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Subject[89/89] iwlegacy: fix channel switch locking
2.6.39-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Stanislaw Gruszka <sgruszka@redhat.com>

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 <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
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");
}




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