68 lines
2.3 KiB
Diff
68 lines
2.3 KiB
Diff
Subject: mac80211: fix debugfs lockup
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When debugfs_create_dir fails, sta_info_debugfs_add_work will not
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terminate because it will find the same station again and again.
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This is possible whenever debugfs fails for whatever reason; one
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reason is a race condition in mac80211, unfortunately we cannot
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do much about it, so just document it, it just means some station
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may be missing from debugfs.
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Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
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Cc: Robin Holt <holt@sgi.com>
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---
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net/mac80211/debugfs_sta.c | 11 +++++++++++
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net/mac80211/sta_info.c | 7 ++++++-
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net/mac80211/sta_info.h | 1 +
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3 files changed, 18 insertions(+), 1 deletion(-)
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--- everything.orig/net/mac80211/debugfs_sta.c 2008-10-07 20:05:29.000000000 +0200
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+++ everything/net/mac80211/debugfs_sta.c 2008-10-07 20:06:39.000000000 +0200
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@@ -249,11 +249,22 @@ void ieee80211_sta_debugfs_add(struct st
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DECLARE_MAC_BUF(mbuf);
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u8 *mac;
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+ sta->debugfs.add_has_run = true;
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+
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if (!stations_dir)
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return;
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mac = print_mac(mbuf, sta->sta.addr);
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+ /*
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+ * This might fail due to a race condition:
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+ * When mac80211 unlinks a station, the debugfs entries
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+ * remain, but it is already possible to link a new
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+ * station with the same address which triggers adding
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+ * it to debugfs; therefore, if the old station isn't
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+ * destroyed quickly enough the old station's debugfs
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+ * dir might still be around.
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+ */
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sta->debugfs.dir = debugfs_create_dir(mac, stations_dir);
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if (!sta->debugfs.dir)
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return;
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--- everything.orig/net/mac80211/sta_info.c 2008-10-07 20:05:29.000000000 +0200
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+++ everything/net/mac80211/sta_info.c 2008-10-07 20:06:39.000000000 +0200
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@@ -635,7 +635,12 @@ static void sta_info_debugfs_add_work(st
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spin_lock_irqsave(&local->sta_lock, flags);
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list_for_each_entry(tmp, &local->sta_list, list) {
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- if (!tmp->debugfs.dir) {
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+ /*
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+ * debugfs.add_has_run will be set by
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+ * ieee80211_sta_debugfs_add regardless
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+ * of what else it does.
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+ */
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+ if (!tmp->debugfs.add_has_run) {
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sta = tmp;
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__sta_info_pin(sta);
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break;
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--- everything.orig/net/mac80211/sta_info.h 2008-10-07 20:05:29.000000000 +0200
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+++ everything/net/mac80211/sta_info.h 2008-10-07 20:06:39.000000000 +0200
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@@ -300,6 +300,7 @@ struct sta_info {
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struct dentry *inactive_ms;
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struct dentry *last_seq_ctrl;
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struct dentry *agg_status;
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+ bool add_has_run;
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} debugfs;
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#endif
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