On Sat, 2008-10-04 at 05:31 -0500, Robin Holt wrote:
> I have been ignoring a hang/pause on my machine running an iwl3945
> adapter following a suspend/resume cycle. I finally decided to start
> hunting it down. This started with an Ubuntu kernel update to the Ubuntu
> 8.04 dist. I don't recall seeing the hangs when I was running 7.10.
> It continued when I was testing the community 2.6.27-rc1-8 kernels.
> KDB helped me track it to one cpu's event thread infinitely looping.
[...]
> This resulted in dmesg output of:
> 656: Got sta = 0xef747270, stations = 0x0
> 658: Got sta = 0xef747270, debugfs.dir = 0x0
> 662: Got sta = 0x0
> 656: Got sta = 0xef747270, stations = 0x0
> 658: Got sta = 0xef747270, debugfs.dir = 0x0
> 662: Got sta = 0x0
> 656: Got sta = 0xef747270, stations = 0x0
> 658: Got sta = 0xef747270, debugfs.dir = 0x0
> 662: Got sta = 0x0
> 656: Got sta = 0xef747270, stations = 0x0
> 658: Got sta = 0xef747270, debugfs.dir = 0x0
> 662: Got sta = 0x0
>
> I made up the 0xef747270 as the battery died before I had it written
> down. The idea is correct even if the address is not.
>
> I have no idea what this code is trying to accomplish. I assume it is
> not corrrectly handling the case where sta->local->debugfs.stations is
> NULL.
The code's trying to add debugfs entries for all STAs that don't have
any yet. I suspect that maybe you don't have debugfs configured into
your kernel or something is wrong; anyway, the code is really abusing
the debugfs.dir as a flag "need to run ieee80211_sta_debugfs_add"; the
problem is that ieee80211_sta_debugfs_add() doesn't necessarily set
debugfs.dir to != NULL under all circumstances.
I think we'll have to add a flag, do you have a way to reproduce this?
Can you try this patch?
johannes
--- everything.orig/net/mac80211/debugfs_sta.c 2008-10-05 02:16:51.000000000 +0200
+++ everything/net/mac80211/debugfs_sta.c 2008-10-05 02:17:06.000000000 +0200
@@ -249,6 +249,8 @@ void ieee80211_sta_debugfs_add(struct st
DECLARE_MAC_BUF(mbuf);
u8 *mac;
+ sta->debugfs.add_has_run = true;
+
if (!stations_dir)
return;
--- everything.orig/net/mac80211/sta_info.c 2008-10-05 02:16:06.000000000 +0200
+++ everything/net/mac80211/sta_info.c 2008-10-05 02:18:12.000000000 +0200
@@ -635,7 +635,12 @@ static void sta_info_debugfs_add_work(st
spin_lock_irqsave(&local->sta_lock, flags);
list_for_each_entry(tmp, &local->sta_list, list) {
- if (!tmp->debugfs.dir) {
+ /*
+ * debugfs.add_has_run will be set by
+ * ieee80211_sta_debugfs_add regardless
+ * of what else it does.
+ */
+ if (!tmp->debugfs.add_has_run) {
sta = tmp;
__sta_info_pin(sta);
break;
--- everything.orig/net/mac80211/sta_info.h 2008-10-05 02:16:09.000000000 +0200
+++ everything/net/mac80211/sta_info.h 2008-10-05 02:17:13.000000000 +0200
@@ -312,6 +312,7 @@ struct sta_info {
struct dentry *wme_tx_queue;
#endif
struct dentry *agg_status;
+ bool add_has_run;
} debugfs;
#endif
--
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
