4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx> 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: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx> Signed-off-by: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx> Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/infiniband/hw/hfi1/rc.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/infiniband/hw/hfi1/rc.c +++ b/drivers/infiniband/hw/hfi1/rc.c @@ -932,8 +932,10 @@ void hfi1_send_rc_ack(struct hfi1_ctxtda 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); } -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html