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From: Alex Elder <elder@linaro.org>
To: subashab@codeaurora.org, stranche@codeaurora.org,
	davem@davemloft.net, kuba@kernel.org
Cc: bjorn.andersson@linaro.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH net-next 6/8] net: qualcomm: rmnet: trailer value is a checksum
Date: Sat, 12 Jun 2021 09:37:34 -0500	[thread overview]
Message-ID: <20210612143736.3498712-7-elder@linaro.org> (raw)
In-Reply-To: <20210612143736.3498712-1-elder@linaro.org>

The csum_value field in the rmnet_map_dl_csum_trailer structure is a
"real" Internet checksum.  It is a 16 bit value, in big endian format,
which represents an inverted ones' complement sum over pairs of bytes.

Make that clear by changing its type to __sum16.

This makes a typecast in rmnet_map_ipv4_dl_csum_trailer() and
another in rmnet_map_ipv6_dl_csum_trailer() unnecessary.

Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c | 5 ++---
 include/linux/if_rmnet.h                             | 2 +-
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 033b8ad3d7356..610c8b5a8f46a 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -87,7 +87,7 @@ rmnet_map_ipv4_dl_csum_trailer(struct sk_buff *skb,
 	 * header checksum value; it is already accounted for in the
 	 * checksum value found in the trailer.
 	 */
-	ip_payload_csum = (__force __sum16)~csum_trailer->csum_value;
+	ip_payload_csum = ~csum_trailer->csum_value;
 
 	pseudo_csum = ~csum_tcpudp_magic(ip4h->saddr, ip4h->daddr,
 					 ntohs(ip4h->tot_len) - ip4h->ihl * 4,
@@ -132,8 +132,7 @@ rmnet_map_ipv6_dl_csum_trailer(struct sk_buff *skb,
 	 * checksum computed over the pseudo header.
 	 */
 	ip_header_csum = (__force __be16)ip_fast_csum(ip6h, sizeof(*ip6h) / 4);
-	ip6_payload_csum = ~csum16_sub((__force __sum16)csum_trailer->csum_value,
-				       ip_header_csum);
+	ip6_payload_csum = ~csum16_sub(csum_trailer->csum_value, ip_header_csum);
 
 	length = (ip6h->nexthdr == IPPROTO_UDP) ?
 		 ntohs(((struct udphdr *)txporthdr)->len) :
diff --git a/include/linux/if_rmnet.h b/include/linux/if_rmnet.h
index be17610a981ef..10e7521ecb6cd 100644
--- a/include/linux/if_rmnet.h
+++ b/include/linux/if_rmnet.h
@@ -25,7 +25,7 @@ struct rmnet_map_dl_csum_trailer {
 	u8 flags;			/* MAP_CSUM_DL_VALID_FLAG */
 	__be16 csum_start_offset;
 	__be16 csum_length;
-	__be16 csum_value;
+	__sum16 csum_value;
 } __aligned(1);
 
 /* rmnet_map_dl_csum_trailer flags field:
-- 
2.27.0


  parent reply	other threads:[~2021-06-12 14:37 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-12 14:37 [PATCH net-next 0/8] net: qualcomm: rmnet: MAPv4 download checksum cleanup, part 2 Alex Elder
2021-06-12 14:37 ` [PATCH net-next 1/8] net: qualcomm: rmnet: remove some local variables Alex Elder
2021-06-12 14:37 ` [PATCH net-next 2/8] net: qualcomm: rmnet: rearrange some NOTs Alex Elder
2021-06-12 14:37 ` [PATCH net-next 3/8] net: qualcomm: rmnet: show that an intermediate sum is zero Alex Elder
2021-06-12 14:37 ` [PATCH net-next 4/8] net: qualcomm: rmnet: return earlier for bad checksum Alex Elder
2021-06-12 14:37 ` [PATCH net-next 5/8] net: qualcomm: rmnet: remove unneeded code Alex Elder
2021-06-12 14:37 ` Alex Elder [this message]
2021-06-12 14:37 ` [PATCH net-next 7/8] net: qualcomm: rmnet: drop some unary NOTs Alex Elder
2021-06-12 14:37 ` [PATCH net-next 8/8] net: qualcomm: rmnet: IPv6 payload length is simple Alex Elder

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