iw_cxgb4: don't block in destroy_qp awaiting the last deref
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 need 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 <swise@opengridcomputing.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Doug Ledford <dledford@redhat.com>
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@ -475,7 +475,7 @@ struct c4iw_qp {
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struct t4_wq wq;
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spinlock_t lock;
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struct mutex mutex;
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atomic_t refcnt;
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struct kref kref;
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wait_queue_head_t wait;
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struct timer_list timer;
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int sq_sig_all;
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@ -683,17 +683,25 @@ static int build_inv_stag(union t4_wr *wqe, struct ib_send_wr *wr,
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return 0;
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}
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void _free_qp(struct kref *kref)
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{
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struct c4iw_qp *qhp;
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qhp = container_of(kref, struct c4iw_qp, kref);
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PDBG("%s qhp %p\n", __func__, qhp);
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kfree(qhp);
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}
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void c4iw_qp_add_ref(struct ib_qp *qp)
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{
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PDBG("%s ib_qp %p\n", __func__, qp);
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atomic_inc(&(to_c4iw_qp(qp)->refcnt));
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kref_get(&to_c4iw_qp(qp)->kref);
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}
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void c4iw_qp_rem_ref(struct ib_qp *qp)
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{
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PDBG("%s ib_qp %p\n", __func__, qp);
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if (atomic_dec_and_test(&(to_c4iw_qp(qp)->refcnt)))
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wake_up(&(to_c4iw_qp(qp)->wait));
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kref_put(&to_c4iw_qp(qp)->kref, _free_qp);
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}
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static void add_to_fc_list(struct list_head *head, struct list_head *entry)
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@ -1594,8 +1602,6 @@ int c4iw_destroy_qp(struct ib_qp *ib_qp)
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wait_event(qhp->wait, !qhp->ep);
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remove_handle(rhp, &rhp->qpidr, qhp->wq.sq.qid);
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atomic_dec(&qhp->refcnt);
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wait_event(qhp->wait, !atomic_read(&qhp->refcnt));
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spin_lock_irq(&rhp->lock);
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if (!list_empty(&qhp->db_fc_entry))
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@ -1608,8 +1614,9 @@ int c4iw_destroy_qp(struct ib_qp *ib_qp)
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destroy_qp(&rhp->rdev, &qhp->wq,
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ucontext ? &ucontext->uctx : &rhp->rdev.uctx);
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c4iw_qp_rem_ref(ib_qp);
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PDBG("%s ib_qp %p qpid 0x%0x\n", __func__, ib_qp, qhp->wq.sq.qid);
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kfree(qhp);
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return 0;
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}
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@ -1706,7 +1713,7 @@ struct ib_qp *c4iw_create_qp(struct ib_pd *pd, struct ib_qp_init_attr *attrs,
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init_completion(&qhp->rq_drained);
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mutex_init(&qhp->mutex);
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init_waitqueue_head(&qhp->wait);
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atomic_set(&qhp->refcnt, 1);
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kref_init(&qhp->kref);
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ret = insert_handle(rhp, &rhp->qpidr, qhp, qhp->wq.sq.qid);
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if (ret)
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