I found a regression where my EEE hangs at boot time, if the battery is
present.
I'm confident it's a regression because it disappears if I revert
Arjan's asynchronous battery initialisation. However, the evidence
points to a deadlock in the wireless stack which has simply been
uncovered by timing changes.
If I leave the system long enough, I get a series of hung task
warnings. They suggest the following deadlock:
- ieee80211_wep_init(), which is called with rtnl_lock() held, is
blocked in request_module() [waiting for modprobe to load a crypto module].
- modprobe is blocked in a call to flush_workqueue(), caused by closing
a TTY.
- worker_thread is blocked because the workqueue item linkwatch_event()
is blocked on rtnl_lock.
I've hacked up a test patch to move wep_init() outside of rtnl_lock, and
it solved the problem. My one caveat is that it would probably be
cleaner to move it after rtnl_unlock(), instead of before rtnl_lock().
I just wasn't 100% sure if that would be safe. Here's the patch:
---8<---
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index fbcbed6..fffa7f9 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -909,6 +909,13 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
if (result < 0)
goto fail_sta_info;
+ result = ieee80211_wep_init(local);
+ if (result < 0) {
+ printk(KERN_DEBUG "%s: Failed to initialize wep: %d\n",
+ wiphy_name(local->hw.wiphy), result);
+ goto fail_wep;
+ }
+
rtnl_lock();
result = dev_alloc_name(local->mdev, local->mdev->name);
if (result < 0)
@@ -930,14 +937,6 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
goto fail_rate;
}
- result = ieee80211_wep_init(local);
-
- if (result < 0) {
- printk(KERN_DEBUG "%s: Failed to initialize wep: %d\n",
- wiphy_name(local->hw.wiphy), result);
- goto fail_wep;
- }
-
/* add one default STA interface if supported */
if (local->hw.wiphy->interface_modes & BIT(NL80211_IFTYPE_STATION)) {
result = ieee80211_if_add(local, "wlan%d", NULL,
@@ -967,13 +966,12 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
return 0;
-fail_wep:
- rate_control_deinitialize(local);
fail_rate:
unregister_netdevice(local->mdev);
local->mdev = NULL;
fail_dev:
rtnl_unlock();
+fail_wep:
sta_info_stop(local);
fail_sta_info:
debugfs_hw_del(local);
--
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