Hi Gruszka, On Wed, 2010-07-28 at 06:45 -0700, Stanislaw Gruszka wrote: > 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)); make sense here, the code is broken, we should not abort scan if already doing it. > > 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); > } Looks right to me, thanks a lot to catch this one. Wey -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html