On Fri, Jan 25, 2008 at 02:50:37PM -0500, John W. Linville wrote: > On Fri, Jan 25, 2008 at 02:48:07PM -0500, John W. Linville wrote: > > > http://kerneltrap.org/mailarchive/linux-netdev/2007/11/24/442496 > > > > Quoth Herbert Xu: > > > > "OK. Let me clarify this a bit more. We require at least one > > of the following rules to be met: > > > > * the IPv4/IPv6 header is aligned by 8 bytes on reception; > > * or the platform provides unaligned exception handlers. > > > (Hmmm..."aligned by 8 bytes", so our warning and my iwlwifi patch > > may still not be right...) > > http://kerneltrap.org/mailarchive/linux-netdev/2007/11/25/443558 > > More from Herbert: > > "Sorry I was wrong about the 8 bytes requirement. Although the > IPv6 protocol does try to maintain an 8-byte alignment the Linux > stack never does anything that requires that. > > So 4 bytes is enough." > > Phew! Alright, here is my whack at it... The iwl_handle_data_packet_monitor bits are untested, as I appear to be too daft to figure-out how to exercise those paths. Anyway, this is mostly just so we can scope the driver change required in absence of a firmware change. Persumably the changes required if we were to put such code in mac80211 would be similar. John ----- From: John W. Linville <linville@xxxxxxxxxxxxx> Subject: [PATCH] iwlwifi: move data at CPU to ensure 4-byte alignment for payload Ugly, but if the firmware won't cooperate... Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx> --- drivers/net/wireless/iwlwifi/iwl-3945.c | 13 ++++++++++--- drivers/net/wireless/iwlwifi/iwl-4965.c | 10 +++++++++- drivers/net/wireless/iwlwifi/iwl3945-base.c | 10 +++++++++- drivers/net/wireless/iwlwifi/iwl4965-base.c | 10 +++++++++- 4 files changed, 37 insertions(+), 6 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-3945.c b/drivers/net/wireless/iwlwifi/iwl-3945.c index 3a45fe9..06cd28e 100644 --- a/drivers/net/wireless/iwlwifi/iwl-3945.c +++ b/drivers/net/wireless/iwlwifi/iwl-3945.c @@ -252,6 +252,7 @@ static void iwl3945_handle_data_packet(struct iwl_priv *priv, int is_data, struct iwl_rx_frame_hdr *rx_hdr = IWL_RX_HDR(pkt); struct iwl_rx_frame_end *rx_end = IWL_RX_END(pkt); short len = le16_to_cpu(rx_hdr->len); + int hdrlen, align; /* We received data from the HW, so stop the watchdog */ if (unlikely((len + IWL_RX_FRAME_SIZE) > skb_tailroom(rxb->skb))) { @@ -275,11 +276,17 @@ static void iwl3945_handle_data_packet(struct iwl_priv *priv, int is_data, return; } - skb_reserve(rxb->skb, (void *)rx_hdr->payload - (void *)pkt); + hdr = (void *)rx_hdr->payload; + hdrlen = ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_control)); + align = hdrlen & 3; + + skb_reserve(rxb->skb, (void *)rx_hdr->payload - (void *)pkt - align); /* Set the size of the skb to the size of the frame */ - skb_put(rxb->skb, le16_to_cpu(rx_hdr->len)); + skb_put(rxb->skb, len); - hdr = (void *)rxb->skb->data; + /* align payload on 4-byte boundary if necessary */ + if (align) + memmove((void *)hdr - align, hdr, len); if (iwl_param_hwcrypto) iwl_set_decrypted_flag(priv, rxb->skb, diff --git a/drivers/net/wireless/iwlwifi/iwl-4965.c b/drivers/net/wireless/iwlwifi/iwl-4965.c index 891f90d..11eb75b 100644 --- a/drivers/net/wireless/iwlwifi/iwl-4965.c +++ b/drivers/net/wireless/iwlwifi/iwl-4965.c @@ -3496,6 +3496,7 @@ static void iwl4965_handle_data_packet(struct iwl_priv *priv, int is_data, __le32 *rx_end; unsigned int skblen; u32 ampdu_status; + int hdrlen, align; if (!include_phy && priv->last_phy_res[0]) rx_start = (struct iwl4965_rx_phy_res *)&priv->last_phy_res[1]; @@ -3533,10 +3534,17 @@ static void iwl4965_handle_data_packet(struct iwl_priv *priv, int is_data, ampdu_status = le32_to_cpu(*rx_end); skblen = ((u8 *) rx_end - (u8 *) & pkt->u.raw[0]) + sizeof(u32); + hdrlen = ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_control)); + align = hdrlen & 3; + /* start from MAC */ - skb_reserve(rxb->skb, (void *)hdr - (void *)pkt); + skb_reserve(rxb->skb, (void *)hdr - (void *)pkt - align); skb_put(rxb->skb, len); /* end where data ends */ + /* align payload on 4-byte boundary if necessary */ + if (align) + memmove(rxb->skb->data, hdr, len); + /* We only process data packets if the interface is open */ if (unlikely(!priv->is_open)) { IWL_DEBUG_DROP_LIMIT diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c index 1a6b0e0..d6018bd 100644 --- a/drivers/net/wireless/iwlwifi/iwl3945-base.c +++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c @@ -3056,7 +3056,9 @@ void iwl_handle_data_packet_monitor(struct iwl_priv *priv, struct ieee80211_rx_status *stats, u16 phy_flags) { + struct ieee80211_hdr *hdr; struct iwl_rt_rx_hdr *iwl_rt; + int hdrlen, align; /* First cache any information we need before we overwrite * the information provided in the skb from the hardware */ @@ -3072,8 +3074,14 @@ void iwl_handle_data_packet_monitor(struct iwl_priv *priv, return; } + /* determine payload alignment adjustment */ + hdr = data; + hdrlen = ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_control)) + + sizeof(*iwl_rt); + align = 4 - (hdrlen & 3); /* invert align since already at skb head */ + /* copy the frame data to write after where the radiotap header goes */ - iwl_rt = (void *)rxb->skb->data; + iwl_rt = (void *)rxb->skb->data + align; memmove(iwl_rt->payload, data, len); iwl_rt->rt_hdr.it_version = PKTHDR_RADIOTAP_VERSION; diff --git a/drivers/net/wireless/iwlwifi/iwl4965-base.c b/drivers/net/wireless/iwlwifi/iwl4965-base.c index 6cd57c2..9ef9d14 100644 --- a/drivers/net/wireless/iwlwifi/iwl4965-base.c +++ b/drivers/net/wireless/iwlwifi/iwl4965-base.c @@ -3144,7 +3144,9 @@ void iwl_handle_data_packet_monitor(struct iwl_priv *priv, struct ieee80211_rx_status *stats, u16 phy_flags) { + struct ieee80211_hdr *hdr; struct iwl_rt_rx_hdr *iwl_rt; + int hdrlen, align; /* First cache any information we need before we overwrite * the information provided in the skb from the hardware */ @@ -3160,8 +3162,14 @@ void iwl_handle_data_packet_monitor(struct iwl_priv *priv, return; } + /* determine payload alignment adjustment */ + hdr = data; + hdrlen = ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_control)) + + sizeof(*iwl_rt); + align = 4 - (hdrlen & 3); /* invert align since already at skb head */ + /* copy the frame data to write after where the radiotap header goes */ - iwl_rt = (void *)rxb->skb->data; + iwl_rt = (void *)rxb->skb->data + align; memmove(iwl_rt->payload, data, len); iwl_rt->rt_hdr.it_version = PKTHDR_RADIOTAP_VERSION; -- 1.5.3.3 -- John W. Linville linville@xxxxxxxxxxxxx - To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
