Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 2/3] rcu: add debug check for too many rcu_read_unlock() | Date | Mon, 4 Jan 2010 16:04:01 -0800 |
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From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
TREE_PREEMPT_RCU maintains an rcu_read_lock_nesting counter in the task structure, which happens to be a signed int. So this patch adds a check for this counter being negative at the end of __rcu_read_unlock(). This check is under CONFIG_PROVE_LOCKING, so can be thought of as being part of lockdep.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- kernel/rcutree_plugin.h | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index f11ebd4..e77cdf3 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -304,6 +304,9 @@ void __rcu_read_unlock(void) if (--ACCESS_ONCE(t->rcu_read_lock_nesting) == 0 && unlikely(ACCESS_ONCE(t->rcu_read_unlock_special))) rcu_read_unlock_special(t); +#ifdef CONFIG_PROVE_LOCKING + WARN_ON_ONCE(ACCESS_ONCE(t->rcu_read_lock_nesting) < 0); +#endif /* #ifdef CONFIG_PROVE_LOCKING */ } EXPORT_SYMBOL_GPL(__rcu_read_unlock); -- 1.5.2.5
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