On Thu, Aug 05, 2021 at 10:36:03AM +0800, YueHaibing wrote:

On 2021/8/4 21:53, Leon Romanovsky wrote:

quoted

On Wed, Aug 04, 2021 at 08:59:39PM +0800, YueHaibing wrote:

quoted

If re-registering an MR in hns_roce_rereg_user_mr(), we should
return NULL instead of pass 0 to ERR_PTR.

Fixes: 4e9fc1dae2a9 ("RDMA/hns: Optimize the MR registration process")
Signed-off-by: YueHaibing <redacted>
---
 drivers/infiniband/hw/hns/hns_roce_mr.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_mr.c b/drivers/infiniband/hw/hns/hns_roce_mr.c
index 006c84bb3f9f..7089ac780291 100644
--- a/drivers/infiniband/hw/hns/hns_roce_mr.c
+++ b/drivers/infiniband/hw/hns/hns_roce_mr.c

@@ -352,7 +352,9 @@ struct ib_mr *hns_roce_rereg_user_mr(struct ib_mr *ibmr, int flags, u64 start,
 free_cmd_mbox:
 	hns_roce_free_cmd_mailbox(hr_dev, mailbox);
 
-	return ERR_PTR(ret);
+	if (ret)
+		return ERR_PTR(ret);
+	return NULL;
 }

I don't understand this function, it returns or ERR_PTR() or NULL, but
should return &mr->ibmr in success path. How does it work?

Did you means hns_roce_reg_user_mr()?

hns_roce_rereg_user_mr() returns ERR_PTR() on failure, and return NULL on success,

In ib_uverbs_rereg_mr(), old mr will be used if rereg_user_mr() return NULL, see:

 829         new_mr = ib_dev->ops.rereg_user_mr(mr, cmd.flags, cmd.start, cmd.length,
 830                                            cmd.hca_va, cmd.access_flags, new_pd,
 831                                            &attrs->driver_udata);
 832         if (IS_ERR(new_mr)) {
 833                 ret = PTR_ERR(new_mr);
 834                 goto put_new_uobj;
 835         }
 836         if (new_mr) {
.....
 860                 mr = new_mr;
 861         } else {
 862                 if (cmd.flags & IB_MR_REREG_PD) {
 863                         atomic_dec(&orig_pd->usecnt);
 864                         mr->pd = new_pd;
 865                         atomic_inc(&new_pd->usecnt);
 866                 }
 867                 if (cmd.flags & IB_MR_REREG_TRANS)
 868                         mr->iova = cmd.hca_va;
 869         }

You overwrite various fields in old_mr when executing hns_roce_rereg_user_mr().
For example mr->access flags, which is not returned to the original
state after all failures.

Also I'm not so sure about if it is valid to return NULL in all flows.

Thanks

quoted

Thanks

quoted

 
 int hns_roce_dereg_mr(struct ib_mr *ibmr, struct ib_udata *udata)
-- 
2.17.1

.