iwlegacy: fix channel switch locking

We use priv->mutex to avoid race conditions between chswitch_done()
and mac_channel_switch(), when marking channel switch in
progress. But chswitch_done() can be called in atomic context
from rx_csa() or with mutex already taken from commit_rxon().

To fix remove mutex from chswitch_done() and use atomic bitops
for marking channel switch pending.

Cc: stable@kernel.org # 2.6.39+
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 10 insertions, 10 deletions

diff --git a/drivers/net/wireless/iwlegacy/iwl4965-base.c b/drivers/net/wireless/iwlegacy/iwl4965-base.c
index af2ae22fcfd3..7157ba529680 100644
--- a/drivers/net/wireless/iwlegacy/iwl4965-base.c
+++ b/drivers/net/wireless/iwlegacy/iwl4965-base.c
@@ -2861,16 +2861,13 @@ void iwl4965_mac_channel_switch(struct ieee80211_hw *hw,
                 goto out;
 
         if (test_bit(STATUS_EXIT_PENDING, &priv->status) ||
-            test_bit(STATUS_SCANNING, &priv->status))
+            test_bit(STATUS_SCANNING, &priv->status) ||
+            test_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status))
                 goto out;
 
         if (!iwl_legacy_is_associated_ctx(ctx))
                 goto out;
 
-        /* channel switch in progress */
-        if (priv->switch_rxon.switch_in_progress == true)
-                goto out;
-
         if (priv->cfg->ops->lib->set_channel_switch) {
 
                 ch = channel->hw_value;
@@ -2919,15 +2916,18 @@ void iwl4965_mac_channel_switch(struct ieee80211_hw *hw,
                          * at this point, staging_rxon has the
                          * configuration for channel switch
                          */
-                        if (priv->cfg->ops->lib->set_channel_switch(priv,
-                                                                    ch_switch))
-                                priv->switch_rxon.switch_in_progress = false;
+                        set_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status);
+                        priv->switch_channel = cpu_to_le16(ch);
+                        if (priv->cfg->ops->lib->set_channel_switch(priv, ch_switch)) {
+                                clear_bit(STATUS_CHANNEL_SWITCH_PENDING,
+                                          &priv->status);
+                                priv->switch_channel = 0;
+                                ieee80211_chswitch_done(ctx->vif, false);
+                        }
                 }
         }
 out:
         mutex_unlock(&priv->mutex);
-        if (!priv->switch_rxon.switch_in_progress)
-                ieee80211_chswitch_done(ctx->vif, false);
         IWL_DEBUG_MAC80211(priv, "leave\n");
 }