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From:   Alex Elder <elder@linaro.org>
To:     subashab@codeaurora.org, stranche@codeaurora.org,
        davem@davemloft.net, kuba@kernel.org
Cc:     sharathv@codeaurora.org, bjorn.andersson@linaro.org,
        evgreen@chromium.org, cpratapa@codeaurora.org,
        David.Laight@ACULAB.COM, olteanv@gmail.com,
        alexander.duyck@gmail.com, elder@kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alexander Duyck <alexanderduyck@fb.com>
Subject: [PATCH net-next v6 5/6] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum trailer
Date:   Mon, 15 Mar 2021 16:51:50 -0500
Message-Id: <20210315215151.3029676-6-elder@linaro.org>
In-Reply-To: <20210315215151.3029676-1-elder@linaro.org>
References: <20210315215151.3029676-1-elder@linaro.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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Replace the use of C bit-fields in the rmnet_map_dl_csum_trailer
structure with a single one-byte field, using constant field masks
to encode or get at embedded values.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
---
v3: - Use BIT(x) and don't use u8_get_bits() for the checksum valid flag

 .../ethernet/qualcomm/rmnet/rmnet_map_data.c    |  2 +-
 include/linux/if_rmnet.h                        | 17 +++++++----------
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index e7d0394cb2979..c336c17e01fe4 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -359,7 +359,7 @@ int rmnet_map_checksum_downlink_packet(struct sk_buff *skb, u16 len)
 
 	csum_trailer = (struct rmnet_map_dl_csum_trailer *)(skb->data + len);
 
-	if (!csum_trailer->valid) {
+	if (!(csum_trailer->flags & MAP_CSUM_DL_VALID_FLAG)) {
 		priv->stats.csum_valid_unset++;
 		return -EINVAL;
 	}
diff --git a/include/linux/if_rmnet.h b/include/linux/if_rmnet.h
index a02f0a3df1d9a..941997df9e088 100644
--- a/include/linux/if_rmnet.h
+++ b/include/linux/if_rmnet.h
@@ -19,21 +19,18 @@ struct rmnet_map_header {
 #define MAP_CMD_FLAG			BIT(7)
 
 struct rmnet_map_dl_csum_trailer {
-	u8  reserved1;
-#if defined(__LITTLE_ENDIAN_BITFIELD)
-	u8  valid:1;
-	u8  reserved2:7;
-#elif defined (__BIG_ENDIAN_BITFIELD)
-	u8  reserved2:7;
-	u8  valid:1;
-#else
-#error	"Please fix <asm/byteorder.h>"
-#endif
+	u8 reserved1;
+	u8 flags;			/* MAP_CSUM_DL_VALID_FLAG */
 	__be16 csum_start_offset;
 	__be16 csum_length;
 	__be16 csum_value;
 } __aligned(1);
 
+/* rmnet_map_dl_csum_trailer flags field:
+ *  VALID:	1 = checksum and length valid; 0 = ignore them
+ */
+#define MAP_CSUM_DL_VALID_FLAG		BIT(0)
+
 struct rmnet_map_ul_csum_header {
 	__be16 csum_start_offset;
 #if defined(__LITTLE_ENDIAN_BITFIELD)
-- 
2.27.0