netdev - Re: [PATCH] tcp: don't use __constant_cpu_to

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Message-ID: <20190316142646.GA10815@tigerII.localdomain>
Date:   Sat, 16 Mar 2019 23:26:46 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Stanislav Fomichev <sdf@...ichev.me>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCH] tcp: don't use __constant_cpu_to_be32

On (03/16/19 14:19), Sergey Senozhatsky wrote:
> # define __bpf_ntohs(x)                 __builtin_bswap16(x)
> # define __bpf_htons(x)                 __builtin_bswap16(x)
> 
> So I sort of suspect that what should have been done was that
> __HAVE_BUILTIN_BSWAP16__ ifdef, just like what include/uapi/linux/swab.h
> does.

E.g. use uapi __swab16/__swab32 in selftests/bpf/bpf_endian.h?

-=-=-=-=-=-

 tools/testing/selftests/bpf/bpf_endian.h | 32 ++++++++------------------------
 1 file changed, 8 insertions(+), 24 deletions(-)

diff --git a/tools/testing/selftests/bpf/bpf_endian.h b/tools/testing/selftests/bpf/bpf_endian.h
index b25595ea4a78..68789b4c7ef0 100644
--- a/tools/testing/selftests/bpf/bpf_endian.h
+++ b/tools/testing/selftests/bpf/bpf_endian.h
@@ -20,38 +20,22 @@
  * use different targets.
  */
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-# define __bpf_ntohs(x)			__builtin_bswap16(x)
-# define __bpf_htons(x)			__builtin_bswap16(x)
-# define __bpf_constant_ntohs(x)	___constant_swab16(x)
-# define __bpf_constant_htons(x)	___constant_swab16(x)
-# define __bpf_ntohl(x)			__builtin_bswap32(x)
-# define __bpf_htonl(x)			__builtin_bswap32(x)
-# define __bpf_constant_ntohl(x)	___constant_swab32(x)
-# define __bpf_constant_htonl(x)	___constant_swab32(x)
+# define __bpf_ntohs(x)			__swab16(x)
+# define __bpf_htons(x)			__swab16(x)
+# define __bpf_ntohl(x)			__swab32(x)
+# define __bpf_htonl(x)			__swab32(x)
 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 # define __bpf_ntohs(x)			(x)
 # define __bpf_htons(x)			(x)
-# define __bpf_constant_ntohs(x)	(x)
-# define __bpf_constant_htons(x)	(x)
 # define __bpf_ntohl(x)			(x)
 # define __bpf_htonl(x)			(x)
-# define __bpf_constant_ntohl(x)	(x)
-# define __bpf_constant_htonl(x)	(x)
 #else
 # error "Fix your compiler's __BYTE_ORDER__?!"
 #endif
 
-#define bpf_htons(x)				\
-	(__builtin_constant_p(x) ?		\
-	 __bpf_constant_htons(x) : __bpf_htons(x))
-#define bpf_ntohs(x)				\
-	(__builtin_constant_p(x) ?		\
-	 __bpf_constant_ntohs(x) : __bpf_ntohs(x))
-#define bpf_htonl(x)				\
-	(__builtin_constant_p(x) ?		\
-	 __bpf_constant_htonl(x) : __bpf_htonl(x))
-#define bpf_ntohl(x)				\
-	(__builtin_constant_p(x) ?		\
-	 __bpf_constant_ntohl(x) : __bpf_ntohl(x))
+#define bpf_htons(x)	__bpf_htons((x))
+#define bpf_ntohs(x)	__bpf_ntohs((x))
+#define bpf_htonl(x)	__bpf_htonl((x))
+#define bpf_ntohl(x)	__bpf_ntohl((x))
 
 #endif /* __BPF_ENDIAN__ */