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From:   Arnd Bergmann <arnd@kernel.org>
To:     Edward Cree <ecree.xilinx@gmail.com>,
        Martin Habets <habetsm.xilinx@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>
Cc:     Arnd Bergmann <arnd@arndb.de>, netdev@vger.kernel.org,
        linux-net-drivers@amd.com, linux-kernel@vger.kernel.org
Subject: [PATCH 3/3] sfc: selftest: fix struct packing
Date:   Mon, 19 Jun 2023 11:12:11 +0200
Message-Id: <20230619091215.2731541-3-arnd@kernel.org>
In-Reply-To: <20230619091215.2731541-1-arnd@kernel.org>
References: <20230619091215.2731541-1-arnd@kernel.org>
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From: Arnd Bergmann <arnd@arndb.de>

Three of the sfc drivers define a packed loopback_payload structure with an
ethernet header followed by an IP header. However, the kernel definition
of iphdr specifies that this is 4-byte aligned, causing a W=1 warning:

net/ethernet/sfc/siena/selftest.c:46:15: error: field ip within 'struct efx_loopback_payload' is less aligned than 'struct iphdr' and is usually due to 'struct efx_loopback_payload' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
        struct iphdr ip;

As the iphdr packing is not easily changed without breaking other code,
change the three structures to use a local definition instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/sfc/falcon/selftest.c | 21 ++++++++++++++++++++-
 drivers/net/ethernet/sfc/selftest.c        | 21 ++++++++++++++++++++-
 drivers/net/ethernet/sfc/siena/selftest.c  | 21 ++++++++++++++++++++-
 3 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/sfc/falcon/selftest.c b/drivers/net/ethernet/sfc/falcon/selftest.c
index 6a454ac6f8763..fb7fcd27a33a5 100644
--- a/drivers/net/ethernet/sfc/falcon/selftest.c
+++ b/drivers/net/ethernet/sfc/falcon/selftest.c
@@ -40,7 +40,26 @@
  */
 struct ef4_loopback_payload {
 	struct ethhdr header;
-	struct iphdr ip;
+	struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+		__u8	ihl:4,
+			version:4;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+		__u8	version:4,
+			ihl:4;
+#else
+#error	"Please fix <asm/byteorder.h>"
+#endif
+		__u8	tos;
+		__be16	tot_len;
+		__be16	id;
+		__be16	frag_off;
+		__u8	ttl;
+		__u8	protocol;
+		__sum16	check;
+		__be32	saddr;
+		__be32	daddr;
+	} __packed ip; /* unaligned struct iphdr */
 	struct udphdr udp;
 	__be16 iteration;
 	char msg[64];
diff --git a/drivers/net/ethernet/sfc/selftest.c b/drivers/net/ethernet/sfc/selftest.c
index 3c5227afd4977..440a57953779c 100644
--- a/drivers/net/ethernet/sfc/selftest.c
+++ b/drivers/net/ethernet/sfc/selftest.c
@@ -43,7 +43,26 @@
  */
 struct efx_loopback_payload {
 	struct ethhdr header;
-	struct iphdr ip;
+	struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+		__u8	ihl:4,
+			version:4;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+		__u8	version:4,
+			ihl:4;
+#else
+#error	"Please fix <asm/byteorder.h>"
+#endif
+		__u8	tos;
+		__be16	tot_len;
+		__be16	id;
+		__be16	frag_off;
+		__u8	ttl;
+		__u8	protocol;
+		__sum16	check;
+		__be32	saddr;
+		__be32	daddr;
+	} __packed ip; /* unaligned struct iphdr */
 	struct udphdr udp;
 	__be16 iteration;
 	char msg[64];
diff --git a/drivers/net/ethernet/sfc/siena/selftest.c b/drivers/net/ethernet/sfc/siena/selftest.c
index 07715a3d6beab..b8a8b0495f661 100644
--- a/drivers/net/ethernet/sfc/siena/selftest.c
+++ b/drivers/net/ethernet/sfc/siena/selftest.c
@@ -43,7 +43,26 @@
  */
 struct efx_loopback_payload {
 	struct ethhdr header;
-	struct iphdr ip;
+	struct {
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+		__u8	ihl:4,
+			version:4;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+		__u8	version:4,
+			ihl:4;
+#else
+#error	"Please fix <asm/byteorder.h>"
+#endif
+		__u8	tos;
+		__be16	tot_len;
+		__be16	id;
+		__be16	frag_off;
+		__u8	ttl;
+		__u8	protocol;
+		__sum16	check;
+		__be32	saddr;
+		__be32	daddr;
+	} __packed ip; /* unaligned struct iphdr */
 	struct udphdr udp;
 	__be16 iteration;
 	char msg[64];
-- 
2.39.2