[PATCH][next] iavf: Replace one-element array in struct virtchnl_vlan_filter_list

From: Gustavo A. R. Silva
Date: Tue May 25 2021 - 19:05:20 EST


There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Refactor the code according to the use of a flexible-array member in struct
virtchnl_vlan_filter_list instead of one-element array, and use the
struct_size() and flex_array_size() helpers.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
---
drivers/net/ethernet/intel/iavf/iavf_virtchnl.c | 12 ++++--------
include/linux/avf/virtchnl.h | 7 ++++---
2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
index b2392af4e048..167955094170 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_virtchnl.c
@@ -573,15 +573,13 @@ void iavf_add_vlans(struct iavf_adapter *adapter)
}
adapter->current_op = VIRTCHNL_OP_ADD_VLAN;

- len = sizeof(struct virtchnl_vlan_filter_list) +
- (count * sizeof(u16));
+ len = struct_size(vvfl, vlan_id, count);
if (len > IAVF_MAX_AQ_BUF_SIZE) {
dev_warn(&adapter->pdev->dev, "Too many add VLAN changes in one request\n");
count = (IAVF_MAX_AQ_BUF_SIZE -
sizeof(struct virtchnl_vlan_filter_list)) /
sizeof(u16);
- len = sizeof(struct virtchnl_vlan_filter_list) +
- (count * sizeof(u16));
+ len = struct_size(vvfl, vlan_id, count);
more = true;
}
vvfl = kzalloc(len, GFP_ATOMIC);
@@ -643,15 +641,13 @@ void iavf_del_vlans(struct iavf_adapter *adapter)
}
adapter->current_op = VIRTCHNL_OP_DEL_VLAN;

- len = sizeof(struct virtchnl_vlan_filter_list) +
- (count * sizeof(u16));
+ len = struct_size(vvfl, vlan_id, count);
if (len > IAVF_MAX_AQ_BUF_SIZE) {
dev_warn(&adapter->pdev->dev, "Too many delete VLAN changes in one request\n");
count = (IAVF_MAX_AQ_BUF_SIZE -
sizeof(struct virtchnl_vlan_filter_list)) /
sizeof(u16);
- len = sizeof(struct virtchnl_vlan_filter_list) +
- (count * sizeof(u16));
+ len = struct_size(vvfl, vlan_id, count);
more = true;
}
vvfl = kzalloc(len, GFP_ATOMIC);
diff --git a/include/linux/avf/virtchnl.h b/include/linux/avf/virtchnl.h
index 15b982911321..9b9d79c270b1 100644
--- a/include/linux/avf/virtchnl.h
+++ b/include/linux/avf/virtchnl.h
@@ -444,10 +444,10 @@ VIRTCHNL_CHECK_STRUCT_LEN(12, virtchnl_ether_addr_list);
struct virtchnl_vlan_filter_list {
u16 vsi_id;
u16 num_elements;
- u16 vlan_id[1];
+ u16 vlan_id[];
};

-VIRTCHNL_CHECK_STRUCT_LEN(6, virtchnl_vlan_filter_list);
+VIRTCHNL_CHECK_STRUCT_LEN(4, virtchnl_vlan_filter_list);

/* VIRTCHNL_OP_CONFIG_PROMISCUOUS_MODE
* VF sends VSI id and flags.
@@ -1037,7 +1037,8 @@ virtchnl_vc_validate_vf_msg(struct virtchnl_version_info *ver, u32 v_opcode,
if (msglen >= valid_len) {
struct virtchnl_vlan_filter_list *vfl =
(struct virtchnl_vlan_filter_list *)msg;
- valid_len += vfl->num_elements * sizeof(u16);
+ valid_len += flex_array_size(vfl, vlan_id,
+ vfl->num_elements);
if (vfl->num_elements == 0)
err_msg_format = true;
}
--
2.27.0