From: Nandita Dukkipati Date: Tue, 21 May 2013 15:12:07 +0000 (+0000) Subject: tcp: bug fix in proportional rate reduction. X-Git-Tag: v3.10-rc3~18^2~5 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=35f079ebbc860dcd1cca70890c9c8d59c1145525;p=pandora-kernel.git tcp: bug fix in proportional rate reduction. This patch is a fix for a bug triggering newly_acked_sacked < 0 in tcp_ack(.). The bug is triggered by sacked_out decreasing relative to prior_sacked, but packets_out remaining the same as pior_packets. This is because the snapshot of prior_packets is taken after tcp_sacktag_write_queue() while prior_sacked is captured before tcp_sacktag_write_queue(). The problem is: tcp_sacktag_write_queue (tcp_match_skb_to_sack() -> tcp_fragment) adjusts the pcount for packets_out and sacked_out (MSS change or other reason). As a result, this delta in pcount is reflected in (prior_sacked - sacked_out) but not in (prior_packets - packets_out). This patch does the following: 1) initializes prior_packets at the start of tcp_ack() so as to capture the delta in packets_out created by tcp_fragment. 2) introduces a new "previous_packets_out" variable that snapshots packets_out right before tcp_clean_rtx_queue, so pkts_acked can be correctly computed as before. 3) Computes pkts_acked using previous_packets_out, and computes newly_acked_sacked using prior_packets. Signed-off-by: Nandita Dukkipati Acked-by: Yuchung Cheng Signed-off-by: David S. Miller --- Reading git-diff-tree failed