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Date:   Wed, 29 Sep 2021 11:20:01 +0800
From:   Wen Gong <wgong@codeaurora.org>
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     ath11k@lists.infradead.org, linux-wireless@vger.kernel.org
Subject: Re: [PATCH v3 2/2] mac80211: do intersection with he mcs and nss set
 of peer and own
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On 2021-09-28 21:02, Johannes Berg wrote:
> Hi,
> 
> 
> I had done a bunch of fixups to this patch, but the zero-day build 
> robot
> correctly reports that:
> 
>> +	ieee80211_he_mcs_intersection(&own_he_cap.he_mcs_nss_supp.rx_mcs_80,
>> +				      &he_cap->he_mcs_nss_supp.rx_mcs_80,
>> +				      &own_he_cap.he_mcs_nss_supp.tx_mcs_80,
>> +				      &he_cap->he_mcs_nss_supp.tx_mcs_80);
> 
> the &own_he_cap... parts here will take an __le16 pointer to a possibly
> unaligned variable - any thoughts how we could fix that?
> 
Hi Johannes,

Add "__packed" before the "__le16 *" should solve this warning by my 
understand like this:

diff --git a/net/mac80211/he.c b/net/mac80211/he.c
index c05af7018f79..960fea9646b0 100644
--- a/net/mac80211/he.c
+++ b/net/mac80211/he.c
@@ -52,7 +52,7 @@ ieee80211_update_from_he_6ghz_capa(const struct 
ieee80211_he_6ghz_capa *he_6ghz_
         sta->sta.he_6ghz_capa = *he_6ghz_capa;
  }

-static void ieee80211_he_mcs_disable(__le16 *he_mcs)
+static void ieee80211_he_mcs_disable(__packed __le16 *he_mcs)
  {
         u32 i;

@@ -60,8 +60,8 @@ static void ieee80211_he_mcs_disable(__le16 *he_mcs)
                 *he_mcs |= cpu_to_le16(IEEE80211_HE_MCS_NOT_SUPPORTED << 
i * 2);
  }

-static void ieee80211_he_mcs_intersection(__le16 *he_own_rx, __le16 
*he_peer_rx,
-                                         __le16 *he_own_tx, __le16 
*he_peer_tx)
+static void ieee80211_he_mcs_intersection(__packed __le16 *he_own_rx, 
__packed __le16 *he_peer_rx,
+                                         __packed __le16 *he_own_tx, 
__packed __le16 *he_peer_tx)
  {
         u32 i;
         u16 own_rx, own_tx, peer_rx, peer_tx;


net/mac80211/he.c:158:33: warning: taking address of packed member 
'rx_mcs_80' of class or structure 'ieee80211_he_mcs_nss_supp' may result 
in an unaligned pointer value [-Waddress-of-packed-member]

> johannes