[PATCH 2/3] iw_cxgb4: don't block in destroy_qp awaiting the last deref
From: Steve Wise <hidden>
Date: 2016-07-18 20:44:48
Also in:
linux-nvme
Subsystem:
cxgb4 iwarp rnic driver (iw_cxgb4), infiniband subsystem, the rest · Maintainers:
Potnuri Bharat Teja, Jason Gunthorpe, Leon Romanovsky, Linus Torvalds
Blocking in c4iw_destroy_qp() causes a deadlock when apps destroy a qp or disconnect a cm_id from their cm event handler function. There is no nead to block here anyway, so just replace the refcnt atomic with a kref object and free the memory on the last put. Signed-off-by: Steve Wise <redacted> --- drivers/infiniband/hw/cxgb4/iw_cxgb4.h | 2 +- drivers/infiniband/hw/cxgb4/qp.c | 21 ++++++++++++++------- 2 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
index f6f34a7..0420c21 100644
--- a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
+++ b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h@@ -472,7 +472,7 @@ struct c4iw_qp { struct t4_wq wq; spinlock_t lock; struct mutex mutex; - atomic_t refcnt; + struct kref kref; wait_queue_head_t wait; struct timer_list timer; int sq_sig_all;
diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c
index 0d461f3..770531a3 100644
--- a/drivers/infiniband/hw/cxgb4/qp.c
+++ b/drivers/infiniband/hw/cxgb4/qp.c@@ -683,17 +683,25 @@ static int build_inv_stag(union t4_wr *wqe, struct ib_send_wr *wr, return 0; } +void _free_qp(struct kref *kref) +{ + struct c4iw_qp *qhp; + + qhp = container_of(kref, struct c4iw_qp, kref); + PDBG("%s qhp %p\n", __func__, qhp); + kfree(qhp); +} + void c4iw_qp_add_ref(struct ib_qp *qp) { PDBG("%s ib_qp %p\n", __func__, qp); - atomic_inc(&(to_c4iw_qp(qp)->refcnt)); + kref_get(&to_c4iw_qp(qp)->kref); } void c4iw_qp_rem_ref(struct ib_qp *qp) { PDBG("%s ib_qp %p\n", __func__, qp); - if (atomic_dec_and_test(&(to_c4iw_qp(qp)->refcnt))) - wake_up(&(to_c4iw_qp(qp)->wait)); + kref_put(&to_c4iw_qp(qp)->kref, _free_qp); } static void add_to_fc_list(struct list_head *head, struct list_head *entry)
@@ -1592,8 +1600,6 @@ int c4iw_destroy_qp(struct ib_qp *ib_qp) wait_event(qhp->wait, !qhp->ep); remove_handle(rhp, &rhp->qpidr, qhp->wq.sq.qid); - atomic_dec(&qhp->refcnt); - wait_event(qhp->wait, !atomic_read(&qhp->refcnt)); spin_lock_irq(&rhp->lock); if (!list_empty(&qhp->db_fc_entry))
@@ -1606,8 +1612,9 @@ int c4iw_destroy_qp(struct ib_qp *ib_qp) destroy_qp(&rhp->rdev, &qhp->wq, ucontext ? &ucontext->uctx : &rhp->rdev.uctx); + c4iw_qp_rem_ref(ib_qp); + PDBG("%s ib_qp %p qpid 0x%0x\n", __func__, ib_qp, qhp->wq.sq.qid); - kfree(qhp); return 0; }
@@ -1704,7 +1711,7 @@ struct ib_qp *c4iw_create_qp(struct ib_pd *pd, struct ib_qp_init_attr *attrs, init_completion(&qhp->rq_drained); mutex_init(&qhp->mutex); init_waitqueue_head(&qhp->wait); - atomic_set(&qhp->refcnt, 1); + kref_init(&qhp->kref); ret = insert_handle(rhp, &rhp->qpidr, qhp, qhp->wq.sq.qid); if (ret)
--
2.7.0
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