diff options
Diffstat (limited to 'net/dccp/ackvec.c')
| -rw-r--r-- | net/dccp/ackvec.c | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c index af976fca407..abaf241c735 100644 --- a/net/dccp/ackvec.c +++ b/net/dccp/ackvec.c @@ -29,7 +29,7 @@ struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority) struct dccp_ackvec *av = kmem_cache_zalloc(dccp_ackvec_slab, priority); if (av != NULL) { - av->av_buf_head = DCCPAV_MAX_ACKVEC_LEN - 1; + av->av_buf_head = av->av_buf_tail = DCCPAV_MAX_ACKVEC_LEN - 1; INIT_LIST_HEAD(&av->av_records); } return av; @@ -72,6 +72,14 @@ int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum) avr->avr_ack_nonce = nonce_sum; avr->avr_ack_runlen = dccp_ackvec_runlen(av->av_buf + av->av_buf_head); /* + * When the buffer overflows, we keep no more than one record. This is + * the simplest way of disambiguating sender-Acks dating from before the + * overflow from sender-Acks which refer to after the overflow; a simple + * solution is preferable here since we are handling an exception. + */ + if (av->av_overflow) + dccp_ackvec_purge_records(av); + /* * Since GSS is incremented for each packet, the list is automatically * arranged in descending order of @ack_seqno. */ @@ -85,6 +93,27 @@ int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum) } /* + * Buffer index and length computation using modulo-buffersize arithmetic. + * Note that, as pointers move from right to left, head is `before' tail. + */ +static inline u16 __ackvec_idx_add(const u16 a, const u16 b) +{ + return (a + b) % DCCPAV_MAX_ACKVEC_LEN; +} + +static inline u16 __ackvec_idx_sub(const u16 a, const u16 b) +{ + return __ackvec_idx_add(a, DCCPAV_MAX_ACKVEC_LEN - b); +} + +u16 dccp_ackvec_buflen(const struct dccp_ackvec *av) +{ + if (unlikely(av->av_overflow)) + return DCCPAV_MAX_ACKVEC_LEN; + return __ackvec_idx_sub(av->av_buf_tail, av->av_buf_head); +} + +/* * If several packets are missing, the HC-Receiver may prefer to enter multiple * bytes with run length 0, rather than a single byte with a larger run length; * this simplifies table updates if one of the missing packets arrives. |