Subject: [resend, PATCH net-next v1 2/2] net: thunderbolt: Use separate header data type for the Rx

From: Andy Shevchenko <[email-masked]>
Date: Tue, 29 Nov 2022 18:13:59 +0200

The same data type structure is used for bitwise operations and
regular ones. It makes sparse unhappy, for example:

  .../thunderbolt.c:718:23: warning: cast to restricted __le32

  .../thunderbolt.c:953:23: warning: incorrect type in initializer (different base types)
  .../thunderbolt.c:953:23:    expected restricted __wsum [usertype] wsum
  .../thunderbolt.c:953:23:    got restricted __be32 [usertype]

Split the header to bitwise one and specific for Rx to make sparse
happy. Assure the layout by involving static_assert() against size
and offsets of the member of the structures.

Signed-off-by: Andy Shevchenko <[email-masked]>
---
 drivers/net/thunderbolt.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/net/thunderbolt.c b/drivers/net/thunderbolt.c
index 4dbc6c7f2e10..f7b3d0d4646c 100644
--- a/drivers/net/thunderbolt.c
+++ b/drivers/net/thunderbolt.c
@@ -58,12 +58,32 @@
  * supported then @frame_id is filled, otherwise it stays %0.
  */
 struct thunderbolt_ip_frame_header {
+	__le32 frame_size;
+	__le16 frame_index;
+	__le16 frame_id;
+	__le32 frame_count;
+};
+
+/* Same as &struct thunderbolt_ip_frame_header for Rx */
+struct thunderbolt_ip_frame_rx_hdr {
 	u32 frame_size;
 	u16 frame_index;
 	u16 frame_id;
 	u32 frame_count;
 };
 
+static_assert(sizeof(struct thunderbolt_ip_frame_header) ==
+	      sizeof(struct thunderbolt_ip_frame_rx_hdr));
+
+#define TBIP_FRAME_HDR_MATCH(x)							 \
+	static_assert(offsetof(struct thunderbolt_ip_frame_header, frame_##x) == \
+		      offsetof(struct thunderbolt_ip_frame_rx_hdr, frame_##x))
+TBIP_FRAME_HDR_MATCH(size);
+TBIP_FRAME_HDR_MATCH(index);
+TBIP_FRAME_HDR_MATCH(id);
+TBIP_FRAME_HDR_MATCH(count);
+#undef TBIP_FRAME_HDR_MATCH
+
 enum thunderbolt_ip_frame_pdf {
 	TBIP_PDF_FRAME_START = 1,
 	TBIP_PDF_FRAME_END,
@@ -193,7 +213,7 @@ struct tbnet {
 	struct delayed_work login_work;
 	struct work_struct connected_work;
 	struct work_struct disconnect_work;
-	struct thunderbolt_ip_frame_header rx_hdr;
+	struct thunderbolt_ip_frame_rx_hdr rx_hdr;
 	struct tbnet_ring rx_ring;
 	atomic_t frame_id;
 	struct tbnet_ring tx_ring;
-- 
2.35.1