Re: [PATCH v3 10/14] RDMA/ionic: Register device ops for control path

Abhijit Gangurde
2025-07-03T07:19:44Z

On 7/2/25 23:30, Leon Romanovsky wrote:
> On Wed, Jul 02, 2025 at 10:18:03AM -0300, Jason Gunthorpe wrote:
>> On Tue, Jul 01, 2025 at 01:38:44PM +0300, Leon Romanovsky wrote:
>>>> +static void ionic_flush_qs(struct ionic_ibdev *dev)
>>>> +{
>>>> + struct ionic_qp *qp, *qp_tmp;
>>>> + struct ionic_cq *cq, *cq_tmp;
>>>> + LIST_HEAD(flush_list);
>>>> + unsigned long index;
>>>> +
>>>> + /* Flush qp send and recv */
>>>> + rcu_read_lock();
>>>> + xa_for_each(&dev->qp_tbl, index, qp) {
>>>> + kref_get(&qp->qp_kref);
>>>> + list_add_tail(&qp->ibkill_flush_ent, &flush_list);
>>>> + }
>>>> + rcu_read_unlock();
>>> Same question as for CQ. What does RCU lock protect here?
>> It should protect the kref_get against free of qp. The qp memory must
>> be RCU freed.
> I'm not sure that this was intension here. Let's wait for an answer from the author.

As Jason mentioned, It was intended to protect the kref_get against free
of cq and qp
in the destroy path.

>> But this pattern requires kref_get_unless_zero()
>>
>> Jason

I will change it for kref_get_unless_zero().

Thanks,
Abhijit