On Tue, Apr 16, 2019 at 06:09:07AM -0700, Kaike Wan wrote: > commit 662d66466637862ef955f7f6e78a286d8cf0ebef upstream. > > When a QP is put into error state, all pending requests in the send > work queue should be drained. The following sequence of events could > lead to a failure, causing a request to hang: > (1) The QP builds a packet and tries to send through SDMA engine. > However, PIO engine is still busy. Consequently, this packet is put > on the QP's tx list and the QP is put on the PIO waiting list. The > field qp->s_flags is set with HFI1_S_WAIT_PIO_DRAIN; > (2) The QP is put into error state by the user application and > notify_error_qp() is called, which removes the QP from the PIO waiting > list and the packet from the QP's tx list. In addition, qp->s_flags > is cleared of RVT_S_ANY_WAIT_IO bits, which does not include > HFI1_S_WAIT_PIO_DRAIN bit; > (3) The hfi1_schdule_send() function is called to drain the QP's send > queue. Subsequently, hfi1_do_send() is called. Since the flag bit > HFI1_S_WAIT_PIO_DRAIN is set in qp->s_flags, hfi1_send_ok() fails. > As a result, hfi1_do_send() bails out without draining any request > from the send queue; > (4) The PIO engine completes the sending and tries to wake up any QP > on its waiting list. But the QP has been removed from the PIO waiting > list and therefore is kept in sleep forever. > > The fix is to clear qp->s_flags of HFI1_S_ANY_WAIT_IO bits in step (2). > HFI1_S_ANY_WAIT_IO includes RVT_S_ANY_WAIT_IO and HFI1_S_WAIT_PIO_DRAIN. Why are you sending this to stable with a different commit message than upstream has for the same commit? Jason
