From 5753fdfe8bd8e9a2ff9e5af19b0ffc78bfcd502a Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 14 Nov 2010 17:25:11 +0100 Subject: dccp ccid-2: Algorithm to update buffer state This provides a routine to consistently update the buffer state when the peer acknowledges receipt of Ack Vectors; updating state in the list of Ack Vectors as well as in the circular buffer. While based on RFC 4340, several additional (and necessary) precautions were added to protect the consistency of the buffer state. These additions are essential, since analysis and experience showed that the basic algorithm was insufficient for this task (which lead to problems that were hard to debug). The algorithm now * deals with HC-sender acknowledging to HC-receiver and vice versa, * keeps track of the last unacknowledged but received seqno in tail_ackno, * has special cases to reset the overflow condition when appropriate, * is protected against receiving older information (would mess up buffer state). Signed-off-by: Gerrit Renker --- net/dccp/ackvec.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) (limited to 'net/dccp/ackvec.c') diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c index abaf241c735..e9a0f66e4af 100644 --- a/net/dccp/ackvec.c +++ b/net/dccp/ackvec.c @@ -92,6 +92,24 @@ int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum) return 0; } +static struct dccp_ackvec_record *dccp_ackvec_lookup(struct list_head *av_list, + const u64 ackno) +{ + struct dccp_ackvec_record *avr; + /* + * Exploit that records are inserted in descending order of sequence + * number, start with the oldest record first. If @ackno is `before' + * the earliest ack_ackno, the packet is too old to be considered. + */ + list_for_each_entry_reverse(avr, av_list, avr_node) { + if (avr->avr_ack_seqno == ackno) + return avr; + if (before48(ackno, avr->avr_ack_seqno)) + break; + } + return NULL; +} + /* * Buffer index and length computation using modulo-buffersize arithmetic. * Note that, as pointers move from right to left, head is `before' tail. @@ -356,6 +374,76 @@ int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb, return 0; } +/** + * dccp_ackvec_clear_state - Perform house-keeping / garbage-collection + * This routine is called when the peer acknowledges the receipt of Ack Vectors + * up to and including @ackno. While based on on section A.3 of RFC 4340, here + * are additional precautions to prevent corrupted buffer state. In particular, + * we use tail_ackno to identify outdated records; it always marks the earliest + * packet of group (2) in 11.4.2. + */ +void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno) + { + struct dccp_ackvec_record *avr, *next; + u8 runlen_now, eff_runlen; + s64 delta; + + avr = dccp_ackvec_lookup(&av->av_records, ackno); + if (avr == NULL) + return; + /* + * Deal with outdated acknowledgments: this arises when e.g. there are + * several old records and the acks from the peer come in slowly. In + * that case we may still have records that pre-date tail_ackno. + */ + delta = dccp_delta_seqno(av->av_tail_ackno, avr->avr_ack_ackno); + if (delta < 0) + goto free_records; + /* + * Deal with overlapping Ack Vectors: don't subtract more than the + * number of packets between tail_ackno and ack_ackno. + */ + eff_runlen = delta < avr->avr_ack_runlen ? delta : avr->avr_ack_runlen; + + runlen_now = dccp_ackvec_runlen(av->av_buf + avr->avr_ack_ptr); + /* + * The run length of Ack Vector cells does not decrease over time. If + * the run length is the same as at the time the Ack Vector was sent, we + * free the ack_ptr cell. That cell can however not be freed if the run + * length has increased: in this case we need to move the tail pointer + * backwards (towards higher indices), to its next-oldest neighbour. + */ + if (runlen_now > eff_runlen) { + + av->av_buf[avr->avr_ack_ptr] -= eff_runlen + 1; + av->av_buf_tail = __ackvec_idx_add(avr->avr_ack_ptr, 1); + + /* This move may not have cleared the overflow flag. */ + if (av->av_overflow) + av->av_overflow = (av->av_buf_head == av->av_buf_tail); + } else { + av->av_buf_tail = avr->avr_ack_ptr; + /* + * We have made sure that avr points to a valid cell within the + * buffer. This cell is either older than head, or equals head + * (empty buffer): in both cases we no longer have any overflow. + */ + av->av_overflow = 0; + } + + /* + * The peer has acknowledged up to and including ack_ackno. Hence the + * first packet in group (2) of 11.4.2 is the successor of ack_ackno. + */ + av->av_tail_ackno = ADD48(avr->avr_ack_ackno, 1); + +free_records: + list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) { + list_del(&avr->avr_node); + kmem_cache_free(dccp_ackvec_record_slab, avr); + } +} + int __init dccp_ackvec_init(void) { dccp_ackvec_slab = kmem_cache_create("dccp_ackvec", -- cgit v1.2.3 From 3802408644515e29fb723d51a5317301b212cf3a Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 14 Nov 2010 17:25:23 +0100 Subject: dccp ccid-2: Update code for the Ack Vector input/registration routine This patch updates the code which registers new packets as received, using the new circular buffer interface. It contributes a new algorithm which * supports both tail/head pointers and buffer wrap-around and * deals with overflow (head/tail move in lock-step). Signed-off-by: Gerrit Renker --- net/dccp/ackvec.c | 150 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ net/dccp/ackvec.h | 4 ++ 2 files changed, 154 insertions(+) (limited to 'net/dccp/ackvec.c') diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c index e9a0f66e4af..f7e647e608b 100644 --- a/net/dccp/ackvec.c +++ b/net/dccp/ackvec.c @@ -131,6 +131,156 @@ u16 dccp_ackvec_buflen(const struct dccp_ackvec *av) return __ackvec_idx_sub(av->av_buf_tail, av->av_buf_head); } +/** + * dccp_ackvec_update_old - Update previous state as per RFC 4340, 11.4.1 + * @av: non-empty buffer to update + * @distance: negative or zero distance of @seqno from buf_ackno downward + * @seqno: the (old) sequence number whose record is to be updated + * @state: state in which packet carrying @seqno was received + */ +static void dccp_ackvec_update_old(struct dccp_ackvec *av, s64 distance, + u64 seqno, enum dccp_ackvec_states state) +{ + u16 ptr = av->av_buf_head; + + BUG_ON(distance > 0); + if (unlikely(dccp_ackvec_is_empty(av))) + return; + + do { + u8 runlen = dccp_ackvec_runlen(av->av_buf + ptr); + + if (distance + runlen >= 0) { + /* + * Only update the state if packet has not been received + * yet. This is OK as per the second table in RFC 4340, + * 11.4.1; i.e. here we are using the following table: + * RECEIVED + * 0 1 3 + * S +---+---+---+ + * T 0 | 0 | 0 | 0 | + * O +---+---+---+ + * R 1 | 1 | 1 | 1 | + * E +---+---+---+ + * D 3 | 0 | 1 | 3 | + * +---+---+---+ + * The "Not Received" state was set by reserve_seats(). + */ + if (av->av_buf[ptr] == DCCPAV_NOT_RECEIVED) + av->av_buf[ptr] = state; + else + dccp_pr_debug("Not changing %llu state to %u\n", + (unsigned long long)seqno, state); + break; + } + + distance += runlen + 1; + ptr = __ackvec_idx_add(ptr, 1); + + } while (ptr != av->av_buf_tail); +} + +/* Mark @num entries after buf_head as "Not yet received". */ +static void dccp_ackvec_reserve_seats(struct dccp_ackvec *av, u16 num) +{ + u16 start = __ackvec_idx_add(av->av_buf_head, 1), + len = DCCPAV_MAX_ACKVEC_LEN - start; + + /* check for buffer wrap-around */ + if (num > len) { + memset(av->av_buf + start, DCCPAV_NOT_RECEIVED, len); + start = 0; + num -= len; + } + if (num) + memset(av->av_buf + start, DCCPAV_NOT_RECEIVED, num); +} + +/** + * dccp_ackvec_add_new - Record one or more new entries in Ack Vector buffer + * @av: container of buffer to update (can be empty or non-empty) + * @num_packets: number of packets to register (must be >= 1) + * @seqno: sequence number of the first packet in @num_packets + * @state: state in which packet carrying @seqno was received + */ +static void dccp_ackvec_add_new(struct dccp_ackvec *av, u32 num_packets, + u64 seqno, enum dccp_ackvec_states state) +{ + u32 num_cells = num_packets; + + if (num_packets > DCCPAV_BURST_THRESH) { + u32 lost_packets = num_packets - 1; + + DCCP_WARN("Warning: large burst loss (%u)\n", lost_packets); + /* + * We received 1 packet and have a loss of size "num_packets-1" + * which we squeeze into num_cells-1 rather than reserving an + * entire byte for each lost packet. + * The reason is that the vector grows in O(burst_length); when + * it grows too large there will no room left for the payload. + * This is a trade-off: if a few packets out of the burst show + * up later, their state will not be changed; it is simply too + * costly to reshuffle/reallocate/copy the buffer each time. + * Should such problems persist, we will need to switch to a + * different underlying data structure. + */ + for (num_packets = num_cells = 1; lost_packets; ++num_cells) { + u8 len = min(lost_packets, (u32)DCCPAV_MAX_RUNLEN); + + av->av_buf_head = __ackvec_idx_sub(av->av_buf_head, 1); + av->av_buf[av->av_buf_head] = DCCPAV_NOT_RECEIVED | len; + + lost_packets -= len; + } + } + + if (num_cells + dccp_ackvec_buflen(av) >= DCCPAV_MAX_ACKVEC_LEN) { + DCCP_CRIT("Ack Vector buffer overflow: dropping old entries\n"); + av->av_overflow = true; + } + + av->av_buf_head = __ackvec_idx_sub(av->av_buf_head, num_packets); + if (av->av_overflow) + av->av_buf_tail = av->av_buf_head; + + av->av_buf[av->av_buf_head] = state; + av->av_buf_ackno = seqno; + + if (num_packets > 1) + dccp_ackvec_reserve_seats(av, num_packets - 1); +} + +/** + * dccp_ackvec_input - Register incoming packet in the buffer + */ +void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb) +{ + u64 seqno = DCCP_SKB_CB(skb)->dccpd_seq; + enum dccp_ackvec_states state = DCCPAV_RECEIVED; + + if (dccp_ackvec_is_empty(av)) { + dccp_ackvec_add_new(av, 1, seqno, state); + av->av_tail_ackno = seqno; + + } else { + s64 num_packets = dccp_delta_seqno(av->av_buf_ackno, seqno); + u8 *current_head = av->av_buf + av->av_buf_head; + + if (num_packets == 1 && + dccp_ackvec_state(current_head) == state && + dccp_ackvec_runlen(current_head) < DCCPAV_MAX_RUNLEN) { + + *current_head += 1; + av->av_buf_ackno = seqno; + + } else if (num_packets > 0) { + dccp_ackvec_add_new(av, num_packets, seqno, state); + } else { + dccp_ackvec_update_old(av, num_packets, seqno, state); + } + } +} + /* * 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; diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h index 3f7008187b8..21c4212d1be 100644 --- a/net/dccp/ackvec.h +++ b/net/dccp/ackvec.h @@ -29,6 +29,9 @@ /* Estimated minimum average Ack Vector length - used for updating MPS */ #define DCCPAV_MIN_OPTLEN 16 +/* Threshold for coping with large bursts of losses */ +#define DCCPAV_BURST_THRESH (DCCPAV_MAX_ACKVEC_LEN / 8) + enum dccp_ackvec_states { DCCPAV_RECEIVED = 0x00, DCCPAV_ECN_MARKED = 0x40, @@ -116,6 +119,7 @@ extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb, u64 *ackno, const u8 opt, const u8 *value, const u8 len); +extern void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb); extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum); extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno); extern u16 dccp_ackvec_buflen(const struct dccp_ackvec *av); -- cgit v1.2.3 From 52394eecec4e6fa677a61af26f0bd35de665344e Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 14 Nov 2010 17:26:02 +0100 Subject: dccp ccid-2: Remove old infrastructure This removes * functions for which updates have been provided in the preceding patches and * the @av_vec_len field - it is no longer necessary since the buffer length is now always computed dynamically. Signed-off-by: Gerrit Renker --- net/dccp/ackvec.c | 251 ------------------------------------------------------ net/dccp/ackvec.h | 14 --- 2 files changed, 265 deletions(-) (limited to 'net/dccp/ackvec.c') diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c index f7e647e608b..66b8a51300c 100644 --- a/net/dccp/ackvec.c +++ b/net/dccp/ackvec.c @@ -9,18 +9,10 @@ * under the terms of the GNU General Public License as published by the * Free Software Foundation; version 2 of the License; */ - -#include "ackvec.h" #include "dccp.h" - -#include -#include #include -#include #include -#include - static struct kmem_cache *dccp_ackvec_slab; static struct kmem_cache *dccp_ackvec_record_slab; @@ -281,249 +273,6 @@ void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb) } } -/* - * 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. - */ -static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av, - const unsigned int packets, - const unsigned char state) -{ - long gap; - long new_head; - - if (av->av_vec_len + packets > DCCPAV_MAX_ACKVEC_LEN) - return -ENOBUFS; - - gap = packets - 1; - new_head = av->av_buf_head - packets; - - if (new_head < 0) { - if (gap > 0) { - memset(av->av_buf, DCCPAV_NOT_RECEIVED, - gap + new_head + 1); - gap = -new_head; - } - new_head += DCCPAV_MAX_ACKVEC_LEN; - } - - av->av_buf_head = new_head; - - if (gap > 0) - memset(av->av_buf + av->av_buf_head + 1, - DCCPAV_NOT_RECEIVED, gap); - - av->av_buf[av->av_buf_head] = state; - av->av_vec_len += packets; - return 0; -} - -/* - * Implements the RFC 4340, Appendix A - */ -int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk, - const u64 ackno, const u8 state) -{ - u8 *cur_head = av->av_buf + av->av_buf_head, - *buf_end = av->av_buf + DCCPAV_MAX_ACKVEC_LEN; - /* - * Check at the right places if the buffer is full, if it is, tell the - * caller to start dropping packets till the HC-Sender acks our ACK - * vectors, when we will free up space in av_buf. - * - * We may well decide to do buffer compression, etc, but for now lets - * just drop. - * - * From Appendix A.1.1 (`New Packets'): - * - * Of course, the circular buffer may overflow, either when the - * HC-Sender is sending data at a very high rate, when the - * HC-Receiver's acknowledgements are not reaching the HC-Sender, - * or when the HC-Sender is forgetting to acknowledge those acks - * (so the HC-Receiver is unable to clean up old state). In this - * case, the HC-Receiver should either compress the buffer (by - * increasing run lengths when possible), transfer its state to - * a larger buffer, or, as a last resort, drop all received - * packets, without processing them whatsoever, until its buffer - * shrinks again. - */ - - /* See if this is the first ackno being inserted */ - if (av->av_vec_len == 0) { - *cur_head = state; - av->av_vec_len = 1; - } else if (after48(ackno, av->av_buf_ackno)) { - const u64 delta = dccp_delta_seqno(av->av_buf_ackno, ackno); - - /* - * Look if the state of this packet is the same as the - * previous ackno and if so if we can bump the head len. - */ - if (delta == 1 && dccp_ackvec_state(cur_head) == state && - dccp_ackvec_runlen(cur_head) < DCCPAV_MAX_RUNLEN) - *cur_head += 1; - else if (dccp_ackvec_set_buf_head_state(av, delta, state)) - return -ENOBUFS; - } else { - /* - * A.1.2. Old Packets - * - * When a packet with Sequence Number S <= buf_ackno - * arrives, the HC-Receiver will scan the table for - * the byte corresponding to S. (Indexing structures - * could reduce the complexity of this scan.) - */ - u64 delta = dccp_delta_seqno(ackno, av->av_buf_ackno); - - while (1) { - const u8 len = dccp_ackvec_runlen(cur_head); - /* - * valid packets not yet in av_buf have a reserved - * entry, with a len equal to 0. - */ - if (*cur_head == DCCPAV_NOT_RECEIVED && delta == 0) { - dccp_pr_debug("Found %llu reserved seat!\n", - (unsigned long long)ackno); - *cur_head = state; - goto out; - } - /* len == 0 means one packet */ - if (delta < len + 1) - goto out_duplicate; - - delta -= len + 1; - if (++cur_head == buf_end) - cur_head = av->av_buf; - } - } - - av->av_buf_ackno = ackno; -out: - return 0; - -out_duplicate: - /* Duplicate packet */ - dccp_pr_debug("Received a dup or already considered lost " - "packet: %llu\n", (unsigned long long)ackno); - return -EILSEQ; -} - -static void dccp_ackvec_throw_record(struct dccp_ackvec *av, - struct dccp_ackvec_record *avr) -{ - struct dccp_ackvec_record *next; - - /* sort out vector length */ - if (av->av_buf_head <= avr->avr_ack_ptr) - av->av_vec_len = avr->avr_ack_ptr - av->av_buf_head; - else - av->av_vec_len = DCCPAV_MAX_ACKVEC_LEN - 1 - - av->av_buf_head + avr->avr_ack_ptr; - - /* free records */ - list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) { - list_del(&avr->avr_node); - kmem_cache_free(dccp_ackvec_record_slab, avr); - } -} - -void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk, - const u64 ackno) -{ - struct dccp_ackvec_record *avr; - - /* - * If we traverse backwards, it should be faster when we have large - * windows. We will be receiving ACKs for stuff we sent a while back - * -sorbo. - */ - list_for_each_entry_reverse(avr, &av->av_records, avr_node) { - if (ackno == avr->avr_ack_seqno) { - dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, " - "ack_ackno=%llu, ACKED!\n", - dccp_role(sk), avr->avr_ack_runlen, - (unsigned long long)avr->avr_ack_seqno, - (unsigned long long)avr->avr_ack_ackno); - dccp_ackvec_throw_record(av, avr); - break; - } else if (avr->avr_ack_seqno > ackno) - break; /* old news */ - } -} - -static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av, - struct sock *sk, u64 *ackno, - const unsigned char len, - const unsigned char *vector) -{ - unsigned char i; - struct dccp_ackvec_record *avr; - - /* Check if we actually sent an ACK vector */ - if (list_empty(&av->av_records)) - return; - - i = len; - /* - * XXX - * I think it might be more efficient to work backwards. See comment on - * rcv_ackno. -sorbo. - */ - avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node); - while (i--) { - const u8 rl = dccp_ackvec_runlen(vector); - u64 ackno_end_rl; - - dccp_set_seqno(&ackno_end_rl, *ackno - rl); - - /* - * If our AVR sequence number is greater than the ack, go - * forward in the AVR list until it is not so. - */ - list_for_each_entry_from(avr, &av->av_records, avr_node) { - if (!after48(avr->avr_ack_seqno, *ackno)) - goto found; - } - /* End of the av_records list, not found, exit */ - break; -found: - if (between48(avr->avr_ack_seqno, ackno_end_rl, *ackno)) { - if (dccp_ackvec_state(vector) != DCCPAV_NOT_RECEIVED) { - dccp_pr_debug("%s ACK vector 0, len=%d, " - "ack_seqno=%llu, ack_ackno=%llu, " - "ACKED!\n", - dccp_role(sk), len, - (unsigned long long) - avr->avr_ack_seqno, - (unsigned long long) - avr->avr_ack_ackno); - dccp_ackvec_throw_record(av, avr); - break; - } - /* - * If it wasn't received, continue scanning... we might - * find another one. - */ - } - - dccp_set_seqno(ackno, ackno_end_rl - 1); - ++vector; - } -} - -int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb, - u64 *ackno, const u8 opt, const u8 *value, const u8 len) -{ - if (len > DCCP_SINGLE_OPT_MAXLEN) - return -1; - - /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */ - dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk, - ackno, len, value); - return 0; -} - /** * dccp_ackvec_clear_state - Perform house-keeping / garbage-collection * This routine is called when the peer acknowledges the receipt of Ack Vectors diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h index 21c4212d1be..e19b8d5ee05 100644 --- a/net/dccp/ackvec.h +++ b/net/dccp/ackvec.h @@ -64,7 +64,6 @@ static inline u8 dccp_ackvec_state(const u8 *cell) * %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf * @av_overflow: if 1 then buf_head == buf_tail indicates buffer wraparound * @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously) - * @av_veclen: length of the live portion of @av_buf */ struct dccp_ackvec { u8 av_buf[DCCPAV_MAX_ACKVEC_LEN]; @@ -75,7 +74,6 @@ struct dccp_ackvec { bool av_buf_nonce[DCCPAV_NUM_ACKVECS]; u8 av_overflow:1; struct list_head av_records; - u16 av_vec_len; }; /** struct dccp_ackvec_record - Records information about sent Ack Vectors @@ -101,24 +99,12 @@ struct dccp_ackvec_record { u8 avr_ack_nonce:1; }; -struct sock; -struct sk_buff; - extern int dccp_ackvec_init(void); extern void dccp_ackvec_exit(void); extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority); extern void dccp_ackvec_free(struct dccp_ackvec *av); -extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk, - const u64 ackno, const u8 state); - -extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, - struct sock *sk, const u64 ackno); -extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb, - u64 *ackno, const u8 opt, - const u8 *value, const u8 len); - extern void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb); extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum); extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno); -- cgit v1.2.3 From 7e87fe84303cc54ecf3c7b688cb08ca24322a41d Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 14 Nov 2010 17:26:13 +0100 Subject: dccp ccid-2: Separate option parsing from CCID processing This patch replaces an almost identical replication of code: large parts of dccp_parse_options() re-appeared as ccid2_ackvector() in ccid2.c. Apart from the duplication, this caused two more problems: 1. CCIDs should not need to be concerned with parsing header options; 2. one can not assume that Ack Vectors appear as a contiguous area within an skb, it is legal to insert other options and/or padding in between. The current code would throw an error and stop reading in such a case. Since Ack Vectors provide CCID-specific information, they are now processed by the CCID directly, separating this functionality from the main DCCP code. Signed-off-by: Gerrit Renker --- net/dccp/ackvec.c | 28 +++++++++++ net/dccp/ackvec.h | 19 +++++++ net/dccp/ccids/ccid2.c | 134 +++++++++++++++---------------------------------- net/dccp/ccids/ccid2.h | 2 + net/dccp/options.c | 17 ++++--- 5 files changed, 100 insertions(+), 100 deletions(-) (limited to 'net/dccp/ackvec.c') diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c index 66b8a51300c..41819848bdd 100644 --- a/net/dccp/ackvec.c +++ b/net/dccp/ackvec.c @@ -343,6 +343,34 @@ free_records: } } +/* + * Routines to keep track of Ack Vectors received in an skb + */ +int dccp_ackvec_parsed_add(struct list_head *head, u8 *vec, u8 len, u8 nonce) +{ + struct dccp_ackvec_parsed *new = kmalloc(sizeof(*new), GFP_ATOMIC); + + if (new == NULL) + return -ENOBUFS; + new->vec = vec; + new->len = len; + new->nonce = nonce; + + list_add_tail(&new->node, head); + return 0; +} +EXPORT_SYMBOL_GPL(dccp_ackvec_parsed_add); + +void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks) +{ + struct dccp_ackvec_parsed *cur, *next; + + list_for_each_entry_safe(cur, next, parsed_chunks, node) + kfree(cur); + INIT_LIST_HEAD(parsed_chunks); +} +EXPORT_SYMBOL_GPL(dccp_ackvec_parsed_cleanup); + int __init dccp_ackvec_init(void) { dccp_ackvec_slab = kmem_cache_create("dccp_ackvec", diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h index e19b8d5ee05..e2ab0627a5f 100644 --- a/net/dccp/ackvec.h +++ b/net/dccp/ackvec.h @@ -114,4 +114,23 @@ static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av) { return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail; } + +/** + * struct dccp_ackvec_parsed - Record offsets of Ack Vectors in skb + * @vec: start of vector (offset into skb) + * @len: length of @vec + * @nonce: whether @vec had an ECN nonce of 0 or 1 + * @node: FIFO - arranged in descending order of ack_ackno + * This structure is used by CCIDs to access Ack Vectors in a received skb. + */ +struct dccp_ackvec_parsed { + u8 *vec, + len, + nonce:1; + struct list_head node; +}; + +extern int dccp_ackvec_parsed_add(struct list_head *head, + u8 *vec, u8 len, u8 nonce); +extern void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks); #endif /* _ACKVEC_H */ diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c index cb1b4a0d187..e96d5e81003 100644 --- a/net/dccp/ccids/ccid2.c +++ b/net/dccp/ccids/ccid2.c @@ -246,68 +246,6 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len) #endif } -/* XXX Lame code duplication! - * returns -1 if none was found. - * else returns the next offset to use in the function call. - */ -static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset, - unsigned char **vec, unsigned char *veclen) -{ - const struct dccp_hdr *dh = dccp_hdr(skb); - unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb); - unsigned char *opt_ptr; - const unsigned char *opt_end = (unsigned char *)dh + - (dh->dccph_doff * 4); - unsigned char opt, len; - unsigned char *value; - - BUG_ON(offset < 0); - options += offset; - opt_ptr = options; - if (opt_ptr >= opt_end) - return -1; - - while (opt_ptr != opt_end) { - opt = *opt_ptr++; - len = 0; - value = NULL; - - /* Check if this isn't a single byte option */ - if (opt > DCCPO_MAX_RESERVED) { - if (opt_ptr == opt_end) - goto out_invalid_option; - - len = *opt_ptr++; - if (len < 3) - goto out_invalid_option; - /* - * Remove the type and len fields, leaving - * just the value size - */ - len -= 2; - value = opt_ptr; - opt_ptr += len; - - if (opt_ptr > opt_end) - goto out_invalid_option; - } - - switch (opt) { - case DCCPO_ACK_VECTOR_0: - case DCCPO_ACK_VECTOR_1: - *vec = value; - *veclen = len; - return offset + (opt_ptr - options); - } - } - - return -1; - -out_invalid_option: - DCCP_BUG("Invalid option - this should not happen (previous parsing)!"); - return -1; -} - /** * ccid2_rtt_estimator - Sample RTT and compute RTO using RFC2988 algorithm * This code is almost identical with TCP's tcp_rtt_estimator(), since @@ -432,16 +370,28 @@ static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp) ccid2_change_l_ack_ratio(sk, hc->tx_cwnd); } +static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type, + u8 option, u8 *optval, u8 optlen) +{ + struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); + + switch (option) { + case DCCPO_ACK_VECTOR_0: + case DCCPO_ACK_VECTOR_1: + return dccp_ackvec_parsed_add(&hc->tx_av_chunks, optval, optlen, + option - DCCPO_ACK_VECTOR_0); + } + return 0; +} + static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) { struct dccp_sock *dp = dccp_sk(sk); struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk); const bool sender_was_blocked = ccid2_cwnd_network_limited(hc); + struct dccp_ackvec_parsed *avp; u64 ackno, seqno; struct ccid2_seq *seqp; - unsigned char *vector; - unsigned char veclen; - int offset = 0; int done = 0; unsigned int maxincr = 0; @@ -475,17 +425,12 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) } /* check forward path congestion */ - /* still didn't send out new data packets */ - if (hc->tx_seqh == hc->tx_seqt) + if (dccp_packet_without_ack(skb)) return; - switch (DCCP_SKB_CB(skb)->dccpd_type) { - case DCCP_PKT_ACK: - case DCCP_PKT_DATAACK: - break; - default: - return; - } + /* still didn't send out new data packets */ + if (hc->tx_seqh == hc->tx_seqt) + goto done; ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; if (after48(ackno, hc->tx_high_ack)) @@ -509,15 +454,16 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2); /* go through all ack vectors */ - while ((offset = ccid2_ackvector(sk, skb, offset, - &vector, &veclen)) != -1) { + list_for_each_entry(avp, &hc->tx_av_chunks, node) { /* go through this ack vector */ - while (veclen--) { - u64 ackno_end_rl = SUB48(ackno, dccp_ackvec_runlen(vector)); + for (; avp->len--; avp->vec++) { + u64 ackno_end_rl = SUB48(ackno, + dccp_ackvec_runlen(avp->vec)); - ccid2_pr_debug("ackvec start:%llu end:%llu\n", + ccid2_pr_debug("ackvec %llu |%u,%u|\n", (unsigned long long)ackno, - (unsigned long long)ackno_end_rl); + dccp_ackvec_state(avp->vec) >> 6, + dccp_ackvec_runlen(avp->vec)); /* if the seqno we are analyzing is larger than the * current ackno, then move towards the tail of our * seqnos. @@ -536,7 +482,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) * run length */ while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) { - const u8 state = dccp_ackvec_state(vector); + const u8 state = dccp_ackvec_state(avp->vec); /* new packet received or marked */ if (state != DCCPAV_NOT_RECEIVED && @@ -563,7 +509,6 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) break; ackno = SUB48(ackno_end_rl, 1); - vector++; } if (done) break; @@ -631,10 +576,11 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) sk_stop_timer(sk, &hc->tx_rtotimer); else sk_reset_timer(sk, &hc->tx_rtotimer, jiffies + hc->tx_rto); - +done: /* check if incoming Acks allow pending packets to be sent */ if (sender_was_blocked && !ccid2_cwnd_network_limited(hc)) tasklet_schedule(&dccp_sk(sk)->dccps_xmitlet); + dccp_ackvec_parsed_cleanup(&hc->tx_av_chunks); } static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) @@ -663,6 +609,7 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk) hc->tx_last_cong = ccid2_time_stamp; setup_timer(&hc->tx_rtotimer, ccid2_hc_tx_rto_expire, (unsigned long)sk); + INIT_LIST_HEAD(&hc->tx_av_chunks); return 0; } @@ -696,16 +643,17 @@ static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb) } struct ccid_operations ccid2_ops = { - .ccid_id = DCCPC_CCID2, - .ccid_name = "TCP-like", - .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock), - .ccid_hc_tx_init = ccid2_hc_tx_init, - .ccid_hc_tx_exit = ccid2_hc_tx_exit, - .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet, - .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent, - .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv, - .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock), - .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv, + .ccid_id = DCCPC_CCID2, + .ccid_name = "TCP-like", + .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock), + .ccid_hc_tx_init = ccid2_hc_tx_init, + .ccid_hc_tx_exit = ccid2_hc_tx_exit, + .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet, + .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent, + .ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options, + .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv, + .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock), + .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv, }; #ifdef CONFIG_IP_DCCP_CCID2_DEBUG diff --git a/net/dccp/ccids/ccid2.h b/net/dccp/ccids/ccid2.h index 25cb6b216ed..e9985dafc2c 100644 --- a/net/dccp/ccids/ccid2.h +++ b/net/dccp/ccids/ccid2.h @@ -55,6 +55,7 @@ struct ccid2_seq { * @tx_rtt_seq: to decay RTTVAR at most once per flight * @tx_rpseq: last consecutive seqno * @tx_rpdupack: dupacks since rpseq + * @tx_av_chunks: list of Ack Vectors received on current skb */ struct ccid2_hc_tx_sock { u32 tx_cwnd; @@ -79,6 +80,7 @@ struct ccid2_hc_tx_sock { int tx_rpdupack; u32 tx_last_cong; u64 tx_high_ack; + struct list_head tx_av_chunks; }; static inline bool ccid2_cwnd_network_limited(struct ccid2_hc_tx_sock *hc) diff --git a/net/dccp/options.c b/net/dccp/options.c index dabd6ee34d4..f06ffcfc8d7 100644 --- a/net/dccp/options.c +++ b/net/dccp/options.c @@ -128,13 +128,6 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq, if (rc) goto out_featneg_failed; break; - case DCCPO_ACK_VECTOR_0: - case DCCPO_ACK_VECTOR_1: - if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */ - break; - dccp_pr_debug("%s Ack Vector (len=%u)\n", dccp_role(sk), - len); - break; case DCCPO_TIMESTAMP: if (len != 4) goto out_invalid_option; @@ -224,6 +217,16 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq, pkt_type, opt, value, len)) goto out_invalid_option; break; + case DCCPO_ACK_VECTOR_0: + case DCCPO_ACK_VECTOR_1: + if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */ + break; + /* + * Ack vectors are processed by the TX CCID if it is + * interested. The RX CCID need not parse Ack Vectors, + * since it is only interested in clearing old state. + * Fall through. + */ case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC: if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk, pkt_type, opt, value, len)) -- cgit v1.2.3 From f72f2f4cdeb67bc262d80a6d474292f00182a4dc Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Thu, 18 Nov 2010 09:37:07 -0800 Subject: dccp ccid-2: whitespace fix-up This fixes whitespace noise introduced in commit "dccp ccid-2: Algorithm to update buffer state", 5753fdfe8bd8e9a2ff9e5af19b0ffc78bfcd502a, 14 Nov 2010. Signed-off-by: Gerrit Renker Signed-off-by: David S. Miller --- net/dccp/ackvec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/dccp/ackvec.c') diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c index 41819848bdd..25b7a8d1ad5 100644 --- a/net/dccp/ackvec.c +++ b/net/dccp/ackvec.c @@ -282,7 +282,7 @@ void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb) * packet of group (2) in 11.4.2. */ void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno) - { +{ struct dccp_ackvec_record *avr, *next; u8 runlen_now, eff_runlen; s64 delta; -- cgit v1.2.3