Return-path: Received: from mail-wm0-f65.google.com ([74.125.82.65]:36917 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751010AbeBITKt (ORCPT ); Fri, 9 Feb 2018 14:10:49 -0500 Received: by mail-wm0-f65.google.com with SMTP id v71so18170977wmv.2 for ; Fri, 09 Feb 2018 11:10:48 -0800 (PST) Subject: Re: [PATCH] mac80211: round IEEE80211_TX_STATUS_HEADROOM up to multiple of 4 To: Felix Fietkau , linux-wireless@vger.kernel.org References: <20180209185100.22511-1-nbd@nbd.name> Cc: johannes@sipsolutions.net From: Arend van Spriel Message-ID: <5A7DF237.9020803@broadcom.com> (sfid-20180209_201053_742425_D77BE3B4) Date: Fri, 9 Feb 2018 20:10:47 +0100 MIME-Version: 1.0 In-Reply-To: <20180209185100.22511-1-nbd@nbd.name> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2/9/2018 7:51 PM, Felix Fietkau wrote: > This ensures that mac80211 allocated management frames are properly > aligned, which makes copying them more efficient. > For instance, mt76 uses iowrite32_copy to copy beacon frames to beacon > template memory on the chip. > Misaligned 32-bit accesses cause CPU exceptions on MIPS and should be > avoided. > > Signed-off-by: Felix Fietkau > --- > include/net/mac80211.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/net/mac80211.h b/include/net/mac80211.h > index 906e90223066..d999b8c8a44b 100644 > --- a/include/net/mac80211.h > +++ b/include/net/mac80211.h > @@ -4149,7 +4149,7 @@ void ieee80211_sta_uapsd_trigger(struct ieee80211_sta *sta, u8 tid); > * The TX headroom reserved by mac80211 for its own tx_status functions. > * This is enough for the radiotap header. Hi Felix, Maybe useful to mention the alignment requirement in this comment block. > */ > -#define IEEE80211_TX_STATUS_HEADROOM 14 > +#define IEEE80211_TX_STATUS_HEADROOM 16 Regards, Arend