This is a note to let you know that I've just added the patch titled

    iwlegacy: fix channel switch locking

to the 2.6.39-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     iwlegacy-fix-channel-switch-locking.patch
and it can be found in the queue-2.6.39 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.


>From 51e65257142a87fe46a1ce5c35c86c5baf012614 Mon Sep 17 00:00:00 2001
From: Stanislaw Gruszka <[email protected]>
Date: Wed, 8 Jun 2011 15:26:31 +0200
Subject: iwlegacy: fix channel switch locking

From: Stanislaw Gruszka <[email protected]>

commit 51e65257142a87fe46a1ce5c35c86c5baf012614 upstream.

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.

Signed-off-by: Stanislaw Gruszka <[email protected]>
Signed-off-by: John W. Linville <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/net/wireless/iwlegacy/iwl-4965.c     |    9 ++------
 drivers/net/wireless/iwlegacy/iwl-core.c     |   30 +++++++++++----------------
 drivers/net/wireless/iwlegacy/iwl-core.h     |    2 -
 drivers/net/wireless/iwlegacy/iwl-dev.h      |   13 -----------
 drivers/net/wireless/iwlegacy/iwl4965-base.c |   19 +++++++++--------
 5 files changed, 28 insertions(+), 45 deletions(-)

--- 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 iw
         * 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(str
                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);
 }
--- a/drivers/net/wireless/iwlegacy/iwl-core.c
+++ b/drivers/net/wireless/iwlegacy/iwl-core.c
@@ -862,12 +862,8 @@ void iwl_legacy_chswitch_done(struct iwl
        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);
 
@@ -879,19 +875,19 @@ void iwl_legacy_rx_csa(struct iwl_priv *
        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);
--- a/drivers/net/wireless/iwlegacy/iwl-core.h
+++ b/drivers/net/wireless/iwlegacy/iwl-core.h
@@ -561,7 +561,7 @@ void iwl_legacy_free_geos(struct iwl_pri
 #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)
 {
--- a/drivers/net/wireless/iwlegacy/iwl-dev.h
+++ b/drivers/net/wireless/iwlegacy/iwl-dev.h
@@ -854,17 +854,6 @@ 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. */
--- a/drivers/net/wireless/iwlegacy/iwl4965-base.c
+++ b/drivers/net/wireless/iwlegacy/iwl4965-base.c
@@ -2851,16 +2851,13 @@ void iwl4965_mac_channel_switch(struct i
                goto out_exit;
 
        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_exit;
 
        if (!iwl_legacy_is_associated_ctx(ctx))
                goto out_exit;
 
-       /* channel switch in progress */
-       if (priv->switch_rxon.switch_in_progress == true)
-               goto out_exit;
-
        mutex_lock(&priv->mutex);
        if (priv->cfg->ops->lib->set_channel_switch) {
 
@@ -2910,16 +2907,20 @@ void iwl4965_mac_channel_switch(struct i
                         * at this point, staging_rxon has the
                         * configuration for channel switch
                         */
+                       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))
-                               priv->switch_rxon.switch_in_progress = false;
+                                                                   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);
 out_exit:
-       if (!priv->switch_rxon.switch_in_progress)
-               ieee80211_chswitch_done(ctx->vif, false);
        IWL_DEBUG_MAC80211(priv, "leave\n");
 }
 


Patches currently in stable-queue which might be from [email protected] are

queue-2.6.39/iwlagn-use-cts-to-self-protection-on-5000-adapters-series.patch
queue-2.6.39/iwl4965-fix-5ghz-operation.patch
queue-2.6.39/iwl4965-correctly-validate-temperature-value.patch
queue-2.6.39/iwlegacy-fix-channel-switch-locking.patch
queue-2.6.39/iwl4965-set-tx-power-after-rxon_assoc.patch
queue-2.6.39/iwlagn-fix-channel-switch-locking.patch
queue-2.6.39/iwlagn-send-tx-power-command-if-defer-cause-by-rxon-not.patch

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