Paul and Ingo,
Should we just remove the upper limit check, or is something like this
patch sound?
-- Steve
When DEBUG_KERNEL is set, place an upper bound limit on the rcu read
lock set to 100. If we go that deep, then a warn on will print.
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Index: linux-2.6.23-rc1-rt7/kernel/rcupreempt.c
===================================================================
--- linux-2.6.23-rc1-rt7.orig/kernel/rcupreempt.c 2007-08-05 11:25:38.000000000 -0400
+++ linux-2.6.23-rc1-rt7/kernel/rcupreempt.c 2007-08-05 11:30:33.000000000 -0400
@@ -50,6 +50,14 @@
#include <linux/cpumask.h>
#include <linux/rcupreempt_trace.h>
+#ifdef CONFIG_DEBUG_KERNEL
+/* Picking 100 as a high enough limit on rcu read lock nesting. */
+# define rcu_read_lock_check_upper_limit() \
+ WARN_ON_ONCE(current->rcu_read_lock_nesting > 100);
+#else
+# define rcu_read_lock_check_upper_limit() do { } while(0)
+#endif
+
/*
* PREEMPT_RCU data structures.
*/
@@ -129,9 +137,9 @@ void __rcu_read_lock(void)
atomic_inc(current->rcu_flipctr2);
smp_mb__after_atomic_inc(); /* might optimize out... */
}
- } else {
- WARN_ON_ONCE(current->rcu_read_lock_nesting > NR_CPUS);
- }
+ } else
+ rcu_read_lock_check_upper_limit();
+
local_irq_restore(oldirq);
}
-
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