From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from xc.sipsolutions.net ([83.246.72.84]:58738 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932682AbZJ1I71 (ORCPT ); Wed, 28 Oct 2009 04:59:27 -0400 Subject: [PATCH] mac80211: fix radiotap header generation From: Johannes Berg To: John Linville Cc: linux-wireless , Bruno Randolf Content-Type: text/plain; charset="UTF-8" Date: Wed, 28 Oct 2009 09:58:52 +0100 Message-ID: <1256720333.4237.106.camel@johannes.local> Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: In commit 601ae7f25aea58f208a7f640f6174aac0652403a Author: Bruno Randolf Date: Thu May 8 19:22:43 2008 +0200 mac80211: make rx radiotap header more flexible code was added that tried to align the radiotap header position in memory based on the radiotap header length. Quite obviously, that is completely useless. Instead of trying to do that, use unaligned accesses to generate the radiotap header. To properly do that, we also need to mark struct ieee80211_radiotap_header packed, but that is fine since it's already packed (and it should be marked packed anyway since its a wire format). Cc: Bruno Randolf Signed-off-by: Johannes Berg --- I'm not sure it should be sent to stable, it only affects platforms that don't do unaligned accesses well. include/net/ieee80211_radiotap.h | 2 +- net/mac80211/rx.c | 26 ++++++++++++-------------- 2 files changed, 13 insertions(+), 15 deletions(-) --- wireless-testing.orig/net/mac80211/rx.c 2009-10-28 08:43:27.000000000 +0100 +++ wireless-testing/net/mac80211/rx.c 2009-10-28 08:58:24.000000000 +0100 @@ -95,10 +95,6 @@ ieee80211_rx_radiotap_len(struct ieee802 if (len & 1) /* padding for RX_FLAGS if necessary */ len++; - /* make sure radiotap starts at a naturally aligned address */ - if (len % 8) - len = roundup(len, 8); - return len; } @@ -116,6 +112,7 @@ ieee80211_add_rx_radiotap_header(struct struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb); struct ieee80211_radiotap_header *rthdr; unsigned char *pos; + u16 rx_flags = 0; rthdr = (struct ieee80211_radiotap_header *)skb_push(skb, rtap_len); memset(rthdr, 0, rtap_len); @@ -134,7 +131,7 @@ ieee80211_add_rx_radiotap_header(struct /* IEEE80211_RADIOTAP_TSFT */ if (status->flag & RX_FLAG_TSFT) { - *(__le64 *)pos = cpu_to_le64(status->mactime); + put_unaligned_le64(status->mactime, pos); rthdr->it_present |= cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT); pos += 8; @@ -166,17 +163,17 @@ ieee80211_add_rx_radiotap_header(struct pos++; /* IEEE80211_RADIOTAP_CHANNEL */ - *(__le16 *)pos = cpu_to_le16(status->freq); + put_unaligned_le16(status->freq, pos); pos += 2; if (status->band == IEEE80211_BAND_5GHZ) - *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_OFDM | - IEEE80211_CHAN_5GHZ); + put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_5GHZ, + pos); else if (rate->flags & IEEE80211_RATE_ERP_G) - *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_OFDM | - IEEE80211_CHAN_2GHZ); + put_unaligned_le16(IEEE80211_CHAN_OFDM | IEEE80211_CHAN_2GHZ, + pos); else - *(__le16 *)pos = cpu_to_le16(IEEE80211_CHAN_CCK | - IEEE80211_CHAN_2GHZ); + put_unaligned_le16(IEEE80211_CHAN_CCK | IEEE80211_CHAN_2GHZ, + pos); pos += 2; /* IEEE80211_RADIOTAP_DBM_ANTSIGNAL */ @@ -205,10 +202,11 @@ ieee80211_add_rx_radiotap_header(struct /* IEEE80211_RADIOTAP_RX_FLAGS */ /* ensure 2 byte alignment for the 2 byte field as required */ - if ((pos - (unsigned char *)rthdr) & 1) + if ((pos - (u8 *)rthdr) & 1) pos++; if (status->flag & RX_FLAG_FAILED_PLCP_CRC) - *(__le16 *)pos |= cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADPLCP); + rx_flags |= IEEE80211_RADIOTAP_F_RX_BADPLCP; + put_unaligned_le16(rx_flags, pos); pos += 2; } --- wireless-testing.orig/include/net/ieee80211_radiotap.h 2009-10-28 08:46:35.000000000 +0100 +++ wireless-testing/include/net/ieee80211_radiotap.h 2009-10-28 08:51:49.000000000 +0100 @@ -80,7 +80,7 @@ struct ieee80211_radiotap_header { * Additional extensions are made * by setting bit 31. */ -}; +} __packed; /* Name Data type Units * ---- --------- -----