linux-kernel - [ 78/82] iwlwifi: disable greenfield transmissions as a workaround

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20120813201753.279520441@linuxfoundation.org>
Date:	Mon, 13 Aug 2012 13:19:54 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
	Cesar Eduardo Barros <cesarb@...arb.net>,
	Johannes Berg <johannes.berg@...el.com>,
	"John W. Linville" <linville@...driver.com>
Subject: [ 78/82] iwlwifi: disable greenfield transmissions as a workaround

From: Greg KH <gregkh@...uxfoundation.org>

3.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johannes Berg <johannes.berg@...el.com>

commit 50e2a30cf6fcaeb2d27360ba614dd169a10041c5 upstream.

There's a bug that causes the rate scaling to get stuck
when it has to use single-stream rates with a peer that
can do GF and SGI; the two are incompatible so we can't
use them together, but that causes the algorithm to not
work at all, it always rejects updates.

Disable greenfield for now to prevent that problem.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@...el.com>
Tested-by: Cesar Eduardo Barros <cesarb@...arb.net>
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: John W. Linville <linville@...driver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/iwlwifi/iwl-agn-rs.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rs.c
@@ -709,11 +709,14 @@ static int rs_toggle_antenna(u32 valid_a
  */
 static bool rs_use_green(struct ieee80211_sta *sta)
 {
-	struct iwl_station_priv *sta_priv = (void *)sta->drv_priv;
-	struct iwl_rxon_context *ctx = sta_priv->ctx;
-
-	return (sta->ht_cap.cap & IEEE80211_HT_CAP_GRN_FLD) &&
-		!(ctx->ht.non_gf_sta_present);
+	/*
+	 * There's a bug somewhere in this code that causes the
+	 * scaling to get stuck because GF+SGI can't be combined
+	 * in SISO rates. Until we find that bug, disable GF, it
+	 * has only limited benefit and we still interoperate with
+	 * GF APs since we can always receive GF transmissions.
+	 */
+	return false;
 }
 
 /**


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/