From: Håkon Bugge Date: Tue, 20 Jun 2017 12:07:50 +0000 (+0200) Subject: IB/mlx4: Fix CM REQ retries in paravirt mode X-Git-Tag: v4.13-rc2~13^2~7 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=4542e3c79a2c5a167cbeb4f4190d5f705d272002;p=linux.git IB/mlx4: Fix CM REQ retries in paravirt mode CM REQs cannot be successfully retried, because a new pv_cm_id is created for each request, without checking if one already exists. By checking if an id exists before creating one, the bug is fixed. This bug can be provoked by running an RDMA CM user-land application, but inserting a five seconds delay before the rdma_accept() call on the passive side. This delay is larger than the default CMA timeout, and triggers a retry from the active side. The retried REQ will use another pv_cm_id (the cm_id on the wire). This confuses the CM protocol and two REJs are sent from the passive side. Here is an excerpt from ibdump running without the patch: 3.285092 LID: 4 -> LID: 4 SDP 290 CM: ConnectRequest(SDP Hello) 7.382711 LID: 4 -> LID: 4 SDP 290 CM: ConnectRequest(SDP Hello) 7.382861 LID: 4 -> LID: 4 InfiniBand 290 CM: ConnectReject 7.387644 LID: 4 -> LID: 4 InfiniBand 290 CM: ConnectReject and here is the same with bug fix applied: 3.251010 LID: 4 -> LID: 4 SDP 290 CM: ConnectRequest(SDP Hello) 7.349387 LID: 4 -> LID: 4 SDP 290 CM: ConnectRequest(SDP Hello) 8.258443 LID: 4 -> LID: 4 SDP 290 CM: ConnectReply(SDP Hello) 8.259890 LID: 4 -> LID: 4 InfiniBand 290 CM: ReadyToUse Suggested-by: Venkat Venkatsubra Signed-off-by: Håkon Bugge Reported-by: Wei Lin Guay Tested-by: Wei Lin Guay Reviewed-by: Yuval Shaia Acked-by: Jack Morgenstein Signed-off-by: Doug Ledford --- diff --git a/drivers/infiniband/hw/mlx4/cm.c b/drivers/infiniband/hw/mlx4/cm.c index 1e6c526450d9..fedaf8260105 100644 --- a/drivers/infiniband/hw/mlx4/cm.c +++ b/drivers/infiniband/hw/mlx4/cm.c @@ -323,6 +323,9 @@ int mlx4_ib_multiplex_cm_handler(struct ib_device *ibdev, int port, int slave_id mad->mad_hdr.attr_id == CM_REP_ATTR_ID || mad->mad_hdr.attr_id == CM_SIDR_REQ_ATTR_ID) { sl_cm_id = get_local_comm_id(mad); + id = id_map_get(ibdev, &pv_cm_id, slave_id, sl_cm_id); + if (id) + goto cont; id = id_map_alloc(ibdev, slave_id, sl_cm_id); if (IS_ERR(id)) { mlx4_ib_warn(ibdev, "%s: id{slave: %d, sl_cm_id: 0x%x} Failed to id_map_alloc\n", @@ -343,6 +346,7 @@ int mlx4_ib_multiplex_cm_handler(struct ib_device *ibdev, int port, int slave_id return -EINVAL; } +cont: set_local_comm_id(mad, id->pv_cm_id); if (mad->mad_hdr.attr_id == CM_DREQ_ATTR_ID)