Hi Linus, from the time where the messages come (the printk is removed in the submitted version of the patch BTW), we can see that there is a 30 second period between the protection time starts - as it is supposed to be. I guess you have stopped your broadcast ping after ~900 seconds, but still receive packets some time later. Do you have some dumps or any analysis data for this? I will try to rebuild your setup and turn the broadcast replies on later. Thanks for testing. Simon On Tue, Apr 06, 2010 at 11:33:31AM +0200, Linus Lüssing wrote: > Hi Simon, > > sorry, I need to resign my ack again, I guess. I now noticed that > I couldn't reproduce the issue anymore because of not being able > to produce enough broadcasts (~3x83 small packets per second). > It turned out, that the ping utility itself seems to limit the > interval when it gets no icmp reply although flood-ping is > activated. So with setting "/proc/sys/net/ipv4/icmp_echo_ignore_broadcasts" > to 0 on the host which produces the icmp requests, I could produce > ~7000 packets per second again - the ping utilitly seems to use > the icmp replies as a flow control, I guess. > > And then the issue seems to still be there here. I start the > broadcast-flood-ping in a setup A - B - C on node A and stop it > again on node A a second later. Then the icmp-packets still > bounce between B and C until B stops with no more memory available > (haven't applied your 2nd patch for limiting the queue yet). > > From your original patch, I'm getting only one "XXX protected it messages" on A and C, > but a lot more on B: > [ 416.612253] XXX protect it! > [ 446.618569] XXX protect it! > [ 476.824103] XXX protect it! > [ 506.836694] XXX protect it! > [ 537.036869] XXX protect it! > [ 567.056133] XXX protect it! > [ 597.058637] XXX protect it! > [ 847.936099] XXX protect it! > [ 848.560450] XXX protect it! > [ 907.686827] XXX protect it! > [ 1994.836111] XXX protect it! > > Cheers, Linus > > On Mon, Apr 05, 2010 at 12:01:20AM +0200, Simon Wunderlich wrote: > > BATMAN and broadcast packets are tracked with a sequence number window of > > currently 64 entries to measure and avoid duplicates. Packets which have a > > sequence number smaller than the newest received packet minus 64 are not > > within this sequence number window anymore and are called "old packets" from > > now on. > > > > When old packets are received, the routing code assumes that the host of the > > originator has been restarted. This assumption however might be wrong as > > packets can also be delayed by NIC drivers, e.g. because of long queues or > > collision detection in dense WiFi environments. This behaviour can be > > reproduced by doing a broadcast ping flood in a dense node environment. > > > > The effect is that the sequence number window is jumping forth and back, > > accepting and forwarding any packet (because packets are assumed to be "new") > > and causing loops. > > > > To overcome this problem, the sequence number handling has been reorganized. > > When an old packet is received, the window is reset back only once. Other old > > packets are dropped for (currently) 30 seconds to "protect" the new sequence > > number and avoid the hopping as described above. > > > > The reorganization brings some code cleanups (at least i hope you feel the > > same) and also fixes a bug in count_real_packets() which falsely updated > > the last_real_seqno for slightly older packets within the seqno window > > if they are no duplicates. > > > > Signed-off-by: Simon Wunderlich > > Acked-by: Linus Luessing > > > > Index: a/batman-adv-kernelland/types.h > > =================================================================== > > --- a/batman-adv-kernelland/types.h (revision 1616) > > +++ a/batman-adv-kernelland/types.h (working copy) > > @@ -55,6 +55,10 @@ > > uint8_t tq_own; > > int tq_asym_penalty; > > unsigned long last_valid; /* when last packet from this node was received */ > > + unsigned long bcast_seqno_reset; /* time when the broadcast > > + seqno window was reset. */ > > + unsigned long batman_seqno_reset;/* time when the batman seqno > > + window was reset. */ > > uint8_t gw_flags; /* flags related to gateway class */ > > uint8_t flags; /* for now only VIS_SERVER flag. */ > > unsigned char *hna_buff; > > Index: a/batman-adv-kernelland/bitarray.c > > =================================================================== > > --- a/batman-adv-kernelland/bitarray.c (revision 1616) > > +++ a/batman-adv-kernelland/bitarray.c (working copy) > > @@ -111,48 +111,74 @@ > > seq_bits[i] = 0; > > } > > > > +static void bit_reset_window(TYPE_OF_WORD *seq_bits) > > +{ > > + int i; > > + for (i = 0; i < NUM_WORDS; i++) > > + seq_bits[i] = 0; > > +} > > > > -/* receive and process one packet, returns 1 if received seq_num is considered > > - * new, 0 if old */ > > + > > +/* receive and process one packet within the sequence number window. > > + * > > + * returns: > > + * 1 if the window was moved (either new or very old) > > + * 0 if the window was not moved/shifted. > > + */ > > char bit_get_packet(TYPE_OF_WORD *seq_bits, int16_t seq_num_diff, > > int8_t set_mark) > > { > > - int i; > > + /* sequence number is slightly older. We already got a sequence number > > + * higher than this one, so we just mark it. */ > > > > - /* we already got a sequence number higher than this one, so we just > > - * mark it. this should wrap around the integer just fine */ > > if ((seq_num_diff < 0) && (seq_num_diff >= -TQ_LOCAL_WINDOW_SIZE)) { > > if (set_mark) > > bit_mark(seq_bits, -seq_num_diff); > > return 0; > > } > > > > - /* it seems we missed a lot of packets or the other host restarted */ > > - if ((seq_num_diff > TQ_LOCAL_WINDOW_SIZE) || > > - (seq_num_diff < -TQ_LOCAL_WINDOW_SIZE)) { > > + /* sequence number is slightly newer, so we shift the window and > > + * set the mark if required */ > > > > - if (seq_num_diff > TQ_LOCAL_WINDOW_SIZE) > > - bat_dbg(DBG_BATMAN, > > - "We missed a lot of packets (%i) !\n", > > - seq_num_diff-1); > > + if ((seq_num_diff >= 0) && (seq_num_diff <= TQ_LOCAL_WINDOW_SIZE)) { > > + bit_shift(seq_bits, seq_num_diff); > > > > - if (-seq_num_diff > TQ_LOCAL_WINDOW_SIZE) > > - bat_dbg(DBG_BATMAN, > > - "Other host probably restarted !\n"); > > + if (set_mark) > > + bit_mark(seq_bits, 0); > > + return 1; > > + } > > > > - for (i = 0; i < NUM_WORDS; i++) > > - seq_bits[i] = 0; > > + /* sequence number is much newer, probably missed a lot of packets */ > > > > + if (seq_num_diff > TQ_LOCAL_WINDOW_SIZE) { > > + bat_dbg(DBG_BATMAN, > > + "We missed a lot of packets (%i) !\n", > > + seq_num_diff - 1); > > + bit_reset_window(seq_bits); > > if (set_mark) > > - seq_bits[0] = 1; /* we only have the latest packet */ > > - } else { > > - bit_shift(seq_bits, seq_num_diff); > > + bit_mark(seq_bits, 0); > > + return 1; > > + } > > > > + /* received a much older packet. The other host either restarted > > + * or the old packet got delayed somewhere in the network. The > > + * packet should be dropped without calling this function if the > > + * seqno window is protected. */ > > + > > + if (-seq_num_diff > TQ_LOCAL_WINDOW_SIZE) { > > + > > + bat_dbg(DBG_BATMAN, > > + "Other host probably restarted!\n"); > > + > > + bit_reset_window(seq_bits); > > if (set_mark) > > bit_mark(seq_bits, 0); > > + > > + return 1; > > } > > > > - return 1; > > + /* never reached */ > > + return 0; > > } > > > > /* count the hamming weight, how many good packets did we receive? just count > > Index: a/batman-adv-kernelland/originator.c > > =================================================================== > > --- a/batman-adv-kernelland/originator.c (revision 1616) > > +++ a/batman-adv-kernelland/originator.c (working copy) > > @@ -141,6 +141,8 @@ > > orig_node->router = NULL; > > orig_node->batman_if = NULL; > > orig_node->hna_buff = NULL; > > + orig_node->bcast_seqno_reset = jiffies; > > + orig_node->batman_seqno_reset = jiffies; > > > > size = num_ifs * sizeof(TYPE_OF_WORD) * NUM_WORDS; > > > > Index: a/batman-adv-kernelland/routing.c > > =================================================================== > > --- a/batman-adv-kernelland/routing.c (revision 1616) > > +++ a/batman-adv-kernelland/routing.c (working copy) > > @@ -323,6 +323,37 @@ > > gw_check_election(bat_priv, orig_node); > > } > > > > +/* checks whether the host restarted and is in the protection time. > > + * returns: > > + * 0 if the packet is to be accepted > > + * 1 if the packet is to be ignored. > > + */ > > +static int window_protected(int16_t seq_num_diff, > > + unsigned long *last_reset) > > +{ > > + if (-seq_num_diff > TQ_LOCAL_WINDOW_SIZE) { > > + if (time_after(jiffies, *last_reset + > > + msecs_to_jiffies(RESET_PROTECTION_MS))) { > > + > > + *last_reset = jiffies; > > + bat_dbg(DBG_BATMAN, > > + "old packet received, start protection\n"); > > + > > + return 0; > > + } else > > + return 1; > > + } > > + return 0; > > +} > > + > > +/* processes a batman packet for all interfaces, adjusts the sequence number and > > + * finds out whether it is a duplicate. > > + * returns: > > + * 1 the packet is a duplicate > > + * 0 the packet has not yet been received > > + * -1 the packet is old and has been received while the seqno window > > + * was protected. Caller should drop it. > > + */ > > static char count_real_packets(struct ethhdr *ethhdr, > > struct batman_packet *batman_packet, > > struct batman_if *if_incoming) > > @@ -330,31 +361,41 @@ > > struct orig_node *orig_node; > > struct neigh_node *tmp_neigh_node; > > char is_duplicate = 0; > > - uint16_t seq_diff; > > + int16_t seq_diff; > > + int need_update = 0; > > + int set_mark; > > > > orig_node = get_orig_node(batman_packet->orig); > > if (orig_node == NULL) > > return 0; > > > > + seq_diff = batman_packet->seqno - orig_node->last_real_seqno; > > + > > + /* signalize caller that the packet is to be dropped. */ > > + if (window_protected(seq_diff, &orig_node->batman_seqno_reset)) > > + return -1; > > + > > list_for_each_entry(tmp_neigh_node, &orig_node->neigh_list, list) { > > > > - if (!is_duplicate) > > - is_duplicate = > > - get_bit_status(tmp_neigh_node->real_bits, > > + is_duplicate |= get_bit_status(tmp_neigh_node->real_bits, > > orig_node->last_real_seqno, > > batman_packet->seqno); > > - seq_diff = batman_packet->seqno - orig_node->last_real_seqno; > > + > > if (compare_orig(tmp_neigh_node->addr, ethhdr->h_source) && > > (tmp_neigh_node->if_incoming == if_incoming)) > > - bit_get_packet(tmp_neigh_node->real_bits, seq_diff, 1); > > + set_mark = 1; > > else > > - bit_get_packet(tmp_neigh_node->real_bits, seq_diff, 0); > > + set_mark = 0; > > > > + /* if the window moved, set the update flag. */ > > + need_update |= bit_get_packet(tmp_neigh_node->real_bits, > > + seq_diff, set_mark); > > + > > tmp_neigh_node->real_packet_count = > > bit_packet_count(tmp_neigh_node->real_bits); > > } > > > > - if (!is_duplicate) { > > + if (need_update) { > > bat_dbg(DBG_BATMAN, "updating last_seqno: old %d, new %d\n", > > orig_node->last_real_seqno, batman_packet->seqno); > > orig_node->last_real_seqno = batman_packet->seqno; > > @@ -587,24 +628,27 @@ > > return; > > } > > > > - if (batman_packet->tq == 0) { > > - count_real_packets(ethhdr, batman_packet, if_incoming); > > - > > - bat_dbg(DBG_BATMAN, "Drop packet: originator packet with tq equal 0\n"); > > - return; > > - } > > - > > if (is_my_oldorig) { > > bat_dbg(DBG_BATMAN, "Drop packet: ignoring all rebroadcast echos (sender: %pM)\n", ethhdr->h_source); > > return; > > } > > > > - is_duplicate = count_real_packets(ethhdr, batman_packet, if_incoming); > > - > > orig_node = get_orig_node(batman_packet->orig); > > if (orig_node == NULL) > > return; > > > > + is_duplicate = count_real_packets(ethhdr, batman_packet, if_incoming); > > + > > + if (is_duplicate == -1) { > > + bat_dbg(DBG_BATMAN, "Drop packet: packet within seqno protection time (sender: %pM)\n", ethhdr->h_source); > > + return; > > + } > > + > > + if (batman_packet->tq == 0) { > > + bat_dbg(DBG_BATMAN, "Drop packet: originator packet with tq equal 0\n"); > > + return; > > + } > > + > > /* avoid temporary routing loops */ > > if ((orig_node->router) && > > (orig_node->router->orig_node->router) && > > @@ -1088,6 +1132,7 @@ > > struct bcast_packet *bcast_packet; > > struct ethhdr *ethhdr; > > int hdr_size = sizeof(struct bcast_packet); > > + int16_t seq_diff; > > unsigned long flags; > > > > /* drop packet if it has not necessary minimum size */ > > @@ -1123,7 +1168,7 @@ > > return NET_RX_DROP; > > } > > > > - /* check flood history */ > > + /* check whether the packet is a duplicate */ > > if (get_bit_status(orig_node->bcast_bits, > > orig_node->last_bcast_seqno, > > ntohs(bcast_packet->seqno))) { > > @@ -1131,14 +1176,20 @@ > > return NET_RX_DROP; > > } > > > > - /* mark broadcast in flood history */ > > - if (bit_get_packet(orig_node->bcast_bits, > > - ntohs(bcast_packet->seqno) - > > - orig_node->last_bcast_seqno, 1)) > > + seq_diff = ntohs(bcast_packet->seqno) - orig_node->last_bcast_seqno; > > + > > + /* check whether the packet is old and the host just restarted. */ > > + if (window_protected(seq_diff, &orig_node->bcast_seqno_reset)) { > > + spin_unlock_irqrestore(&orig_hash_lock, flags); > > + return NET_RX_DROP; > > + } > > + > > + /* mark broadcast in flood history, update window position > > + * if required. */ > > + if (bit_get_packet(orig_node->bcast_bits, seq_diff, 1)) > > orig_node->last_bcast_seqno = ntohs(bcast_packet->seqno); > > > > spin_unlock_irqrestore(&orig_hash_lock, flags); > > - > > /* rebroadcast packet */ > > add_bcast_packet_to_list(skb); > > > > Index: a/batman-adv-kernelland/main.h > > =================================================================== > > --- a/batman-adv-kernelland/main.h (revision 1616) > > +++ a/batman-adv-kernelland/main.h (working copy) > > @@ -66,6 +66,9 @@ > > * forw_packet->direct_link_flags */ > > #define MAX_AGGREGATION_MS 100 > > > > +#define RESET_PROTECTION_MS 30000 > > +/* don't reset again within 30 seconds */ > > + > > #define MODULE_INACTIVE 0 > > #define MODULE_ACTIVE 1 > > #define MODULE_DEACTIVATING 2 > > >