Make it similar to time_before() macros:
- easier to understand
- make use of typecheck() to avoid working on unexpected variable types
(made the issue on previous patch visible)
- for _[lg]te versions, slighly faster, as the compiler used to generate
a sequence of cmp/je/cmp/js instructions and now it's sub/test/jle
(for _lte):
Before, for sctp_outq_sack:
if (primary->cacc.changeover_active) {
1f01: 80 b9 84 02 00 00 00 cmpb $0x0,0x284(%rcx)
1f08: 74 6e je 1f78 <sctp_outq_sack+0xe8>
u8 clear_cycling = 0;
if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1f0a: 8b 81 80 02 00 00 mov 0x280(%rcx),%eax
return ((s) - (t)) & TSN_SIGN_BIT;
}
static inline int TSN_lte(__u32 s, __u32 t)
{
return ((s) == (t)) || (((s) - (t)) & TSN_SIGN_BIT);
1f10: 8b 7d bc mov -0x44(%rbp),%edi
1f13: 39 c7 cmp %eax,%edi
1f15: 74 25 je 1f3c <sctp_outq_sack+0xac>
1f17: 39 f8 cmp %edi,%eax
1f19: 78 21 js 1f3c <sctp_outq_sack+0xac>
primary->cacc.changeover_active = 0;
After:
if (primary->cacc.changeover_active) {
1ee7: 80 b9 84 02 00 00 00 cmpb $0x0,0x284(%rcx)
1eee: 74 73 je 1f63 <sctp_outq_sack+0xf3>
u8 clear_cycling = 0;
if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1ef0: 8b 81 80 02 00 00 mov 0x280(%rcx),%eax
1ef6: 2b 45 b4 sub -0x4c(%rbp),%eax
1ef9: 85 c0 test %eax,%eax
1efb: 7e 26 jle 1f23 <sctp_outq_sack+0xb3>
primary->cacc.changeover_active = 0;
*_lt() generated pretty much the same code.
Tested with gcc (GCC) 6.1.1 20160621.
This patch also removes SSN_lte as it is not used and cleanups some
comments.
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leit...@gmail.com>
---
include/net/sctp/sm.h | 94 ++++++++++-----------------------------------------
1 file changed, 18 insertions(+), 76 deletions(-)
diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h
index
bafe2a0ab9085f24e17038516c55c00cfddd02f4..ca6c971dd74aede829d4512ddf71006520c78f47
100644
--- a/include/net/sctp/sm.h
+++ b/include/net/sctp/sm.h
@@ -307,85 +307,27 @@ static inline __u16 sctp_data_size(struct sctp_chunk
*chunk)
}
/* Compare two TSNs */
+#define TSN_lt(a,b) \
+ (typecheck(__u32, a) && \
+ typecheck(__u32, b) && \
+ ((__s32)((a) - (b)) < 0))
-/* RFC 1982 - Serial Number Arithmetic
- *
- * 2. Comparison
- * Then, s1 is said to be equal to s2 if and only if i1 is equal to i2,
- * in all other cases, s1 is not equal to s2.
- *
- * s1 is said to be less than s2 if, and only if, s1 is not equal to s2,
- * and
- *
- * (i1 < i2 and i2 - i1 < 2^(SERIAL_BITS - 1)) or
- * (i1 > i2 and i1 - i2 > 2^(SERIAL_BITS - 1))
- *
- * s1 is said to be greater than s2 if, and only if, s1 is not equal to
- * s2, and
- *
- * (i1 < i2 and i2 - i1 > 2^(SERIAL_BITS - 1)) or
- * (i1 > i2 and i1 - i2 < 2^(SERIAL_BITS - 1))
- */
-
-/*
- * RFC 2960
- * 1.6 Serial Number Arithmetic
- *
- * Comparisons and arithmetic on TSNs in this document SHOULD use Serial
- * Number Arithmetic as defined in [RFC1982] where SERIAL_BITS = 32.
- */
-
-enum {
- TSN_SIGN_BIT = (1<<31)
-};
-
-static inline int TSN_lt(__u32 s, __u32 t)
-{
- return ((s) - (t)) & TSN_SIGN_BIT;
-}
-
-static inline int TSN_lte(__u32 s, __u32 t)
-{
- return ((s) == (t)) || (((s) - (t)) & TSN_SIGN_BIT);
-}
+#define TSN_lte(a,b) \
+ (typecheck(__u32, a) && \
+ typecheck(__u32, b) && \
+ ((__s32)((a) - (b)) <= 0))
/* Compare two SSNs */
-
-/*
- * RFC 2960
- * 1.6 Serial Number Arithmetic
- *
- * Comparisons and arithmetic on Stream Sequence Numbers in this document
- * SHOULD use Serial Number Arithmetic as defined in [RFC1982] where
- * SERIAL_BITS = 16.
- */
-enum {
- SSN_SIGN_BIT = (1<<15)
-};
-
-static inline int SSN_lt(__u16 s, __u16 t)
-{
- return ((s) - (t)) & SSN_SIGN_BIT;
-}
-
-static inline int SSN_lte(__u16 s, __u16 t)
-{
- return ((s) == (t)) || (((s) - (t)) & SSN_SIGN_BIT);
-}
-
-/*
- * ADDIP 3.1.1
- * The valid range of Serial Number is from 0 to 4294967295 (2**32 - 1). Serial
- * Numbers wrap back to 0 after reaching 4294967295.
- */
-enum {
- ADDIP_SERIAL_SIGN_BIT = (1<<31)
-};
-
-static inline int ADDIP_SERIAL_gte(__u32 s, __u32 t)
-{
- return ((s) == (t)) || (((t) - (s)) & ADDIP_SERIAL_SIGN_BIT);
-}
+#define SSN_lt(a,b) \
+ (typecheck(__u16, a) && \
+ typecheck(__u16, b) && \
+ ((__s16)((a) - (b)) < 0))
+
+/* ADDIP 3.1.1 */
+#define ADDIP_SERIAL_gte(a,b) \
+ (typecheck(__u32, a) && \
+ typecheck(__u32, b) && \
+ ((__s32)((b) - (a)) <= 0))
/* Check VTAG of the packet matches the sender's own tag. */
static inline int
--
2.7.4
