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authorReinette Chatre <reinette.chatre@intel.com>2009-05-15 16:13:46 -0700
committerJohn W. Linville <linville@tuxdriver.com>2009-05-20 14:29:53 -0400
commitfbc9f97bbf5e1eaee562eba93dc60faaff3f3bfa (patch)
treeb9ee621a651efb7f8daeed55210106f2466daae5 /drivers/net/wireless/iwlwifi/iwl-scan.c
parenta54be5d43aa2d6febc5a4f8dd3b87b9429b60437 (diff)
iwlwifi: do not cancel delayed work inside spin_lock_irqsave
Calling cancel_delayed_work() from inside spin_lock_irqsave, introduces a potential deadlock. As explained by Johannes Berg <johannes@sipsolutions.net> A - lock T - timer phase CPU 1 CPU 2 --------------------------------------------- some place that calls cancel_timer_sync() (which is the | code) lock-irq(A) | "lock-irq"(T) | "unlock"(T) | wait(T) unlock(A) timer softirq "lock"(T) run(T) "unlock"(T) irq handler lock(A) unlock(A) Now all that again, interleaved, leading to deadlock: lock-irq(A) "lock"(T) run(T) IRQ during or maybe before run(T) --> lock(A) "lock-irq"(T) wait(T) We fix this by moving the call to cancel_delayed_work() into workqueue. There are cases where the work may not actually be queued or running at the time we are trying to cancel it, but cancel_delayed_work() is able to deal with this. Also cleanup iwl_set_mode related to this call. This function (iwl_set_mode) is only called when bringing interface up and there will thus not be any scanning done. No need to try to cancel scanning. Fixes http://bugzilla.kernel.org/show_bug.cgi?id=13224, which was also reported at http://marc.info/?l=linux-wireless&m=124081921903223&w=2 . Tested-by: Miles Lane <miles.lane@gmail.com> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Acked-by: Zhu Yi <yi.zhu@intel.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
Diffstat (limited to 'drivers/net/wireless/iwlwifi/iwl-scan.c')
-rw-r--r--drivers/net/wireless/iwlwifi/iwl-scan.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/net/wireless/iwlwifi/iwl-scan.c b/drivers/net/wireless/iwlwifi/iwl-scan.c
index e7c65c4f741b..6330b91e37ce 100644
--- a/drivers/net/wireless/iwlwifi/iwl-scan.c
+++ b/drivers/net/wireless/iwlwifi/iwl-scan.c
@@ -227,9 +227,6 @@ static void iwl_rx_scan_complete_notif(struct iwl_priv *priv,
/* The HW is no longer scanning */
clear_bit(STATUS_SCAN_HW, &priv->status);
- /* The scan completion notification came in, so kill that timer... */
- cancel_delayed_work(&priv->scan_check);
-
IWL_DEBUG_INFO(priv, "Scan pass on %sGHz took %dms\n",
(priv->scan_bands & BIT(IEEE80211_BAND_2GHZ)) ?
"2.4" : "5.2",
@@ -712,6 +709,8 @@ static void iwl_bg_request_scan(struct work_struct *data)
mutex_lock(&priv->mutex);
+ cancel_delayed_work(&priv->scan_check);
+
if (!iwl_is_ready(priv)) {
IWL_WARN(priv, "request scan called when driver not ready.\n");
goto done;
@@ -925,6 +924,8 @@ void iwl_bg_scan_completed(struct work_struct *work)
IWL_DEBUG_SCAN(priv, "SCAN complete scan\n");
+ cancel_delayed_work(&priv->scan_check);
+
ieee80211_scan_completed(priv->hw, false);
if (test_bit(STATUS_EXIT_PENDING, &priv->status))