On 05/02/2012 12:07 PM, Johannes Berg wrote:
On Wed, 2012-05-02 at 11:00 +0100, Catalin Marinas wrote:
Your patch does not help. I still get the following dump in the log:
The patch is also wrong, we hold the mutex there and can't hold RCU read
lock.
#0: (scan_mutex){+.+...}, at: [<ffffffff8113b0d6>] kmemleak_scan_thread+0x56/0xd0
#1: (&tid_tx->session_timer){+.-...}, at: [<ffffffff8104853a>]
run_timer_softirq+0xfa/0x6e0
#2: (rcu_read_lock){.+.+..}, at: [<ffffffffa0449ff0>]
sta_tx_agg_session_timer_expired+0x0/0x2a0 [mac80211]
stack backtrace:
Pid: 622, comm: kmemleak Not tainted 3.4.0-rc5-wl+ #287
Call Trace:
<IRQ> [<ffffffff8109309d>] lockdep_rcu_suspicious+0xfd/0x130
[<ffffffffa044a1cf>] sta_tx_agg_session_timer_expired+0x1df/0x2a0 [mac80211]
[<ffffffffa0449ff0>] ? ieee80211_start_tx_ba_session+0x450/0x450 [mac80211]
[<ffffffff810485c5>] run_timer_softirq+0x185/0x6e0
As kmemleak seems to be involved, I have added Catalin Marinas to the Cc list.
Looking at the code and the logs, ieee80211_start_tx_ba_session() calls
I'm almost certain that ieee80211_start_tx_ba_session() is a bogus
calltrace entry, since we're in a timer and that's not called from a
timer.
rcu_dereference_protected_tid_tx() which calls
rcu_dereference_protected() with the (lockdep_is_held(&sta->lock) ||
lockdep_is_held(&sta->ampdu_mlme.mtx)) condition which is false. As the
kernel log says, none of these locks are held, hence the warning.
So does that just mean we need to add rcu_read_lock_held() to the
conditions? I thought that wasn't necessary? +Paul.
If you meant the following
Index: wireless-testing-new/net/mac80211/sta_info.h
===================================================================
--- wireless-testing-new.orig/net/mac80211/sta_info.h
+++ wireless-testing-new/net/mac80211/sta_info.h
@@ -453,7 +453,8 @@ rcu_dereference_protected_tid_tx(struct
{
return rcu_dereference_protected(sta->ampdu_mlme.tid_tx[tid],
lockdep_is_held(&sta->lock) ||
- lockdep_is_held(&sta->ampdu_mlme.mtx));
+ lockdep_is_held(&sta->ampdu_mlme.mtx) ||
+ rcu_read_lock_held());
}
#define STA_HASH_SIZE 256
It does not help.
Larry
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