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authorJohannes Berg <johannes.berg@intel.com>2011-04-01 13:52:34 +0200
committerJohn W. Linville <linville@tuxdriver.com>2011-04-04 15:22:11 -0400
commit5312c3f60ba49073081b2dc421f9f3c22dd43d99 (patch)
treece0a8a64ba88eb044b2c46721086b597fcf46cce /include/net
parent8f06ca2c83689f4d352a34ef1c484f40c25b41ed (diff)
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 <egrumbach@gmail.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/mac80211.h15
1 files changed, 13 insertions, 2 deletions
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.
*