Re: [PATCH for-rc v2] RDMA/bnxt_re: Fix error recovery sequence

[Leon Romanovsky <leon@kernel.org>]

On Mon, Dec 23, 2024 at 09:12:53PM +0530, Kalesh Anakkur Purayil wrote:
> Regards,
> Kalesh AP
> 
> 
> On Mon, 23 Dec 2024 at 8:30 PM, Leon Romanovsky <leon@kernel.org> wrote:
> 
> > On Fri, Dec 20, 2024 at 01:29:20PM +0530, Kalesh AP wrote:
> > > Fixed to return ENXIO from __send_message_basic_sanity()
> > > to indicate that device is in error state. In the case of
> > > ERR_DEVICE_DETACHED state, the driver should not post the
> > > commands to the firmware as it will time out eventually.
> > >
> > > Removed bnxt_re_modify_qp() call from bnxt_re_dev_stop()
> > > as it is a no-op.
> > >
> > > Fixes: cc5b9b48d447 ("RDMA/bnxt_re: Recover the device when FW error is
> > detected")
> > > Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
> > > Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
> > > Reviewed-by: Selvin Xavier <selvin.xavier@broadcom.com>
> > > ---
> > > V2: No changes since v1 and is just a resend.
> > > V1:
> > https://patchwork.kernel.org/project/linux-rdma/patch/20241204075416.478431-5-kalesh-anakkur.purayil@broadcom.com/
> > > ---
> > >  drivers/infiniband/hw/bnxt_re/main.c       | 8 +-------
> > >  drivers/infiniband/hw/bnxt_re/qplib_rcfw.c | 7 ++++---
> > >  drivers/infiniband/hw/bnxt_re/qplib_rcfw.h | 3 +++
> > >  3 files changed, 8 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/drivers/infiniband/hw/bnxt_re/main.c
> > b/drivers/infiniband/hw/bnxt_re/main.c
> > > index b7af0d5ff3b6..c143f273b759 100644
> > > --- a/drivers/infiniband/hw/bnxt_re/main.c
> > > +++ b/drivers/infiniband/hw/bnxt_re/main.c
> > > @@ -1715,11 +1715,8 @@ static bool bnxt_re_is_qp1_or_shadow_qp(struct
> > bnxt_re_dev *rdev,
> > >
> > >  static void bnxt_re_dev_stop(struct bnxt_re_dev *rdev)
> > >  {
> > > -     int mask = IB_QP_STATE;
> > > -     struct ib_qp_attr qp_attr;
> > >       struct bnxt_re_qp *qp;
> > >
> > > -     qp_attr.qp_state = IB_QPS_ERR;
> > >       mutex_lock(&rdev->qp_lock);
> > >       list_for_each_entry(qp, &rdev->qp_list, list) {
> > >               /* Modify the state of all QPs except QP1/Shadow QP */
> > > @@ -1727,12 +1724,9 @@ static void bnxt_re_dev_stop(struct bnxt_re_dev
> > *rdev)
> > >                       if (qp->qplib_qp.state !=
> > >                           CMDQ_MODIFY_QP_NEW_STATE_RESET &&
> > >                           qp->qplib_qp.state !=
> > > -                         CMDQ_MODIFY_QP_NEW_STATE_ERR) {
> > > +                         CMDQ_MODIFY_QP_NEW_STATE_ERR)
> > >                               bnxt_re_dispatch_event(&rdev->ibdev,
> > &qp->ib_qp,
> > >                                                      1,
> > IB_EVENT_QP_FATAL);
> > > -                             bnxt_re_modify_qp(&qp->ib_qp, &qp_attr,
> > mask,
> > > -                                               NULL);
> > > -                     }
> > >               }
> > >       }
> > >       mutex_unlock(&rdev->qp_lock);
> > > diff --git a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
> > b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
> > > index 5e90ea232de8..c8e65169f58a 100644
> > > --- a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
> > > +++ b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.c
> > > @@ -423,8 +423,9 @@ static int __send_message_basic_sanity(struct
> > bnxt_qplib_rcfw *rcfw,
> > >       cmdq = &rcfw->cmdq;
> > >
> > >       /* Prevent posting if f/w is not in a state to process */
> > > -     if (test_bit(ERR_DEVICE_DETACHED, &rcfw->cmdq.flags))
> > > -             return bnxt_qplib_map_rc(opcode);
> > > +     if (RCFW_NO_FW_ACCESS(rcfw))
> > > +             return -ENXIO;
> > > +
> > >       if (test_bit(FIRMWARE_STALL_DETECTED, &cmdq->flags))
> > >               return -ETIMEDOUT;
> > >
> > > @@ -493,7 +494,7 @@ static int __bnxt_qplib_rcfw_send_message(struct
> > bnxt_qplib_rcfw *rcfw,
> > >
> > >       rc = __send_message_basic_sanity(rcfw, msg, opcode);
> > >       if (rc)
> > > -             return rc;
> > > +             return rc == -ENXIO ? bnxt_qplib_map_rc(opcode) : rc;
> > >
> > >       rc = __send_message(rcfw, msg, opcode);
> > >       if (rc)
> > > diff --git a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.h
> > b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.h
> > > index 88814cb3aa74..4f7d800e35c3 100644
> > > --- a/drivers/infiniband/hw/bnxt_re/qplib_rcfw.h
> > > +++ b/drivers/infiniband/hw/bnxt_re/qplib_rcfw.h
> > > @@ -129,6 +129,9 @@ static inline u32 bnxt_qplib_set_cmd_slots(struct
> > cmdq_base *req)
> > >
> > >  #define RCFW_MAX_COOKIE_VALUE                (BNXT_QPLIB_CMDQE_MAX_CNT
> > - 1)
> > >  #define RCFW_CMD_IS_BLOCKING         0x8000
> > > +#define RCFW_NO_FW_ACCESS(rcfw)
> >       \
> > > +     (test_bit(ERR_DEVICE_DETACHED, &(rcfw)->cmdq.flags) ||          \
> > > +      pci_channel_offline((rcfw)->pdev))
> >
> > You promised me that this patch handles races, so how is this
> > pci_channel_offline() check protected?
> >
> > Thansk
> 
> Hi Leon,
> 
> Sorry, I may be missing something here.
> Could you help me understand what is the race condition here? I can then
> internally discuss with the team based on your input.

pci_channel_offline() is placed completely randomly here. There is no
guarantee that PCI card won't be offline immediately after this check.

Thanks


> 
> Regards,
> Kalesh AP
> 
> >
> >
> > >
> > >  #define HWRM_VERSION_DEV_ATTR_MAX_DPI  0x1000A0000000DULL
> > >  /* HWRM version 1.10.3.18 */
> > > --
> > > 2.43.5
> > >
> >