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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>
This commit is contained in:
Steve Wise 2016-07-29 11:00:54 -07:00 committed by Doug Ledford
parent 1b1a889dbb
commit ad61a4c7a9
2 changed files with 15 additions and 8 deletions
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2
drivers/infiniband/hw/cxgb4/iw_cxgb4.h
View File

@ -475,7 +475,7 @@ 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;

21
drivers/infiniband/hw/cxgb4/qp.c
View File

@ -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)
@ -1594,8 +1602,6 @@ 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))
@ -1608,8 +1614,9 @@ 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;
}
@ -1706,7 +1713,7 @@ 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)