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iwlwifi: fix scan abort

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Fix possible double priv->mutex lock introduced by commit
a69b03e941
"iwlwifi: cancel scan watchdog in iwl_bg_abort_scan" .
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.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
CC: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Stanislaw Gruszka 2010-07-29 11:37:41 +02:00 committed by John W. Linville
parent 16345910d9
commit d28232b461
1 changed files with 8 additions and 10 deletions
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18
drivers/net/wireless/iwlwifi/iwl-scan.c
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@ -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;
cancel_delayed_work(&priv->scan_check);
mutex_lock(&priv->mutex);
cancel_delayed_work_sync(&priv->scan_check);
set_bit(STATUS_SCAN_ABORTING, &priv->status);
iwl_send_scan_abort(priv);
if (test_bit(STATUS_SCAN_ABORTING, &priv->status))
iwl_send_scan_abort(priv);
mutex_unlock(&priv->mutex);
}
EXPORT_SYMBOL(iwl_bg_abort_scan);