From a3007446e53af07c53bdb4cabad7b3ea60859da4 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Tue, 20 Sep 2016 18:19:13 -0300 Subject: sctp: fix the handling of SACK Gap Ack blocks sctp_acked() is using 32bit arithmetics on 16bits vars, via TSN_lte() macros, which is weird and confusing. Once the offset to ctsn is calculated, all wrapping is already handled and thus to verify the Gap Ack blocks we can just use pure less/big-or-equal than checks. Also, rename gap variable to tsn_offset, so it's more meaningful, as it doesn't point to any gap at all. Even so, I don't think this discrepancy resulted in any practical bug. This patch is a preparation for the next one, which will introduce typecheck() for TSN_lte() macros and would cause a compile error here. Suggested-by: David Laight Reported-by: David Laight Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/sctp/outqueue.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c index 8c3f446d965c..3ec6da8bbb53 100644 --- a/net/sctp/outqueue.c +++ b/net/sctp/outqueue.c @@ -1719,7 +1719,7 @@ static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn) { int i; sctp_sack_variable_t *frags; - __u16 gap; + __u16 tsn_offset, blocks; __u32 ctsn = ntohl(sack->cum_tsn_ack); if (TSN_lte(tsn, ctsn)) @@ -1738,10 +1738,11 @@ static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn) */ frags = sack->variable; - gap = tsn - ctsn; - for (i = 0; i < ntohs(sack->num_gap_ack_blocks); ++i) { - if (TSN_lte(ntohs(frags[i].gab.start), gap) && - TSN_lte(gap, ntohs(frags[i].gab.end))) + blocks = ntohs(sack->num_gap_ack_blocks); + tsn_offset = tsn - ctsn; + for (i = 0; i < blocks; ++i) { + if (tsn_offset >= ntohs(frags[i].gab.start) && + tsn_offset <= ntohs(frags[i].gab.end)) goto pass; } -- cgit v1.2.3-55-g7522 From 182691d0998400f35ad304718024e60feaa864aa Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Tue, 20 Sep 2016 18:19:14 -0300 Subject: 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 -- cgit v1.2.3-55-g7522