Re: [PATCH] core/verb.c: fix kernel panic: always initialize struct ib_qp *qp->usecnt

Roland Dreier
2012-01-20T18:43:51Z

On Fri, Jan 20, 2012 at 10:40 AM, Roland Dreier <roland-BHEL68pLQRGGvPXPguhicg@public.gmane.org> wrote:
> On Fri, Jan 20, 2012 at 8:14 AM, Bernd Schubert
> <bernd.schubert-mPn0NPGs4xGatNDF+KUbs4QuADTiUCJX@public.gmane.org> wrote:
>> I *guess* the qp allocated by pd->context->ops.create_qp() does not have
>> qp->usecnt initialized (not does it know anything about it). So its random
>> value will fail the destruction later. A simple workaround that would work
>> for us, is to extend the patch I send to
>>
>> diff --git a/drivers/infiniband/core/verbs.c
>> b/drivers/infiniband/core/verbs.c
>> index 602b1bd..fba1675 100644
>> --- a/drivers/infiniband/core/verbs.c
>> +++ b/drivers/infiniband/core/verbs.c
>> @@ -874,7 +874,7 @@ int ib_destroy_qp(struct ib_qp *qp)
>>        struct ib_srq *srq;
>>        int ret;
>>
>> -       if (atomic_read(&qp->usecnt))
>> +       if (qp->qp_type == IB_QPT_XRC_TGT && atomic_read(&qp->usecnt))
>>                return -EBUSY;
>>
>>        if (qp->real_qp != qp)
>
> It looks like this is sufficient and correct without the other patch?

But maybe it's cleaner to initialize qp->usecnt in
both ib_create_qp() and ib_uverbs_create_qp().

- R.