netdev - [PATCH] net: amd-xgbe: fix clang -Wformat warning

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Message-Id: <20220607191119.20686-1-jstitt007@gmail.com>
Date:   Tue,  7 Jun 2022 12:11:19 -0700
From:   Justin Stitt <jstitt007@...il.com>
To:     Tom Lendacky <thomas.lendacky@....com>
Cc:     llvm@...ts.linux.dev, Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <nathan@...nel.org>, netdev@...r.kernel.org,
        Justin Stitt <jstitt007@...il.com>
Subject: [PATCH] net: amd-xgbe: fix clang -Wformat warning

see warning:
| drivers/net/ethernet/amd/xgbe/xgbe-drv.c:2787:43: warning: format specifies
| type 'unsigned short' but the argument has type 'int' [-Wformat]
|        netdev_dbg(netdev, "Protocol: %#06hx\n", ntohs(eth->h_proto));
|                                      ~~~~~~     ^~~~~~~~~~~~~~~~~~~

Variadic functions (printf-like) undergo default argument promotion.
Documentation/core-api/printk-formats.rst specifically recommends
using the promoted-to-type's format flag.

Also, as per C11 6.3.1.1:
(https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf)
`If an int can represent all values of the original type ..., the
value is converted to an int; otherwise, it is converted to an
unsigned int. These are called the integer promotions.`

Since the argument is a u16 it will get promoted to an int and thus it is
most accurate to use the %x format specifier here. It should be noted that the
`#06` formatting sugar does not alter the promotion rules.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Signed-off-by: Justin Stitt <jstitt007@...il.com>
---
 drivers/net/ethernet/amd/xgbe/xgbe-drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index a3593290886f..4d46780fad13 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -2784,7 +2784,7 @@ void xgbe_print_pkt(struct net_device *netdev, struct sk_buff *skb, bool tx_rx)
 
 	netdev_dbg(netdev, "Dst MAC addr: %pM\n", eth->h_dest);
 	netdev_dbg(netdev, "Src MAC addr: %pM\n", eth->h_source);
-	netdev_dbg(netdev, "Protocol: %#06hx\n", ntohs(eth->h_proto));
+	netdev_dbg(netdev, "Protocol: %#06x\n", ntohs(eth->h_proto));
 
 	for (i = 0; i < skb->len; i += 32) {
 		unsigned int len = min(skb->len - i, 32U);
-- 
2.30.2