> On Jun 23, 2023, at 2:37 PM, Tom Talpey <tom@xxxxxxxxxx> wrote:
>
> On 6/14/2023 10:00 AM, Chuck Lever wrote:
>> From: Chuck Lever <chuck.lever@xxxxxxxxxx>
>> Have the iwarp side properly set the ndev in the device's sgid_attrs
>> so that address resolution can treat it more like a RoCE device.
>> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>> ---
>> drivers/infiniband/core/cache.c | 12 ++++++++++++
>> 1 file changed, 12 insertions(+)
>> diff --git a/drivers/infiniband/core/cache.c b/drivers/infiniband/core/cache.c
>> index 2e91d8879326..717524fe8a39 100644
>> --- a/drivers/infiniband/core/cache.c
>> +++ b/drivers/infiniband/core/cache.c
>> @@ -1439,6 +1439,7 @@ static int config_non_roce_gid_cache(struct ib_device *device,
>> {
>> struct ib_gid_attr gid_attr = {};
>> struct ib_gid_table *table;
>> + struct net_device *ndev;
>> int ret = 0;
>> int i;
>> @@ -1457,10 +1458,21 @@ static int config_non_roce_gid_cache(struct ib_device *device,
>> i);
>> goto err;
>> }
>> +
>> + ndev = NULL;
>> + if (rdma_protocol_iwarp(device, port)) {
>> + ndev = ib_device_get_netdev(device, port);
>> + if (!ndev)
>> + continue;
>> + RCU_INIT_POINTER(gid_attr.ndev, ndev);
>> + }
>> +
>> gid_attr.index = i;
>> tprops->subnet_prefix =
>> be64_to_cpu(gid_attr.gid.global.subnet_prefix);
>> add_modify_gid(table, &gid_attr);
>> +
>> + dev_put(ndev);
>
> I'm not sure about two things here...
>
> 1) is it correct to dev_put(ndev) when returning? It seems that this
> may risk the device may vanish when it's still present in the cache.
> Feel free to tell me I'm confused.
ib_device_get_netdev() increments the ndev's reference count
before returning. dev_put() releases that reference.
> 2) Assuming yes, shouldn't the dev_put(ndev) move to within the new
> if(iwarp) block just above?
If the "if (iwarp)" block isn't taken, then ndev is NULL and that
makes the dev_put() a no-op.
> Tom.
>
>> }
>> err:
>> mutex_unlock(&table->lock);
--
Chuck Lever
