RDMA/ucma: Return stable IB device index as identifier

The librdmacm uses node_guid as identifier to correlate between IB devices
and CMA devices. However FW resets cause to such "connection" to be lost
and require from the user to restart its application.

Extend UCMA to return IB device index, which is stable identifier.

Link: https://lore.kernel.org/r/20200504132541.355710-1-leon@kernel.org
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/ucma.c

@@ -845,7 +845,7 @@ static ssize_t ucma_query_route(struct ucma_file *file,
 	struct sockaddr *addr;
 	int ret = 0;
 
-	if (out_len < sizeof(resp))
+	if (out_len < offsetof(struct rdma_ucm_query_route_resp, ibdev_index))
 		return -ENOSPC;
 
 	if (copy_from_user(&cmd, inbuf, sizeof(cmd)))
@@ -869,6 +869,7 @@ static ssize_t ucma_query_route(struct ucma_file *file,
 		goto out;
 
 	resp.node_guid = (__force __u64) ctx->cm_id->device->node_guid;
+	resp.ibdev_index = ctx->cm_id->device->index;
 	resp.port_num = ctx->cm_id->port_num;
 
 	if (rdma_cap_ib_sa(ctx->cm_id->device, ctx->cm_id->port_num))
@@ -880,8 +881,8 @@ static ssize_t ucma_query_route(struct ucma_file *file,
 
 out:
 	mutex_unlock(&ctx->mutex);
-	if (copy_to_user(u64_to_user_ptr(cmd.response),
-			 &resp, sizeof(resp)))
+	if (copy_to_user(u64_to_user_ptr(cmd.response), &resp,
+			 min_t(size_t, out_len, sizeof(resp))))
 		ret = -EFAULT;
 
 	ucma_put_ctx(ctx);
@@ -895,6 +896,7 @@ static void ucma_query_device_addr(struct rdma_cm_id *cm_id,
 		return;
 
 	resp->node_guid = (__force __u64) cm_id->device->node_guid;
+	resp->ibdev_index = cm_id->device->index;
 	resp->port_num = cm_id->port_num;
 	resp->pkey = (__force __u16) cpu_to_be16(
 		     ib_addr_get_pkey(&cm_id->route.addr.dev_addr));
@@ -907,7 +909,7 @@ static ssize_t ucma_query_addr(struct ucma_context *ctx,
 	struct sockaddr *addr;
 	int ret = 0;
 
-	if (out_len < sizeof(resp))
+	if (out_len < offsetof(struct rdma_ucm_query_addr_resp, ibdev_index))
 		return -ENOSPC;
 
 	memset(&resp, 0, sizeof resp);
@@ -922,7 +924,7 @@ static ssize_t ucma_query_addr(struct ucma_context *ctx,
 
 	ucma_query_device_addr(ctx->cm_id, &resp);
 
-	if (copy_to_user(response, &resp, sizeof(resp)))
+	if (copy_to_user(response, &resp, min_t(size_t, out_len, sizeof(resp))))
 		ret = -EFAULT;
 
 	return ret;
@@ -974,7 +976,7 @@ static ssize_t ucma_query_gid(struct ucma_context *ctx,
 	struct sockaddr_ib *addr;
 	int ret = 0;
 
-	if (out_len < sizeof(resp))
+	if (out_len < offsetof(struct rdma_ucm_query_addr_resp, ibdev_index))
 		return -ENOSPC;
 
 	memset(&resp, 0, sizeof resp);
@@ -1007,7 +1009,7 @@ static ssize_t ucma_query_gid(struct ucma_context *ctx,
 						    &ctx->cm_id->route.addr.dst_addr);
 	}
 
-	if (copy_to_user(response, &resp, sizeof(resp)))
+	if (copy_to_user(response, &resp, min_t(size_t, out_len, sizeof(resp))))
 		ret = -EFAULT;
 
 	return ret;

include/uapi/rdma/rdma_user_cm.h

@@ -164,6 +164,8 @@ struct rdma_ucm_query_route_resp {
 	__u32 num_paths;
 	__u8 port_num;
 	__u8 reserved[3];
+	__u32 ibdev_index;
+	__u32 reserved1;
 };
 
 struct rdma_ucm_query_addr_resp {
@@ -175,6 +177,8 @@ struct rdma_ucm_query_addr_resp {
 	__u16 dst_size;
 	struct __kernel_sockaddr_storage src_addr;
 	struct __kernel_sockaddr_storage dst_addr;
+	__u32 ibdev_index;
+	__u32 reserved1;
 };
 
 struct rdma_ucm_query_path_resp {