From 48973c6c938737bb900d15dc82b91dfe3586cb0f Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Tue, 28 Apr 2026 13:17:46 -0300 Subject: RDMA/hns: Fix xarray race in hns_roce_create_srq() Sashiko points out that once the srq memory is stored into the xarray by alloc_srqc() it can immediately be looked up by: xa_lock(&srq_table->xa); srq = xa_load(&srq_table->xa, srqn & (hr_dev->caps.num_srqs - 1)); if (srq) refcount_inc(&srq->refcount); xa_unlock(&srq_table->xa); Which will fail refcount debug because the refcount is 0 and then crash: srq->event(srq, event_type); Because event is NULL. Use refcount_inc_not_zero() instead to ensure a partially prepared srq is never retrieved from the event handler and fix the ordering of the initialization so refcount becomes 1 only after it is fully ready. All the initialization must be done before calling free_srqc() since it depends on the completion and refcount. Fixes: 9a4435375cd1 ("IB/hns: Add driver files for hns RoCE driver") Link: https://sashiko.dev/#/patchset/0-v1-e911b76a94d1%2B65d95-rdma_udata_rep_jgg%40nvidia.com?part=3 Link: https://patch.msgid.link/r/13-v1-41f3135e5565+9d2-rdma_ai_fixes1_jgg@nvidia.com Reviewed-by: Junxian Huang Signed-off-by: Jason Gunthorpe --- drivers/infiniband/hw/hns/hns_roce_srq.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/infiniband/hw/hns/hns_roce_srq.c b/drivers/infiniband/hw/hns/hns_roce_srq.c index cb848e8e6bbd..8b94cbdfa54d 100644 --- a/drivers/infiniband/hw/hns/hns_roce_srq.c +++ b/drivers/infiniband/hw/hns/hns_roce_srq.c @@ -16,8 +16,8 @@ void hns_roce_srq_event(struct hns_roce_dev *hr_dev, u32 srqn, int event_type) xa_lock(&srq_table->xa); srq = xa_load(&srq_table->xa, srqn & (hr_dev->caps.num_srqs - 1)); - if (srq) - refcount_inc(&srq->refcount); + if (srq && !refcount_inc_not_zero(&srq->refcount)) + srq = NULL; xa_unlock(&srq_table->xa); if (!srq) { @@ -470,6 +470,10 @@ int hns_roce_create_srq(struct ib_srq *ib_srq, if (ret) goto err_srqn; + srq->event = hns_roce_ib_srq_event; + init_completion(&srq->free); + refcount_set_release(&srq->refcount, 1); + if (udata) { resp.cap_flags = srq->cap_flags; resp.srqn = srq->srqn; @@ -480,10 +484,6 @@ int hns_roce_create_srq(struct ib_srq *ib_srq, } } - srq->event = hns_roce_ib_srq_event; - refcount_set(&srq->refcount, 1); - init_completion(&srq->free); - return 0; err_srqc: -- cgit v1.2.3