| Message ID | 1379943278-1014-1-git-send-email-michal.kazior@tieto.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Mon, 2013-09-23 at 15:34 +0200, Michal Kazior wrote: > Some devices may not be able to report A-MSDUs in > single buffers. Drivers for such devices were > forced to re-assemble A-MSDUs which would then > be eventually disassembled by mac80211. This could > lead to CPU cache thrashing and poor performance. > > Since A-MSDU has a single sequence number all > subframes share it. This was in conflict with > retransmission/duplication recovery > (IEEE802.11-2012: 9.3.2.10). > > Patch introduces a new flag that is meant to be > set for all individually reported A-MSDU subframes > except the last one. This ensures the > last_seq_ctrl is updated after the last subframe > is processed. If an A-MSDU is actually a duplicate > transmission all reported subframes will be > properly discarded. Applied. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/net/mac80211.h b/include/net/mac80211.h index 06ffae8..f8f049d 100644 --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -829,6 +829,15 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info) * @RX_FLAG_STBC_MASK: STBC 2 bit bitmask. 1 - Nss=1, 2 - Nss=2, 3 - Nss=3 * @RX_FLAG_10MHZ: 10 MHz (half channel) was used * @RX_FLAG_5MHZ: 5 MHz (quarter channel) was used + * @RX_FLAG_AMSDU_MORE: Some drivers may prefer to report separate A-MSDU + * subframes instead of a one huge frame for performance reasons. + * All, but the last MSDU from an A-MSDU should have this flag set. E.g. + * if an A-MSDU has 3 frames, the first 2 must have the flag set, while + * the 3rd (last) one must not have this flag set. The flag is used to + * deal with retransmission/duplication recovery properly since A-MSDU + * subframes share the same sequence number. Reported subframes can be + * either regular MSDU or singly A-MSDUs. Subframes must not be + * interleaved with other frames. */ enum mac80211_rx_flags { RX_FLAG_MMIC_ERROR = BIT(0), @@ -859,6 +868,7 @@ enum mac80211_rx_flags { RX_FLAG_STBC_MASK = BIT(26) | BIT(27), RX_FLAG_10MHZ = BIT(28), RX_FLAG_5MHZ = BIT(29), + RX_FLAG_AMSDU_MORE = BIT(30), }; #define RX_FLAG_STBC_SHIFT 26 diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index 8e908e1..43bee02 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -995,7 +995,7 @@ ieee80211_rx_h_check(struct ieee80211_rx_data *rx) rx->sta->num_duplicates++; } return RX_DROP_UNUSABLE; - } else + } else if (!(status->flag & RX_FLAG_AMSDU_MORE)) rx->sta->last_seq_ctrl[rx->seqno_idx] = hdr->seq_ctrl; }
Some devices may not be able to report A-MSDUs in single buffers. Drivers for such devices were forced to re-assemble A-MSDUs which would then be eventually disassembled by mac80211. This could lead to CPU cache thrashing and poor performance. Since A-MSDU has a single sequence number all subframes share it. This was in conflict with retransmission/duplication recovery (IEEE802.11-2012: 9.3.2.10). Patch introduces a new flag that is meant to be set for all individually reported A-MSDU subframes except the last one. This ensures the last_seq_ctrl is updated after the last subframe is processed. If an A-MSDU is actually a duplicate transmission all reported subframes will be properly discarded. Signed-off-by: Michal Kazior <michal.kazior@tieto.com> --- There were no comments on the RFC so far so I'm posting this as a patch. The first driver that will use this is ath10k. include/net/mac80211.h | 10 ++++++++++ net/mac80211/rx.c | 2 +- 2 files changed, 11 insertions(+), 1 deletion(-)