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.
Fixes: 2e2ba09e48b7 ("IB/rdmavt, IB/hfi1: Create device dependent s_flags") Cc: stable@vger.kernel.org # 4.19.x+ Reviewed-by: Mike Marciniszyn mike.marciniszyn@intel.com Reviewed-by: Alex Estrin alex.estrin@intel.com Signed-off-by: Kaike Wan kaike.wan@intel.com Signed-off-by: Dennis Dalessandro dennis.dalessandro@intel.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com --- drivers/infiniband/hw/hfi1/qp.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/infiniband/hw/hfi1/qp.c b/drivers/infiniband/hw/hfi1/qp.c index 9b1e84a..63c5ba6 100644 --- a/drivers/infiniband/hw/hfi1/qp.c +++ b/drivers/infiniband/hw/hfi1/qp.c @@ -784,7 +784,7 @@ void notify_error_qp(struct rvt_qp *qp) write_seqlock(lock); if (!list_empty(&priv->s_iowait.list) && !(qp->s_flags & RVT_S_BUSY)) { - qp->s_flags &= ~RVT_S_ANY_WAIT_IO; + qp->s_flags &= ~HFI1_S_ANY_WAIT_IO; list_del_init(&priv->s_iowait.list); priv->s_iowait.lock = NULL; rvt_put_qp(qp);
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
Oops, copy/paste messed up the spacing. I will resend it.
Kaike
-----Original Message----- From: linux-rdma-owner@vger.kernel.org [mailto:linux-rdma- owner@vger.kernel.org] On Behalf Of Jason Gunthorpe Sent: Thursday, April 18, 2019 2:23 AM To: Wan, Kaike kaike.wan@intel.com Cc: stable@vger.kernel.org; linux-rdma@vger.kernel.org; stable- commits@vger.kernel.org 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
linux-stable-mirror@lists.linaro.org
-
Jason Gunthorpe -
Kaike Wan -
Wan, Kaike