net: checksum: Move from32to16() to generic header

from32to16() is used by lib/checksum.c and also by
arch/parisc/lib/checksum.c. The next patch will use it in the
bpf_csum_diff helper.

Move from32to16() to the include/net/checksum.h as csum_from32to16() and
remove other implementations.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20241026125339.26459-2-puranjay@kernel.org

diff --git a/arch/parisc/lib/checksum.c b/arch/parisc/lib/checksum.c
index 4818f3db84a5c5be043afc2bd16c756a99eef8dd..59d8c15d81bd09e4ebdf9a72b98caf3ca316e024 100644 (file)
--- a/arch/parisc/lib/checksum.c
+++ b/arch/parisc/lib/checksum.c
@@ -25,15 +25,6 @@
        : "=r"(_t)                      \
        : "r"(_r), "0"(_t));
 
-static inline unsigned short from32to16(unsigned int x)
-{
-       /* 32 bits --> 16 bits + carry */
-       x = (x & 0xffff) + (x >> 16);
-       /* 16 bits + carry --> 16 bits including carry */
-       x = (x & 0xffff) + (x >> 16);
-       return (unsigned short)x;
-}
-
 static inline unsigned int do_csum(const unsigned char * buff, int len)
 {
        int odd, count;
@@ -85,7 +76,7 @@ static inline unsigned int do_csum(const unsigned char * buff, int len)
        }
        if (len & 1)
                result += le16_to_cpu(*buff);
-       result = from32to16(result);
+       result = csum_from32to16(result);
        if (odd)
                result = swab16(result);
 out:
@@ -102,7 +93,7 @@ __wsum csum_partial(const void *buff, int len, __wsum sum)
 {
        unsigned int result = do_csum(buff, len);
        addc(result, sum);
-       return (__force __wsum)from32to16(result);
+       return (__force __wsum)csum_from32to16(result);
 }
 
 EXPORT_SYMBOL(csum_partial);

diff --git a/include/net/checksum.h b/include/net/checksum.h
index 1338cb92c8e72a8f2fc5271d9bbda2d7510dd2ef..243f972267b8d19bfb5f76f12411a1327505fdaf 100644 (file)
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -151,6 +151,12 @@ static inline void csum_replace(__wsum *csum, __wsum old, __wsum new)
        *csum = csum_add(csum_sub(*csum, old), new);
 }
 
+static inline unsigned short csum_from32to16(unsigned int sum)
+{
+       sum += (sum >> 16) | (sum << 16);
+       return (unsigned short)(sum >> 16);
+}
+
 struct sk_buff;
 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
                              __be32 from, __be32 to, bool pseudohdr);

diff --git a/lib/checksum.c b/lib/checksum.c
index 6860d6b05a171707391eace7fd371f7f9aa2291a..025ba546e1ec6eade619c0394417fe8eeb52f438 100644 (file)
--- a/lib/checksum.c
+++ b/lib/checksum.c
@@ -34,15 +34,6 @@
 #include <asm/byteorder.h>
 
 #ifndef do_csum
-static inline unsigned short from32to16(unsigned int x)
-{
-       /* add up 16-bit and 16-bit for 16+c bit */
-       x = (x & 0xffff) + (x >> 16);
-       /* add up carry.. */
-       x = (x & 0xffff) + (x >> 16);
-       return x;
-}
-
 static unsigned int do_csum(const unsigned char *buff, int len)
 {
        int odd;
@@ -90,7 +81,7 @@ static unsigned int do_csum(const unsigned char *buff, int len)
 #else
                result += (*buff << 8);
 #endif
-       result = from32to16(result);
+       result = csum_from32to16(result);
        if (odd)
                result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
 out: