On Fri, Feb 16, 2018 at 1:08 PM, Leon Romanovsky <leon@xxxxxxxxxx> wrote:
> 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@xxxxxxxxxxxx>
>> ---
>> 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?
>
I used __acquire and __release for satisfying the sparse. Sparse used to
give warnings "context imbalance - wrong count at exit" since the locking
and unlocking happens from two different functions. seen similar implementation
in other drivers too.
I feel spin_is_locked also can be used.. but it doesn't avoid the RCQ
!= SCQ check.
Also, if feel the code symmetry is better in this way.
>
>> +
>> + 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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