From: Sagi Grimberg <[email protected]> In certain scenarios (target kill with live IO) scsi TMFs may race with iser RDMA teardown, which might cause NULL dereference on iser IB device handle (which might have been freed). In this case we take a conditional lock for TMFs and check the connection state (avoid introducing lock contention in the IO path). This is indeed best effort approach, but sufficient to survive multi targets sudden death while heavy IO is inflight.
While we are on it, add a nice kernel-doc style documentation. Reported-by: Ariel Nahum <[email protected]> Signed-off-by: Sagi Grimberg <[email protected]> Signed-off-by: Or Gerlitz <[email protected]> --- drivers/infiniband/ulp/iser/iscsi_iser.c | 49 +++++++++++++++++++++++++----- 1 files changed, 41 insertions(+), 8 deletions(-) diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.c b/drivers/infiniband/ulp/iser/iscsi_iser.c index 0b453e5..0c46f4a 100644 --- a/drivers/infiniband/ulp/iser/iscsi_iser.c +++ b/drivers/infiniband/ulp/iser/iscsi_iser.c @@ -164,18 +164,42 @@ iscsi_iser_pdu_alloc(struct iscsi_task *task, uint8_t opcode) return 0; } -int iser_initialize_task_headers(struct iscsi_task *task, - struct iser_tx_desc *tx_desc) +/** + * iser_initialize_task_headers() - Initialize task headers + * @task: iscsi task + * @tx_desc: iser tx descriptor + * + * Notes: + * This routine may race with iser teardown flow for scsi + * error handling TMFs. So for TMF we should acquire the + * state mutex to avoid dereferencing the IB device which + * may have already been terminated. + */ +int +iser_initialize_task_headers(struct iscsi_task *task, + struct iser_tx_desc *tx_desc) { - struct iser_conn *iser_conn = task->conn->dd_data; + struct iser_conn *iser_conn = task->conn->dd_data; struct iser_device *device = iser_conn->ib_conn.device; struct iscsi_iser_task *iser_task = task->dd_data; u64 dma_addr; + const bool mgmt_task = !task->sc && !in_interrupt(); + int ret = 0; + + if (unlikely(mgmt_task)) + mutex_lock(&iser_conn->state_mutex); + + if (unlikely(iser_conn->state != ISER_CONN_UP)) { + ret = -ENODEV; + goto out; + } dma_addr = ib_dma_map_single(device->ib_device, (void *)tx_desc, ISER_HEADERS_LEN, DMA_TO_DEVICE); - if (ib_dma_mapping_error(device->ib_device, dma_addr)) - return -ENOMEM; + if (ib_dma_mapping_error(device->ib_device, dma_addr)) { + ret = -ENOMEM; + goto out; + } tx_desc->dma_addr = dma_addr; tx_desc->tx_sg[0].addr = tx_desc->dma_addr; @@ -183,7 +207,11 @@ int iser_initialize_task_headers(struct iscsi_task *task, tx_desc->tx_sg[0].lkey = device->mr->lkey; iser_task->iser_conn = iser_conn; - return 0; +out: + if (unlikely(mgmt_task)) + mutex_unlock(&iser_conn->state_mutex); + + return ret; } /** @@ -199,9 +227,14 @@ static int iscsi_iser_task_init(struct iscsi_task *task) { struct iscsi_iser_task *iser_task = task->dd_data; + int ret; - if (iser_initialize_task_headers(task, &iser_task->desc)) - return -ENOMEM; + ret = iser_initialize_task_headers(task, &iser_task->desc); + if (ret) { + iser_err("Failed to init task %p, err = %d\n", + iser_task, ret); + return ret; + } /* mgmt task */ if (!task->sc) -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
