From: Johannes Berg Date: Fri, 1 Apr 2011 11:52:34 +0000 (+0200) Subject: mac80211: fix comment regarding aggregation buf_size X-Git-Tag: firefly_0821_release~7613^2~1428^2~12^2~32 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5312c3f60ba49073081b2dc421f9f3c22dd43d99;p=firefly-linux-kernel-4.4.55.git mac80211: fix comment regarding aggregation buf_size The description for buf_size was misleading and just said you couldn't TX larger aggregates, but of course you can't TX aggregates in a way that would exceed the window either, which is possible even if the aggregates are shorter than that. Expand the description, thanks to Emmanuel for explaining this to me. Cc: Emmanuel Grumbach Signed-off-by: Johannes Berg Signed-off-by: John W. Linville --- diff --git a/include/net/mac80211.h b/include/net/mac80211.h index cefe1b37c493..965f1b16e53a 100644 --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -1753,8 +1753,19 @@ enum ieee80211_ampdu_mlme_action { * that TX/RX_STOP can pass NULL for this parameter. * The @buf_size parameter is only valid when the action is set to * %IEEE80211_AMPDU_TX_OPERATIONAL and indicates the peer's reorder - * buffer size (number of subframes) for this session -- aggregates - * containing more subframes than this may not be transmitted to the peer. + * buffer size (number of subframes) for this session -- the driver + * may neither send aggregates containing more subframes than this + * nor send aggregates in a way that lost frames would exceed the + * buffer size. If just limiting the aggregate size, this would be + * possible with a buf_size of 8: + * - TX: 1.....7 + * - RX: 2....7 (lost frame #1) + * - TX: 8..1... + * which is invalid since #1 was now re-transmitted well past the + * buffer size of 8. Correct ways to retransmit #1 would be: + * - TX: 1 or 18 or 81 + * Even "189" would be wrong since 1 could be lost again. + * * Returns a negative error code on failure. * The callback can sleep. *