netdev - [PATCH 3/8] net: qualcomm: rmnet: use field masks instead of C bit-fields

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Date:   Mon, 20 May 2019 08:53:49 -0500
From:   Alex Elder <elder@...aro.org>
To:     arnd@...db.de, subashab@...eaurora.org, david.brown@...aro.org,
        agross@...nel.org, davem@...emloft.net
Cc:     bjorn.andersson@...aro.org, ilias.apalodimas@...aro.org,
        cpratapa@...eaurora.org, syadagir@...eaurora.org,
        evgreen@...omium.org, benchan@...gle.com, ejcaruso@...gle.com,
        netdev@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/8] net: qualcomm: rmnet: use field masks instead of C bit-fields

Using C bitfields (e.g. int foo : 3) is not portable.  So stop
using them for the command/data flag and the pad length fields in
the rmnet_map structure.  Instead, use the functions defined in
<linux/bitfield.h> along with field mask constants to extract or
assign values within an integral structure member of a known size.

Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c | 5 +++--
 drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h      | 8 +++++---
 drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c | 5 ++++-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
index 4c1b62b72504..5fff6c78ecd5 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c
@@ -13,6 +13,7 @@
  *
  */
 
+#include <linux/bitfield.h>
 #include <linux/netdevice.h>
 #include <linux/netdev_features.h>
 #include <linux/if_arp.h>
@@ -70,7 +71,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
 	u16 len, pad;
 	u8 mux_id;
 
-	if (map_header->cd_bit) {
+	if (u8_get_bits(map_header->cmd_pad_len, RMNET_MAP_CMD_FMASK)) {
 		if (port->data_format & RMNET_FLAGS_INGRESS_MAP_COMMANDS)
 			return rmnet_map_command(skb, port);
 
@@ -78,7 +79,7 @@ __rmnet_map_ingress_handler(struct sk_buff *skb,
 	}
 
 	mux_id = map_header->mux_id;
-	pad = map_header->pad_len;
+	pad = u8_get_bits(map_header->cmd_pad_len, RMNET_MAP_PAD_LEN_FMASK);
 	len = ntohs(map_header->pkt_len) - pad;
 
 	if (mux_id >= RMNET_MAX_LOGICAL_EP)
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
index a30a7b405a11..a56209645c81 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map.h
@@ -40,13 +40,15 @@ enum rmnet_map_commands {
 };
 
 struct rmnet_map_header {
-	u8  cd_bit:1;
-	u8  reserved_bit:1;
-	u8  pad_len:6;
+	u8  cmd_pad_len;	/* RMNET_MAP_* */
 	u8  mux_id;
 	__be16 pkt_len;
 }  __aligned(1);
 
+#define RMNET_MAP_CMD_FMASK		GENMASK(0, 0)   /* 0: data; 1: cmd */
+#define RMNET_MAP_RESERVED_FMASK	GENMASK(1, 1)
+#define RMNET_MAP_PAD_LEN_FMASK		GENMASK(7, 2)
+
 struct rmnet_map_dl_csum_trailer {
 	u8  reserved1;
 	u8  valid:1;
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
index 498f20ba1826..10d2d582a9ce 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_map_data.c
@@ -13,6 +13,7 @@
  *
  */
 
+#include <linux/bitfield.h>
 #include <linux/netdevice.h>
 #include <linux/ip.h>
 #include <linux/ipv6.h>
@@ -301,7 +302,9 @@ struct rmnet_map_header *rmnet_map_add_map_header(struct sk_buff *skb,
 
 done:
 	map_header->pkt_len = htons(map_datalen + padding);
-	map_header->pad_len = padding & 0x3F;
+	/* This is a data packet, so cmd field is 0 */
+	map_header->cmd_pad_len =
+			u8_encode_bits(padding, RMNET_MAP_PAD_LEN_FMASK);
 
 	return map_header;
 }
-- 
2.20.1