/* * netsniff-ng - the packet sniffing beast * Copyright 2010 Emmanuel Roullit. * Subject to the GPL, version 2. */ #ifndef CSUM_H #define CSUM_H #include #include #include "built_in.h" static inline unsigned short csum(unsigned short *buf, int nwords) { unsigned long sum; for (sum = 0; nwords > 0; nwords--) sum += *buf++; sum = (sum >> 16) + (sum & 0xffff); sum += (sum >> 16); return ~sum; } static inline uint16_t calc_csum(void *addr, size_t len, int ccsum __maybe_unused) { return csum(addr, len >> 1); } static inline uint16_t csum_expected(uint16_t sum, uint16_t computed_sum) { uint32_t shouldbe; shouldbe = sum; shouldbe += ntohs(computed_sum); shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16); shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16); return shouldbe; } /* Taken and modified from tcpdump, Copyright belongs to them! */ struct cksum_vec { const u8 *ptr; int len; }; #define ADDCARRY(x) \ do { if ((x) > 65535) \ (x) -= 65535; \ } while (0) #define REDUCE \ do { \ l_util.l = sum; \ sum = l_util.s[0] + l_util.s[1]; \ ADDCARRY(sum); \ } while (0) static inline u16 __in_cksum(const struct cksum_vec *vec, int veclen) { const u16 *w; int sum = 0, mlen = 0; int byte_swapped = 0; union { u8 c[2]; u16 s; } s_util; union { u16 s[2]; u32 l; } l_util; for (; veclen != 0; vec++, veclen--) { if (vec->len == 0) continue; w = (const u16 *) (void *) vec->ptr; if (mlen == -1) { s_util.c[1] = *(const u8 *) w; sum += s_util.s; w = (const u16 *) (void *) ((const u8 *) w + 1); mlen = vec->len - 1; } else mlen = vec->len; if ((1 & (unsigned long) w) && (mlen > 0)) { REDUCE; sum <<= 8; s_util.c[0] = *(const u8 *) w; w = (const u16 *) (void *) ((const u8 *) w + 1); mlen--; byte_swapped = 1; } while ((mlen -= 32) >= 0) { sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7]; sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11]; sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15]; w += 16; } mlen += 32; while ((mlen -= 8) >= 0) { sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3]; w += 4; } mlen += 8; if (mlen == 0 && byte_swapped == 0) continue; REDUCE; while ((mlen -= 2) >= 0) { sum += *w++; } if (byte_swapped) { REDUCE; sum <<= 8; byte_swapped = 0; if (mlen == -1) { s_util.c[1] = *(const u8 *) w; sum += s_util.s; mlen = 0; } else mlen = -1; } else if (mlen == -1) s_util.c[0] = *(const u8 *) w; } if (mlen == -1) { s_util.c[1] = 0; sum += s_util.s; } REDUCE; return (~sum & 0xffff); } static inline u16 p4_csum(const struct ip *ip, const u8 *data, u16 len, u8 next_proto) { struct cksum_vec vec[2]; struct pseudo_hdr { u32 src; u32 dst; u8 mbz; u8 proto; u16 len; } ph; memset(&ph, 0, sizeof(ph)); ph.len = htons(len); ph.mbz = 0; ph.proto = next_proto; ph.src = ip->ip_src.s_addr; ph.dst = ip->ip_dst.s_addr; vec[0].ptr = (const u8 *) (void *) &ph; vec[0].len = sizeof(ph); vec[1].ptr = data; vec[1].len = len; return __in_cksum(vec, 2); } #endif /* CSUM_H */ 5space:mode:
authorBryan O'Donoghue <bryan.odonoghue@linaro.org>2016-08-02 13:18:30 +0100
committerGreg Kroah-Hartman <gregkh@google.com>2016-08-03 10:59:13 +0200
commit7aa278b771505f8fb85406a891af0b7743710620 (patch)
tree97dfe33bfd4edae9af578f2e0cab3b894939d541
parentb6fc2876a060fdd89f6dd55a4923580983092b0f (diff)
greybus: timesync: Implement a retry mechanism
It's possible the AP could miss an incoming SVC timesync pulse i.e. the AP could have interrupts switched off for long enough that one SVC GPIO strobe ends up over-lapping another one. TimeSync should be able to deal with this type of transitory failure by retrying a failed synchronous TimeSync resync up to 'n' number of times. For this patch 'n' has been set to five, which is a hand-wavy choice that 'feels' right. Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
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