffic_external_qp multiple times. With this patch applied they do not occur. Link: https://lore.kernel.org/linux-rdma/a8287823-1408-4273-bc22-99a0678db640@xxxxxxxxx/ Link: https://lore.kernel.org/linux-rdma/2bafda9e-2bb6-186d-12a1-179e8f6a2678@xxxxxxxxxx/ Fixes: 8700e3e7c485 ("Soft RoCE (RXE) - The software RoCE driver") Signed-off-by: Bob Pearson <rpearsonhpe@xxxxxxxxx> --- v2 Added comments and changed the name of the new flag to make things more understandable per an email exchange with Tom Talpey. --- drivers/infiniband/sw/rxe/rxe_comp.c | 8 +++++++- drivers/infiniband/sw/rxe/rxe_qp.c | 1 + drivers/infiniband/sw/rxe/rxe_req.c | 15 +++++++++++++-- drivers/infiniband/sw/rxe/rxe_verbs.h | 1 + 4 files changed, 22 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c index badd423966dc..3c77201c01d1 100644 --- a/drivers/infiniband/sw/rxe/rxe_comp.c +++ b/drivers/infiniband/sw/rxe/rxe_comp.c @@ -114,6 +114,8 @@ void retransmit_timer(struct timer_list *t) { struct rxe_qp *qp = from_timer(qp, t, retrans_timer); + pr_debug("%s: fired for qp#%d\n", __func__, qp->elem.index); + if (qp->valid) { qp->comp.timeout = 1; rxe_run_task(&qp->comp.task, 1); @@ -729,11 +731,15 @@ int rxe_completer(void *arg) break; case COMPST_RNR_RETRY: + /* we come here if we received an RNR NAK */ if (qp->comp.rnr_retry > 0) { if (qp->comp.rnr_retry != 7) qp->comp.rnr_retry--; - qp->req.need_retry = 1; + /* don't start a retry flow until the + * rnr timer has fired + */ + qp->req.wait_for_rnr_timer = 1; pr_debug("qp#%d set rnr nak timer\n", qp_num(qp)); mod_timer(&qp->rnr_nak_timer, diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c index fc22ff36fdea..2f6f378a232d 100644 --- a/drivers/infiniband/sw/rxe/rxe_qp.c +++ b/drivers/infiniband/sw/rxe/rxe_qp.c @@ -513,6 +513,7 @@ static void rxe_qp_reset(struct rxe_qp *qp) atomic_set(&qp->ssn, 0); qp->req.opcode = -1; qp->req.need_retry = 0; + qp->req.wait_for_rnr_timer = 0; qp->req.noack_pkts = 0; qp->resp.msn = 0; qp->resp.opcode = -1; diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c index d15165e9319c..aa9066ff5257 100644 --- a/drivers/infiniband/sw/rxe/rxe_req.c +++ b/drivers/infiniband/sw/rxe/rxe_req.c @@ -103,7 +103,11 @@ void rnr_nak_timer(struct timer_list *t) { struct rxe_qp *qp = from_timer(qp, t, rnr_nak_timer); - pr_debug("qp#%d rnr nak timer fired\n", qp_num(qp)); + pr_debug("%s: fired for qp#%d\n", __func__, qp_num(qp)); + + /* request a send queue retry */ + qp->req.need_retry = 1; + qp->req.wait_for_rnr_timer = 0; rxe_run_task(&qp->req.task, 1); } @@ -628,10 +632,17 @@ int rxe_requester(void *arg) qp->req.need_rd_atomic = 0; qp->req.wait_psn = 0; qp->req.need_retry = 0; + qp->req.wait_for_rnr_timer = 0; goto exit; } - if (unlikely(qp->req.need_retry)) { + /* we come here if the retransmot timer has fired + * or if the rnr timer has fired. If the retransmit + * timer fires while we are processing an RNR NAK wait + * until the rnr timer has fired before starting the + * retry flow + */ + if (unlikely(qp->req.need_retry && !qp->req.wait_for_rnr_timer)) { req_retry(qp); qp->req.need_retry = 0; } diff --git a/drivers/infiniband/sw/rxe/rxe_verbs.h b/drivers/infiniband/sw/rxe/rxe_verbs.h index 83b6f80440d8..a6c6f0d786c7 100644 --- a/drivers/infiniband/sw/rxe/rxe_verbs.h +++ b/drivers/infiniband/sw/rxe/rxe_verbs.h @@ -123,6 +123,7 @@ struct rxe_req_info { int need_rd_atomic; int wait_psn; int need_retry; + int wait_for_rnr_timer; int noack_pkts; struct rxe_task task; }; -- 2.34.1
