Subject: Re: [PATCH wireless-2.6 or stable] iwlwifi: return error when fail to start scanning

From: Florian Mickler <[email-masked]>
Date: Wed, 6 Oct 2010 19:45:37 +0200

Hi Stanislaw!

On Wed, 6 Oct 2010 18:04:35 +0200
Stanislaw Gruszka <[email-masked]> wrote:

> This is stable friendly backport of wireless-testing commit
> 3eecce527c7434dfd16517ce08b49632c8a26717 "iwlwifi: unify scan start
> checks". Wireless-testing version include also a lot of cleanups.
> 
> On error case in {iwl3945,iwlagn}_request_scan we queue abort_scan work,
> which in a fact do nothing, so we never complete the scan. Thats gives
> "WARNING: at net/wireless/core.c:614 wdev_cleanup_work" and stopped
> network connection until reload iwlwifi modules. Return of -EIO, and
> stopping queuing any work is a fix.
> 
> Note there are still many cases when we can get: 
> 
> WARNING: at net/wireless/core.c:614 wdev_cleanup_work  
> WARNING: at net/mac80211/scan.c:266 ieee80211_scan_completed
> WARNING: at net/mac80211/scan.c:269 ieee80211_scan_complete
> 
> which are not fixed. Unfortunately does not exist single, small fix
> for that problems, and we probably will see some more bug reports
> with scan warnings. As solution we rewrite iwl-scan.c code to avoid
> all possible race conditions. That quite big patch set is queued
> for 2.6.37 .
> 
> Signed-off-by: Stanislaw Gruszka <[email-masked]>
> ---

Not that it matters much, but I've looked through it and couldn't find
anything wrong with it.

 Reviewed-by: Florian Mickler <[email-masked]>

Regards,
Flo

> Patch is intended for wireless-2.6, or in case when it does not
> make 2.6.36 release, for -stable 2.6.36.y 
> 
>  drivers/net/wireless/iwlwifi/iwl-3945.h     |    2 +-
>  drivers/net/wireless/iwlwifi/iwl-agn-lib.c  |   18 ++++++------------
>  drivers/net/wireless/iwlwifi/iwl-agn.h      |    2 +-
>  drivers/net/wireless/iwlwifi/iwl-core.h     |    2 +-
>  drivers/net/wireless/iwlwifi/iwl-scan.c     |   14 +++++++++++---
>  drivers/net/wireless/iwlwifi/iwl3945-base.c |   19 ++++++-------------
>  6 files changed, 26 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/net/wireless/iwlwifi/iwl-3945.h b/drivers/net/wireless/iwlwifi/iwl-3945.h
> index bb2aeeb..98509c5 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-3945.h
> +++ b/drivers/net/wireless/iwlwifi/iwl-3945.h
> @@ -295,7 +295,7 @@ extern const struct iwl_channel_info *iwl3945_get_channel_info(
>  extern int iwl3945_rs_next_rate(struct iwl_priv *priv, int rate);
>  
>  /* scanning */
> -void iwl3945_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif);
> +int iwl3945_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif);
>  
>  /* Requires full declaration of iwl_priv before including */
>  #include "iwl-io.h"
> diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
> index 8fd00a6..2be8faa 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
> +++ b/drivers/net/wireless/iwlwifi/iwl-agn-lib.c
> @@ -1147,7 +1147,7 @@ static int iwl_get_channels_for_scan(struct iwl_priv *priv,
>  	return added;
>  }
>  
> -void iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
> +int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
>  {
>  	struct iwl_host_cmd cmd = {
>  		.id = REPLY_SCAN_CMD,
> @@ -1394,24 +1394,18 @@ void iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
>  	scan->len = cpu_to_le16(cmd.len);
>  
>  	set_bit(STATUS_SCAN_HW, &priv->status);
> -	if (iwl_send_cmd_sync(priv, &cmd))
> +	if (iwl_send_cmd_sync(priv, &cmd)) {
> +		clear_bit(STATUS_SCAN_HW, &priv->status);
>  		goto done;
> +	}
>  
>  	queue_delayed_work(priv->workqueue, &priv->scan_check,
>  			   IWL_SCAN_CHECK_WATCHDOG);
>  
> -	return;
> +	return 0;
>  
>   done:
> -	/* Cannot perform scan. Make sure we clear scanning
> -	* bits from status so next scan request can be performed.
> -	* If we don't clear scanning status bit here all next scan
> -	* will fail
> -	*/
> -	clear_bit(STATUS_SCAN_HW, &priv->status);
> -	clear_bit(STATUS_SCANNING, &priv->status);
> -	/* inform mac80211 scan aborted */
> -	queue_work(priv->workqueue, &priv->abort_scan);
> +	return -EIO;
>  }
>  
>  int iwlagn_manage_ibss_station(struct iwl_priv *priv,
> diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.h b/drivers/net/wireless/iwlwifi/iwl-agn.h
> index cc6464d..015da26 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-agn.h
> +++ b/drivers/net/wireless/iwlwifi/iwl-agn.h
> @@ -216,7 +216,7 @@ void iwl_reply_statistics(struct iwl_priv *priv,
>  			  struct iwl_rx_mem_buffer *rxb);
>  
>  /* scan */
> -void iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif);
> +int iwlagn_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif);
>  
>  /* station mgmt */
>  int iwlagn_manage_ibss_station(struct iwl_priv *priv,
> diff --git a/drivers/net/wireless/iwlwifi/iwl-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
> index 5e6ee3d..110de0f 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-core.h
> +++ b/drivers/net/wireless/iwlwifi/iwl-core.h
> @@ -109,7 +109,7 @@ struct iwl_hcmd_utils_ops {
>  				  __le16 fc, __le32 *tx_flags);
>  	int  (*calc_rssi)(struct iwl_priv *priv,
>  			  struct iwl_rx_phy_res *rx_resp);
> -	void (*request_scan)(struct iwl_priv *priv, struct ieee80211_vif *vif);
> +	int (*request_scan)(struct iwl_priv *priv, struct ieee80211_vif *vif);
>  };
>  
>  struct iwl_apm_ops {
> diff --git a/drivers/net/wireless/iwlwifi/iwl-scan.c b/drivers/net/wireless/iwlwifi/iwl-scan.c
> index a4b3663..290140a 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-scan.c
> +++ b/drivers/net/wireless/iwlwifi/iwl-scan.c
> @@ -298,6 +298,7 @@ EXPORT_SYMBOL(iwl_init_scan_params);
>  
>  static int iwl_scan_initiate(struct iwl_priv *priv, struct ieee80211_vif *vif)
>  {
> +	int ret;
>  	lockdep_assert_held(&priv->mutex);
>  
>  	IWL_DEBUG_INFO(priv, "Starting scan...\n");
> @@ -308,9 +309,11 @@ static int iwl_scan_initiate(struct iwl_priv *priv, struct ieee80211_vif *vif)
>  	if (WARN_ON(!priv->cfg->ops->utils->request_scan))
>  		return -EOPNOTSUPP;
>  
> -	priv->cfg->ops->utils->request_scan(priv, vif);
> +	ret = priv->cfg->ops->utils->request_scan(priv, vif);
> +	if (ret)
> +		clear_bit(STATUS_SCANNING, &priv->status);
> +	return ret;
>  
> -	return 0;
>  }
>  
>  int iwl_mac_hw_scan(struct ieee80211_hw *hw,
> @@ -380,6 +383,7 @@ void iwl_internal_short_hw_scan(struct iwl_priv *priv)
>  
>  void iwl_bg_start_internal_scan(struct work_struct *work)
>  {
> +	int ret;
>  	struct iwl_priv *priv =
>  		container_of(work, struct iwl_priv, start_internal_scan);
>  
> @@ -414,7 +418,11 @@ void iwl_bg_start_internal_scan(struct work_struct *work)
>  	if (WARN_ON(!priv->cfg->ops->utils->request_scan))
>  		goto unlock;
>  
> -	priv->cfg->ops->utils->request_scan(priv, NULL);
> +	ret = priv->cfg->ops->utils->request_scan(priv, NULL);
> +	if (ret) {
> +		clear_bit(STATUS_SCANNING, &priv->status);
> +		priv->is_internal_short_scan = false;
> +	}
>   unlock:
>  	mutex_unlock(&priv->mutex);
>  }
> diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
> index d31661c..fc82da0 100644
> --- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
> +++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
> @@ -2799,7 +2799,7 @@ static void iwl3945_rfkill_poll(struct work_struct *data)
>  
>  }
>  
> -void iwl3945_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
> +int iwl3945_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
>  {
>  	struct iwl_host_cmd cmd = {
>  		.id = REPLY_SCAN_CMD,
> @@ -3000,25 +3000,18 @@ void iwl3945_request_scan(struct iwl_priv *priv, struct ieee80211_vif *vif)
>  	scan->len = cpu_to_le16(cmd.len);
>  
>  	set_bit(STATUS_SCAN_HW, &priv->status);
> -	if (iwl_send_cmd_sync(priv, &cmd))
> +	if (iwl_send_cmd_sync(priv, &cmd)) {
> +		clear_bit(STATUS_SCAN_HW, &priv->status);
>  		goto done;
> +	}
>  
>  	queue_delayed_work(priv->workqueue, &priv->scan_check,
>  			   IWL_SCAN_CHECK_WATCHDOG);
>  
> -	return;
> +	return 0;
>  
>   done:
> -	/* can not perform scan make sure we clear scanning
> -	 * bits from status so next scan request can be performed.
> -	 * if we dont clear scanning status bit here all next scan
> -	 * will fail
> -	*/
> -	clear_bit(STATUS_SCAN_HW, &priv->status);
> -	clear_bit(STATUS_SCANNING, &priv->status);
> -
> -	/* inform mac80211 scan aborted */
> -	queue_work(priv->workqueue, &priv->abort_scan);
> +	return -EIO;
>  }
>  
>  static void iwl3945_bg_restart(struct work_struct *data)
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