bsd/netinet/tcp_sack.c

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316  * Process cumulative ACK and the TCP SACK option to update the scoreboard.
317  * tp->snd_holes is an ordered list of holes (oldest to newest, in terms of
321 tcp_sack_doack(struct tcpcb *tp, struct tcpopt *to, tcp_seq th_ack)
337 	 * Append received valid SACK blocks to sack_blocks[].
340 		for (i = 0; i < to->to_nsacks; i++) {
341 			bcopy((to->to_sacks + i * TCPOLEN_SACK),
377 		 * Empty scoreboard. Need to initialize snd_fack (it may be
380 		 * the logic that adds holes to the tail of the scoreboard).
386 	 * just one pass in order to reduce the number of compares especially
406 			/* Go to the previous sack block. */
410 			 * We failed to add a new hole based on the current
412 			 * fall completely to the right of snd_fack and proceed
413 			 * to trim the scoreboard based on the remaining sack
437 			 * Go to the previous sack block.
445 			 * Go to the previous hole.
476 				 * ACKs some data in middle of a hole; need to
508  * Free all SACK holes to clear the scoreboard.
526  * is received, force snd_cwnd to a value that will allow
527  * the sender to transmit no more than 2 segments.
529  * later point, but for now, the goal is to prevent the
556  * now to sanity check the hint.
578  * Returns the next hole to retransmit and the number of retransmitted bytes
584  * For the loop to traverse more than 1 link before finding the next hole to
585  * retransmit, we would need to have at least 1 node following the current hint
588  * in order to traverse more 1 link in the loop below, we need to have at least
627  * should be used to avoid retransmitting SACKed data.  This function
628  * traverses the SACK list to see if snd_nxt should be moved forward.
640 	 * Two cases for which we want to advance snd_nxt: