[PATCH tip/core/rcu 4/4] rcu: add control variables to lockdep_rcu_dereference() diagnostics

From: Paul E. McKenney
Date: Wed Mar 03 2010 - 10:48:04 EST

Add the values of rcu_scheduler_active() and debug_locks() to the
lockdep_rcu_dereference() output to help diagnose RCU lockdep splats
that occur shortly after the scheduler starts.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
kernel/lockdep.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 0c30d04..681bc2e 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -3822,6 +3822,7 @@ void lockdep_rcu_dereference(const char *file, const int line)
printk("%s:%d invoked rcu_dereference_check() without protection!\n",
file, line);
printk("\nother info that might help us debug this:\n\n");
+ printk("\nrcu_scheduler_active = %d, debug_locks = %d\n", rcu_scheduler_active, debug_locks);
printk("\nstack backtrace:\n");

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