Commit 51b2e351 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Greg Kroah-Hartman

IB/hfi1: Fix defered ack race with qp destroy

commit 72f53af2651957b0b9d6dead72a393eaf9a2c3be upstream.

There is a a bug in defered ack stuff that causes a race with the
destroy of a QP.

A packet causes a defered ack to be pended by putting the QP
into an rcd queue.

A return from the driver interrupt processing will process that rcd
queue of QPs and attempt to do a direct send of the ack.   At this
point no locks are held and the above QP could now be put in the reset
state in the qp destroy logic.   A refcount protects the QP while it
is in the rcd queue so it isn't going anywhere yet.

If the direct send fails to allocate a pio buffer,
hfi1_schedule_send() is called to trigger sending an ack from the
send engine. There is no state test in that code path.

The refcount is then dropped from the driver.c caller
potentially allowing the qp destroy to continue from its
refcount wait in parallel with the workqueue scheduling of the qp.
Reviewed-by: default avatarDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: default avatarDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9ae3f9e1
......@@ -932,8 +932,10 @@ void hfi1_send_rc_ack(struct hfi1_ctxtdata *rcd, struct rvt_qp *qp,
return;
queue_ack:
this_cpu_inc(*ibp->rvp.rc_qacks);
spin_lock_irqsave(&qp->s_lock, flags);
if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK))
goto unlock;
this_cpu_inc(*ibp->rvp.rc_qacks);
qp->s_flags |= RVT_S_ACK_PENDING | RVT_S_RESP_PENDING;
qp->s_nak_state = qp->r_nak_state;
qp->s_ack_psn = qp->r_ack_psn;
......@@ -942,6 +944,7 @@ queue_ack:
/* Schedule the send tasklet. */
hfi1_schedule_send(qp);
unlock:
spin_unlock_irqrestore(&qp->s_lock, flags);
}
......
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