Oops, copy/paste messed up the spacing. I will resend it. Kaike > -----Original Message----- > From: linux-rdma-owner@xxxxxxxxxxxxxxx [mailto:linux-rdma- > owner@xxxxxxxxxxxxxxx] On Behalf Of Jason Gunthorpe > Sent: Thursday, April 18, 2019 2:23 AM > To: Wan, Kaike <kaike.wan@xxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx; linux-rdma@xxxxxxxxxxxxxxx; stable- > commits@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] IB/hfi1: Failed to drain send queue when QP is put into > error state > > 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
