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>

diff --git a/drivers/net/wireless/iwlegacy/iwl-4965.c b/drivers/net/wireless/iwlegacy/iwl-4965.c
index e1b8922..facc94e 100644 (file)
--- a/drivers/net/wireless/iwlegacy/iwl-4965.c
+++ b/drivers/net/wireless/iwlegacy/iwl-4965.c
@@ -1218,10 +1218,10 @@ static int iwl4965_commit_rxon(struct iwl_priv *priv, struct iwl_rxon_context *c
         * receive commit_rxon request
         * abort any previous channel switch if still in process
         */
-       if (priv->switch_rxon.switch_in_progress &&
-           (priv->switch_rxon.channel != ctx->staging.channel)) {
+       if (test_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status) &&
+           (priv->switch_channel != ctx->staging.channel)) {
                IWL_DEBUG_11H(priv, "abort channel switch on %d\n",
-                     le16_to_cpu(priv->switch_rxon.channel));
+                     le16_to_cpu(priv->switch_channel));
                iwl_legacy_chswitch_done(priv, false);
        }
 
@@ -1404,9 +1404,6 @@ static int iwl4965_hw_channel_switch(struct iwl_priv *priv,
                return rc;
        }
 
-       priv->switch_rxon.channel = cmd.channel;
-       priv->switch_rxon.switch_in_progress = true;
-
        return iwl_legacy_send_cmd_pdu(priv,
                         REPLY_CHANNEL_SWITCH, sizeof(cmd), &cmd);
 }

diff --git a/drivers/net/wireless/iwlegacy/iwl-core.c b/drivers/net/wireless/iwlegacy/iwl-core.c
index 42df832..3be76bd 100644 (file)
--- a/drivers/net/wireless/iwlegacy/iwl-core.c
+++ b/drivers/net/wireless/iwlegacy/iwl-core.c
@@ -859,12 +859,8 @@ void iwl_legacy_chswitch_done(struct iwl_priv *priv, bool is_success)
        if (test_bit(STATUS_EXIT_PENDING, &priv->status))
                return;
 
-       if (priv->switch_rxon.switch_in_progress) {
+       if (test_and_clear_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status))
                ieee80211_chswitch_done(ctx->vif, is_success);
-               mutex_lock(&priv->mutex);
-               priv->switch_rxon.switch_in_progress = false;
-               mutex_unlock(&priv->mutex);
-       }
 }
 EXPORT_SYMBOL(iwl_legacy_chswitch_done);
 
@@ -876,19 +872,19 @@ void iwl_legacy_rx_csa(struct iwl_priv *priv, struct iwl_rx_mem_buffer *rxb)
        struct iwl_rxon_context *ctx = &priv->contexts[IWL_RXON_CTX_BSS];
        struct iwl_legacy_rxon_cmd *rxon = (void *)&ctx->active;
 
-       if (priv->switch_rxon.switch_in_progress) {
-               if (!le32_to_cpu(csa->status) &&
-                   (csa->channel == priv->switch_rxon.channel)) {
-                       rxon->channel = csa->channel;
-                       ctx->staging.channel = csa->channel;
-                       IWL_DEBUG_11H(priv, "CSA notif: channel %d\n",
-                             le16_to_cpu(csa->channel));
-                       iwl_legacy_chswitch_done(priv, true);
-               } else {
-                       IWL_ERR(priv, "CSA notif (fail) : channel %d\n",
+       if (!test_bit(STATUS_CHANNEL_SWITCH_PENDING, &priv->status))
+               return;
+
+       if (!le32_to_cpu(csa->status) && csa->channel == priv->switch_channel) {
+               rxon->channel = csa->channel;
+               ctx->staging.channel = csa->channel;
+               IWL_DEBUG_11H(priv, "CSA notif: channel %d\n",
                              le16_to_cpu(csa->channel));
-                       iwl_legacy_chswitch_done(priv, false);
-               }
+               iwl_legacy_chswitch_done(priv, true);
+       } else {
+               IWL_ERR(priv, "CSA notif (fail) : channel %d\n",
+                       le16_to_cpu(csa->channel));
+               iwl_legacy_chswitch_done(priv, false);
        }
 }
 EXPORT_SYMBOL(iwl_legacy_rx_csa);

diff --git a/drivers/net/wireless/iwlegacy/iwl-core.h b/drivers/net/wireless/iwlegacy/iwl-core.h
index bc66c60..c5fbda0 100644 (file)
--- a/drivers/net/wireless/iwlegacy/iwl-core.h
+++ b/drivers/net/wireless/iwlegacy/iwl-core.h
@@ -560,7 +560,7 @@ void iwl_legacy_free_geos(struct iwl_priv *priv);
 #define STATUS_SCAN_HW         15
 #define STATUS_POWER_PMI       16
 #define STATUS_FW_ERROR                17
-
+#define STATUS_CHANNEL_SWITCH_PENDING 18
 
 static inline int iwl_legacy_is_ready(struct iwl_priv *priv)
 {

diff --git a/drivers/net/wireless/iwlegacy/iwl-dev.h b/drivers/net/wireless/iwlegacy/iwl-dev.h
index be0106c..ea30122 100644 (file)
--- a/drivers/net/wireless/iwlegacy/iwl-dev.h
+++ b/drivers/net/wireless/iwlegacy/iwl-dev.h
@@ -855,17 +855,6 @@ struct traffic_stats {
 };
 
 /*
- * iwl_switch_rxon: "channel switch" structure
- *
- * @ switch_in_progress: channel switch in progress
- * @ channel: new channel
- */
-struct iwl_switch_rxon {
-       bool switch_in_progress;
-       __le16 channel;
-};
-
-/*
  * schedule the timer to wake up every UCODE_TRACE_PERIOD milliseconds
  * to perform continuous uCode event logging operation if enabled
  */
@@ -1115,7 +1104,7 @@ struct iwl_priv {
 
        struct iwl_rxon_context contexts[NUM_IWL_RXON_CTX];
 
-       struct iwl_switch_rxon switch_rxon;
+       __le16 switch_channel;
 
        /* 1st responses from initialize and runtime uCode images.
         * _4965's initialize alive response contains some calibration data. */

diff --git a/drivers/net/wireless/iwlegacy/iwl4965-base.c b/drivers/net/wireless/iwlegacy/iwl4965-base.c
index af2ae22..7157ba5 100644 (file)
--- 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");
 }