From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:55655 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751894Ab0G1Npg (ORCPT ); Wed, 28 Jul 2010 09:45:36 -0400 Date: Wed, 28 Jul 2010 15:45:09 +0200 From: Stanislaw Gruszka To: Wey-Yi Guy , Reinette Chatre , "John W. Linville" Cc: linux-wireless@vger.kernel.org Subject: [RFC] iwlwifi: fix scan abort Message-ID: <20100728154509.77e8e85b@dhcp-lab-109.englab.brq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-wireless-owner@vger.kernel.org List-ID: We can not call cancel_delayed_work_sync(&priv->scan_check) with priv->mutex locked because workqueue function iwl_bg_scan_check() take that lock internally. We do not need to synchronize when canceling priv->scan_check work. We can avoid races (sending double abort command or send no command at all) using STATUS_SCAN_ABORT bit. Moreover current iwl_bg_scan_check() code seems to be broken, as we should not send abort commands when currently aborting. I did not test patch yet, just want to know if it is theoretically correct. Except obvious circular priv->mutex locking fix, maybe it can help with warning in ieee80211_scan_completed, which is still reported by the users from time to time. diff --git a/drivers/net/wireless/iwlwifi/iwl-scan.c b/drivers/net/wireless/iwlwifi/iwl-scan.c index 2a7c399..b0c6b04 100644 --- a/drivers/net/wireless/iwlwifi/iwl-scan.c +++ b/drivers/net/wireless/iwlwifi/iwl-scan.c @@ -429,11 +429,10 @@ void iwl_bg_scan_check(struct work_struct *data) return; mutex_lock(&priv->mutex); - if (test_bit(STATUS_SCANNING, &priv->status) || - test_bit(STATUS_SCAN_ABORTING, &priv->status)) { - IWL_DEBUG_SCAN(priv, "Scan completion watchdog resetting " - "adapter (%dms)\n", - jiffies_to_msecs(IWL_SCAN_CHECK_WATCHDOG)); + if (test_bit(STATUS_SCANNING, &priv->status) && + !test_bit(STATUS_SCAN_ABORTING, &priv->status)) { + IWL_DEBUG_SCAN(priv, "Scan completion watchdog (%dms)\n", + jiffies_to_msecs(IWL_SCAN_CHECK_WATCHDOG)); if (!test_bit(STATUS_EXIT_PENDING, &priv->status)) iwl_send_scan_abort(priv); @@ -498,12 +497,11 @@ void iwl_bg_abort_scan(struct work_struct *work) !test_bit(STATUS_GEO_CONFIGURED, &priv->status)) return; - mutex_lock(&priv->mutex); - - cancel_delayed_work_sync(&priv->scan_check); - set_bit(STATUS_SCAN_ABORTING, &priv->status); - iwl_send_scan_abort(priv); + cancel_delayed_work(&priv->scan_check); + mutex_lock(&priv->mutex); + if (test_bit(STATUS_SCAN_ABORTING, &priv->status)) + iwl_send_scan_abort(priv); mutex_unlock(&priv->mutex); } EXPORT_SYMBOL(iwl_bg_abort_scan);