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>
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3 changed files with 6 additions and 17 deletions
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@ -669,13 +669,6 @@ static int iwl_set_mode(struct iwl_priv *priv, int mode)
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if (!iwl_is_ready_rf(priv))
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return -EAGAIN;
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cancel_delayed_work(&priv->scan_check);
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if (iwl_scan_cancel_timeout(priv, 100)) {
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IWL_WARN(priv, "Aborted scan still in progress after 100ms\n");
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IWL_DEBUG_MAC80211(priv, "leaving - scan abort failed.\n");
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return -EAGAIN;
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}
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iwl_commit_rxon(priv);
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return 0;
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@ -227,9 +227,6 @@ static void iwl_rx_scan_complete_notif(struct iwl_priv *priv,
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/* The HW is no longer scanning */
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clear_bit(STATUS_SCAN_HW, &priv->status);
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/* The scan completion notification came in, so kill that timer... */
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cancel_delayed_work(&priv->scan_check);
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IWL_DEBUG_INFO(priv, "Scan pass on %sGHz took %dms\n",
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(priv->scan_bands & BIT(IEEE80211_BAND_2GHZ)) ?
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"2.4" : "5.2",
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@ -712,6 +709,8 @@ static void iwl_bg_request_scan(struct work_struct *data)
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mutex_lock(&priv->mutex);
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cancel_delayed_work(&priv->scan_check);
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if (!iwl_is_ready(priv)) {
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IWL_WARN(priv, "request scan called when driver not ready.\n");
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goto done;
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@ -925,6 +924,8 @@ void iwl_bg_scan_completed(struct work_struct *work)
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IWL_DEBUG_SCAN(priv, "SCAN complete scan\n");
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cancel_delayed_work(&priv->scan_check);
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ieee80211_scan_completed(priv->hw, false);
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if (test_bit(STATUS_EXIT_PENDING, &priv->status))
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@ -782,13 +782,6 @@ static int iwl3945_set_mode(struct iwl_priv *priv, int mode)
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if (!iwl_is_ready_rf(priv))
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return -EAGAIN;
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cancel_delayed_work(&priv->scan_check);
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if (iwl_scan_cancel_timeout(priv, 100)) {
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IWL_WARN(priv, "Aborted scan still in progress after 100ms\n");
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IWL_DEBUG_MAC80211(priv, "leaving - scan abort failed.\n");
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return -EAGAIN;
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}
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iwl3945_commit_rxon(priv);
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return 0;
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@ -3298,6 +3291,8 @@ static void iwl3945_bg_request_scan(struct work_struct *data)
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mutex_lock(&priv->mutex);
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cancel_delayed_work(&priv->scan_check);
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if (!iwl_is_ready(priv)) {
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IWL_WARN(priv, "request scan called when driver not ready.\n");
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goto done;
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