ath9k_htc: make ->sta_rc_update atomic for most calls

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

Cc: stable@vger.kernel.org
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files 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 608d739d1378..a57af9b96a39 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_main.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_main.c
@@ -1315,21 +1315,22 @@ 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);