On Wed, Apr 14, 2010 at 09:00:57AM -0700, Paul E. McKenney wrote:
> On Wed, Apr 14, 2010 at 05:51:11PM +0200, Frederic Weisbecker wrote:
[ . . .]
> > Note I just tested the patch the previous one and it looks fine now.
> > You can then safely consider the "general idea" fixes the problem :)
>
> Thank you, Frederic!!!
And here is what I hope is the official fix.
Could you please test it?
Thanx, Paul
------------------------------------------------------------------------
commit 9be39c445a41e458d53cf9a57d25dbfa4b74c970
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Date: Tue Apr 13 18:45:51 2010 -0700
rcu: Make RCU lockdep check the lockdep_recursion variable
The lockdep facility temporarily disables lockdep checking by incrementing
the current->lockdep_recursion variable. Such disabling happens in NMIs
and in other situations where lockdep might expect to recurse on itself.
This patch therefore checks current->lockdep_recursion, disabling RCU
lockdep splats when this variable is non-zero. In addition, this patch
removes the "likely()", as suggested by Lai Jiangshan.
Reported-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Reported-by: David Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 9f1ddfe..07db2fe 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -101,10 +101,7 @@ extern struct lockdep_map rcu_sched_lock_map;
# define rcu_read_release_sched() \
lock_release(&rcu_sched_lock_map, 1, _THIS_IP_)
-static inline int debug_lockdep_rcu_enabled(void)
-{
- return likely(rcu_scheduler_active && debug_locks);
-}
+extern int debug_lockdep_rcu_enabled(void);
/**
* rcu_read_lock_held - might we be in RCU read-side critical section?
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index 63fe254..03a7ea1 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -69,6 +69,13 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
+int debug_lockdep_rcu_enabled(void)
+{
+ return rcu_scheduler_active && debug_locks &&
+ current->lockdep_recursion == 0;
+}
+EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
+
/**
* rcu_read_lock_bh_held - might we be in RCU-bh read-side critical section?
*
--
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