IB/cache: Restore compatibility for ib_query_gid

Code changes in smc have become so complicated this cycle that the RDMA
patches to remove ib_query_gid in smc create too complex merge conflicts.
Allow those conflicts to be resolved by using the net/smc hunks by
providing a compatibility wrapper. During the second phase of the merge
window this wrapper will be deleted and smc updated to use the new API.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

include/rdma/ib_cache.h

@@ -132,4 +132,28 @@ const struct ib_gid_attr *rdma_get_gid_attr(struct ib_device *device,
 					    u8 port_num, int index);
 void rdma_put_gid_attr(const struct ib_gid_attr *attr);
 void rdma_hold_gid_attr(const struct ib_gid_attr *attr);
+
+/*
+ * This is to be removed. It only exists to make merging rdma and smc simpler.
+ */
+static inline __deprecated int ib_query_gid(struct ib_device *device,
+					    u8 port_num, int index,
+					    union ib_gid *gid,
+					    struct ib_gid_attr *attr_out)
+{
+	const struct ib_gid_attr *attr;
+
+	attr = rdma_get_gid_attr(device, port_num, index);
+	if (IS_ERR(attr))
+		return PTR_ERR(attr);
+
+	if (attr->ndev)
+		dev_hold(attr->ndev);
+	*attr_out = *attr;
+
+	rdma_put_gid_attr(attr);
+
+	return 0;
+}
+
 #endif /* _IB_CACHE_H */