From 182691d0998400f35ad304718024e60feaa864aa Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Tue, 20 Sep 2016 18:19:14 -0300 Subject: [PATCH] sctp: improve how SSN, TSN and ASCONF serial are compared 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 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 1f17: 39 f8 cmp %edi,%eax 1f19: 78 21 js 1f3c 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 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 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 Signed-off-by: David S. Miller --- 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 bafe2a0ab908..ca6c971dd74a 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 -- 2.20.1