Re: [PATCH for-rc 4/6] RDMA/bnxt_re: Synchronize destroy_qp with poll_cq

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Thu, Feb 15, 2018 at 09:20:11PM -0800, Selvin Xavier wrote:
> Avoid system crash when destroy_qp is invoked while
> the driver is processing the poll_cq. Synchronize these
> functions using the cq_lock.
>
> Signed-off-by: Selvin Xavier <selvin.xavier-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
> ---
>  drivers/infiniband/hw/bnxt_re/ib_verbs.c | 39 +++++++++++++++++++++++++++++---
>  drivers/infiniband/hw/bnxt_re/ib_verbs.h |  2 ++
>  drivers/infiniband/hw/bnxt_re/qplib_fp.c | 21 +++++------------
>  drivers/infiniband/hw/bnxt_re/qplib_fp.h |  4 +++-
>  4 files changed, 47 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/infiniband/hw/bnxt_re/ib_verbs.c b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
> index b7eb104..9cb9928 100644
> --- a/drivers/infiniband/hw/bnxt_re/ib_verbs.c
> +++ b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
> @@ -786,20 +786,51 @@ int bnxt_re_query_ah(struct ib_ah *ib_ah, struct rdma_ah_attr *ah_attr)
>  	return 0;
>  }
>
> +static unsigned long bnxt_re_lock_cqs(struct bnxt_re_qp *qp)
> +	__acquires(&qp->scq->cq_lock) __acquires(&qp->rcq->cq_lock)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&qp->scq->cq_lock, flags);
> +	if (qp->rcq != qp->scq)
> +		spin_lock(&qp->rcq->cq_lock);
> +	else
> +		__acquire(&qp->rcq->cq_lock);

Sorry for naive question, why do you need __acquire/__release? And why
can't spin_is_locked(&qp->rcq->cq_lock) be used for unlock code?


> +
> +	return flags;
> +}
> +
> +static void bnxt_re_unlock_cqs(struct bnxt_re_qp *qp,
> +			       unsigned long flags)
> +	__releases(&qp->scq->cq_lock) __releases(&qp->rcq->cq_lock)
> +{
> +	if (qp->rcq != qp->scq)
> +		spin_unlock(&qp->rcq->cq_lock);
> +	else
> +		__release(&qp->rcq->cq_lock);
> +	spin_unlock_irqrestore(&qp->scq->cq_lock, flags);
> +}
> +

Thanks

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