2016-10-15 11:28:26

by michael-dev

[permalink] [raw]
Subject: [PATCHv5 1/2] mac80211: avoid extra memcpy in A-MSDU head creation

Signed-off-by: Michael Braun <[email protected]>
---
net/mac80211/tx.c | 23 +++++++++++++----------
1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 5023966..56a883b 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3046,11 +3046,11 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
struct ieee80211_local *local = sdata->local;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct ieee80211_hdr *hdr;
- struct ethhdr amsdu_hdr;
+ struct ethhdr *amsdu_hdr;
int hdr_len = fast_tx->hdr_len - sizeof(rfc1042_header);
int subframe_len = skb->len - hdr_len;
void *data;
- u8 *qc;
+ u8 *qc, *h_80211_src, *h_80211_dst;

if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
return false;
@@ -3058,19 +3058,22 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
if (info->control.flags & IEEE80211_TX_CTRL_AMSDU)
return true;

- if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(amsdu_hdr),
+ if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(*amsdu_hdr),
&subframe_len))
return false;

- amsdu_hdr.h_proto = cpu_to_be16(subframe_len);
- memcpy(amsdu_hdr.h_source, skb->data + fast_tx->sa_offs, ETH_ALEN);
- memcpy(amsdu_hdr.h_dest, skb->data + fast_tx->da_offs, ETH_ALEN);
+ data = skb_push(skb, sizeof(*amsdu_hdr));
+ memmove(data, data + sizeof(*amsdu_hdr), hdr_len);
+ hdr = data;
+ amsdu_hdr = data + hdr_len;
+ /* h_80211_src/dst is addr* field within hdr */
+ h_80211_src = data + fast_tx->sa_offs;
+ h_80211_dst = data + fast_tx->da_offs;

- data = skb_push(skb, sizeof(amsdu_hdr));
- memmove(data, data + sizeof(amsdu_hdr), hdr_len);
- memcpy(data + hdr_len, &amsdu_hdr, sizeof(amsdu_hdr));
+ amsdu_hdr->h_proto = cpu_to_be16(subframe_len);
+ ether_addr_copy(amsdu_hdr->h_source, h_80211_src);
+ ether_addr_copy(amsdu_hdr->h_dest, h_80211_dst);

- hdr = data;
qc = ieee80211_get_qos_ctl(hdr);
*qc |= IEEE80211_QOS_CTL_A_MSDU_PRESENT;

--
2.1.4


2016-10-17 10:39:37

by Johannes Berg

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Subject: Re: [Projekt-wlan] [PATCHv5 2/2] mac80211: fix A-MSDU outer SA/DA

On Mon, 2016-10-17 at 12:29 +0200, michael-dev wrote:

> ether_addr_copy requires both arguments to be __aligned(2) according
> to 
> include/linux/etherdevice.h.
> bssid might be sdata->u.mgd.bssid, which is bssid in struct 
> ieee80211_if_managed, but neither sdata->u, sdata->u.mgd nor 
> sdata->u.mgd.bssid seem to be declared as __aligned(2).So
> ether_addr_copy should not be used.

They are in fact aligned today, given that they occur after a pointer.
However, I did add the __aligned(2) annotation to make that plenty
clear for the future.

johannes

2016-10-17 09:44:26

by Johannes Berg

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Subject: Re: [PATCHv5 2/2] mac80211: fix A-MSDU outer SA/DA

On Sat, 2016-10-15 at 13:28 +0200, Michael Braun wrote:
> According to IEEE 802.11-2012 section 8.3.2 table 8-19, the outer
> SA/DA
> of A-MSDU frames need to be changed depending on FromDS/ToDS values.

Also applied,

> + if (bssid && ieee80211_has_fromds(hdr->frame_control))
> + memcpy(h_80211_src, bssid, ETH_ALEN);
> +
> + if (bssid && ieee80211_has_tods(hdr->frame_control))
> + memcpy(h_80211_dst, bssid, ETH_ALEN);

but I also changed these to ether_addr_copy()

johannes

2016-10-15 11:28:28

by michael-dev

[permalink] [raw]
Subject: [PATCHv5 2/2] mac80211: fix A-MSDU outer SA/DA

According to IEEE 802.11-2012 section 8.3.2 table 8-19, the outer SA/DA
of A-MSDU frames need to be changed depending on FromDS/ToDS values.

Signed-off-by: Michael Braun <[email protected]>

--
v5:
- single out amsdu_hdr to ptr conversion before
v4:
- h_80211_src/dst has been memmove'd and thus needs to be fixed
v3:
- write to outer 802.11 header instead of inner amsdu subframe header
v2:
- avoid the extra write to amsdu_hdr
- avoid copy of asmdu_hdr into skb, use ptr instead
---
net/mac80211/tx.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 56a883b..7fcd4b6 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3051,6 +3051,7 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
int subframe_len = skb->len - hdr_len;
void *data;
u8 *qc, *h_80211_src, *h_80211_dst;
+ const u8 *bssid;

if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
return false;
@@ -3074,6 +3075,28 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
ether_addr_copy(amsdu_hdr->h_source, h_80211_src);
ether_addr_copy(amsdu_hdr->h_dest, h_80211_dst);

+ /* according to IEEE 802.11-2012 8.3.2 table 8-19, the outer SA/DA
+ * fields needs to be changed to BSSID for A-MSDU frames depending
+ * on FromDS/ToDS values.
+ */
+ switch (sdata->vif.type) {
+ case NL80211_IFTYPE_STATION:
+ bssid = sdata->u.mgd.bssid;
+ break;
+ case NL80211_IFTYPE_AP:
+ case NL80211_IFTYPE_AP_VLAN:
+ bssid = sdata->vif.addr;
+ break;
+ default:
+ bssid = NULL;
+ }
+
+ if (bssid && ieee80211_has_fromds(hdr->frame_control))
+ memcpy(h_80211_src, bssid, ETH_ALEN);
+
+ if (bssid && ieee80211_has_tods(hdr->frame_control))
+ memcpy(h_80211_dst, bssid, ETH_ALEN);
+
qc = ieee80211_get_qos_ctl(hdr);
*qc |= IEEE80211_QOS_CTL_A_MSDU_PRESENT;

--
2.1.4

2016-10-17 09:41:13

by Johannes Berg

[permalink] [raw]
Subject: Re: [PATCHv5 1/2] mac80211: avoid extra memcpy in A-MSDU head creation

On Sat, 2016-10-15 at 13:28 +0200, Michael Braun wrote:
> Signed-off-by: Michael Braun <[email protected]>

Applied.

johannes

2016-10-17 10:30:01

by michael-dev

[permalink] [raw]
Subject: Re: [Projekt-wlan] [PATCHv5 2/2] mac80211: fix A-MSDU outer SA/DA

Am 17.10.2016 11:44, schrieb Johannes Berg:
>> + if (bssid && ieee80211_has_fromds(hdr->frame_control))
>> + memcpy(h_80211_src, bssid, ETH_ALEN);
>> +
>> + if (bssid && ieee80211_has_tods(hdr->frame_control))
>> + memcpy(h_80211_dst, bssid, ETH_ALEN);
>
> but I also changed these to ether_addr_copy()

ether_addr_copy requires both arguments to be __aligned(2) according to
include/linux/etherdevice.h.
bssid might be sdata->u.mgd.bssid, which is bssid in struct
ieee80211_if_managed, but neither sdata->u, sdata->u.mgd nor
sdata->u.mgd.bssid seem to be declared as __aligned(2).
So ether_addr_copy should not be used.

What am I missing?

Regards,
M. Braun