From 7dad6b2e440d810273946b0e7092a8fe043c3b8a Mon Sep 17 00:00:00 2001 From: Bart Van Assche Date: Tue, 21 Oct 2014 18:00:35 +0200 Subject: IB/srp: Fix a race condition triggered by destroying a queue pair At least LID reassignment can trigger a race condition in the SRP initiator driver, namely the receive completion handler trying to post a request on a QP during or after QP destruction and before the CQ's have been destroyed. Avoid this race by modifying a QP into the error state and by waiting until all receive completions have been processed before destroying a QP. Reported-by: Max Gurtuvoy Signed-off-by: Bart Van Assche Reviewed-by: Sagi Grimberg Signed-off-by: Christoph Hellwig --- drivers/infiniband/ulp/srp/ib_srp.c | 59 +++++++++++++++++++++++++++++++------ drivers/infiniband/ulp/srp/ib_srp.h | 2 ++ 2 files changed, 52 insertions(+), 9 deletions(-) diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index aac844a..57b5ff1 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -453,6 +453,41 @@ static struct srp_fr_pool *srp_alloc_fr_pool(struct srp_target_port *target) dev->max_pages_per_mr); } +/** + * srp_destroy_qp() - destroy an RDMA queue pair + * @ch: SRP RDMA channel. + * + * Change a queue pair into the error state and wait until all receive + * completions have been processed before destroying it. This avoids that + * the receive completion handler can access the queue pair while it is + * being destroyed. + */ +static void srp_destroy_qp(struct srp_rdma_ch *ch) +{ + struct srp_target_port *target = ch->target; + static struct ib_qp_attr attr = { .qp_state = IB_QPS_ERR }; + static struct ib_recv_wr wr = { .wr_id = SRP_LAST_WR_ID }; + struct ib_recv_wr *bad_wr; + int ret; + + /* Destroying a QP and reusing ch->done is only safe if not connected */ + WARN_ON_ONCE(target->connected); + + ret = ib_modify_qp(ch->qp, &attr, IB_QP_STATE); + WARN_ONCE(ret, "ib_cm_init_qp_attr() returned %d\n", ret); + if (ret) + goto out; + + init_completion(&ch->done); + ret = ib_post_recv(ch->qp, &wr, &bad_wr); + WARN_ONCE(ret, "ib_post_recv() returned %d\n", ret); + if (ret == 0) + wait_for_completion(&ch->done); + +out: + ib_destroy_qp(ch->qp); +} + static int srp_create_ch_ib(struct srp_rdma_ch *ch) { struct srp_target_port *target = ch->target; @@ -469,8 +504,9 @@ static int srp_create_ch_ib(struct srp_rdma_ch *ch) if (!init_attr) return -ENOMEM; + /* + 1 for SRP_LAST_WR_ID */ recv_cq = ib_create_cq(dev->dev, srp_recv_completion, NULL, ch, - target->queue_size, ch->comp_vector); + target->queue_size + 1, ch->comp_vector); if (IS_ERR(recv_cq)) { ret = PTR_ERR(recv_cq); goto err; @@ -487,7 +523,7 @@ static int srp_create_ch_ib(struct srp_rdma_ch *ch) init_attr->event_handler = srp_qp_event; init_attr->cap.max_send_wr = m * target->queue_size; - init_attr->cap.max_recv_wr = target->queue_size; + init_attr->cap.max_recv_wr = target->queue_size + 1; init_attr->cap.max_recv_sge = 1; init_attr->cap.max_send_sge = 1; init_attr->sq_sig_type = IB_SIGNAL_REQ_WR; @@ -530,7 +566,7 @@ static int srp_create_ch_ib(struct srp_rdma_ch *ch) } if (ch->qp) - ib_destroy_qp(ch->qp); + srp_destroy_qp(ch); if (ch->recv_cq) ib_destroy_cq(ch->recv_cq); if (ch->send_cq) @@ -586,7 +622,7 @@ static void srp_free_ch_ib(struct srp_target_port *target, if (ch->fmr_pool) ib_destroy_fmr_pool(ch->fmr_pool); } - ib_destroy_qp(ch->qp); + srp_destroy_qp(ch); ib_destroy_cq(ch->send_cq); ib_destroy_cq(ch->recv_cq); @@ -1883,8 +1919,15 @@ static void srp_tl_err_work(struct work_struct *work) } static void srp_handle_qp_err(u64 wr_id, enum ib_wc_status wc_status, - bool send_err, struct srp_target_port *target) + bool send_err, struct srp_rdma_ch *ch) { + struct srp_target_port *target = ch->target; + + if (wr_id == SRP_LAST_WR_ID) { + complete(&ch->done); + return; + } + if (target->connected && !target->qp_in_error) { if (wr_id & LOCAL_INV_WR_ID_MASK) { shost_printk(KERN_ERR, target->scsi_host, PFX @@ -1915,8 +1958,7 @@ static void srp_recv_completion(struct ib_cq *cq, void *ch_ptr) if (likely(wc.status == IB_WC_SUCCESS)) { srp_handle_recv(ch, &wc); } else { - srp_handle_qp_err(wc.wr_id, wc.status, false, - ch->target); + srp_handle_qp_err(wc.wr_id, wc.status, false, ch); } } } @@ -1932,8 +1974,7 @@ static void srp_send_completion(struct ib_cq *cq, void *ch_ptr) iu = (struct srp_iu *) (uintptr_t) wc.wr_id; list_add(&iu->list, &ch->free_tx); } else { - srp_handle_qp_err(wc.wr_id, wc.status, true, - ch->target); + srp_handle_qp_err(wc.wr_id, wc.status, true, ch); } } } diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h index ca7c6f0..a611556 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.h +++ b/drivers/infiniband/ulp/srp/ib_srp.h @@ -70,6 +70,8 @@ enum { LOCAL_INV_WR_ID_MASK = 1, FAST_REG_WR_ID_MASK = 2, + + SRP_LAST_WR_ID = 0xfffffffcU, }; enum srp_target_state { -- cgit v1.1