2012-03-01 10:24:03

by Felix Fietkau

Subject: [PATCH] mac80211: use 16 bit alignment for the if_ibss bssid field

Several MAC address comparison functions assume 16 bit alignment for pointers
passed to them. Since the addition of the control_port field, alignment
for the IBSS bssid was off by one, causing a severe performance hit on
architectures without efficient unaligned access (e.g. MIPS).

Signed-off-by: Felix Fietkau <[email protected]>
---
net/mac80211/ieee80211_i.h | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index cee0c74..c413058 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -480,7 +480,7 @@ struct ieee80211_if_ibss {

bool control_port;

- u8 bssid[ETH_ALEN];
+ u8 bssid[ETH_ALEN] __aligned(2);
u8 ssid[IEEE80211_MAX_SSID_LEN];
u8 ssid_len, ie_len;
u8 *ie;
--
1.7.3.2

2012-03-01 10:24:30

by Johannes Berg

Subject: Re: [PATCH] mac80211: use 16 bit alignment for the if_ibss bssid field

On Thu, 2012-03-01 at 11:23 +0100, Felix Fietkau wrote:
> Several MAC address comparison functions assume 16 bit alignment for pointers
> passed to them. Since the addition of the control_port field, alignment
> for the IBSS bssid was off by one, causing a severe performance hit on
> architectures without efficient unaligned access (e.g. MIPS).
>
> Signed-off-by: Felix Fietkau <[email protected]>

Acked-by: Johannes Berg <[email protected]>

> ---
> net/mac80211/ieee80211_i.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index cee0c74..c413058 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -480,7 +480,7 @@ struct ieee80211_if_ibss {
>
> bool control_port;
>
> - u8 bssid[ETH_ALEN];
> + u8 bssid[ETH_ALEN] __aligned(2);
> u8 ssid[IEEE80211_MAX_SSID_LEN];
> u8 ssid_len, ie_len;
> u8 *ie;