[3.8.y.z extended stable] Patch "ath9k_htc: make ->sta_rc_update atomic for most calls" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ath9k_htc: make ->sta_rc_update atomic for most calls

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.19.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From f0a453ac98722323c1bc4f0b98f5216e78d4a751 Mon Sep 17 00:00:00 2001
From: Stanislaw Gruszka <sgruszka at redhat.com>
Date: Tue, 28 Jan 2014 09:14:48 +0100
Subject: ath9k_htc: make ->sta_rc_update atomic for most calls

commit 2fa4cb905605c863bf570027233af7afd8149ae4 upstream.

sta_rc_update() callback must be atomic, hence we can not take mutexes
or do other operations, which can sleep in ath9k_htc_sta_rc_update().

I think we can just return from ath9k_htc_sta_rc_update(), if it is
called without IEEE80211_RC_SUPP_RATES_CHANGED bit. That will help
with scheduling while atomic bug for most cases (except mesh and IBSS
modes).

For mesh and IBSS I do not see other solution like creating additional
workqueue, because sending firmware command require us to sleep, but
this can be done in additional patch.

Patch partially fixes bug:
https://bugzilla.redhat.com/show_bug.cgi?id=990955

Signed-off-by: Stanislaw Gruszka <sgruszka at redhat.com>
Signed-off-by: John W. Linville <linville at tuxdriver.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/net/wireless/ath/ath9k/htc_drv_main.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_main.c b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
index 112116b..07f8817 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_main.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
@@ -1329,21 +1329,22 @@ static void ath9k_htc_sta_rc_update(struct ieee80211_hw *hw,
 	struct ath_common *common = ath9k_hw_common(priv->ah);
 	struct ath9k_htc_target_rate trate;

+	if (!(changed & IEEE80211_RC_SUPP_RATES_CHANGED))
+		return;
+
 	mutex_lock(&priv->mutex);
 	ath9k_htc_ps_wakeup(priv);

-	if (changed & IEEE80211_RC_SUPP_RATES_CHANGED) {
-		memset(&trate, 0, sizeof(struct ath9k_htc_target_rate));
-		ath9k_htc_setup_rate(priv, sta, &trate);
-		if (!ath9k_htc_send_rate_cmd(priv, &trate))
-			ath_dbg(common, CONFIG,
-				"Supported rates for sta: %pM updated, rate caps: 0x%X\n",
-				sta->addr, be32_to_cpu(trate.capflags));
-		else
-			ath_dbg(common, CONFIG,
-				"Unable to update supported rates for sta: %pM\n",
-				sta->addr);
-	}
+	memset(&trate, 0, sizeof(struct ath9k_htc_target_rate));
+	ath9k_htc_setup_rate(priv, sta, &trate);
+	if (!ath9k_htc_send_rate_cmd(priv, &trate))
+		ath_dbg(common, CONFIG,
+			"Supported rates for sta: %pM updated, rate caps: 0x%X\n",
+			sta->addr, be32_to_cpu(trate.capflags));
+	else
+		ath_dbg(common, CONFIG,
+			"Unable to update supported rates for sta: %pM\n",
+			sta->addr);

 	ath9k_htc_ps_restore(priv);
 	mutex_unlock(&priv->mutex);
--
1.8.3.2