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Subject[PATCH] lockdep: annotate rcu_read_{,un}lock()
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There seem to be some unbalanced rcu_read_{,un}lock() issues of late,
how about doing something like this:
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/lockdep.h | 7 +++++++
include/linux/rcupdate.h | 12 ++++++++++++
kernel/rcupdate.c | 8 ++++++++
3 files changed, 27 insertions(+)
Index: linux-2.6/include/linux/lockdep.h
===================================================================
--- linux-2.6.orig/include/linux/lockdep.h
+++ linux-2.6/include/linux/lockdep.h
@@ -252,6 +252,13 @@ extern void lockdep_init_map(struct lock
struct lock_class_key *key, int subclass);

/*
+ * To initialize a lockdep_map statically use this macro.
+ * Note that _name must not be NULL.
+ */
+#define STATIC_LOCKDEP_MAP_INIT(_name, _key) \
+ { .name = (_name), .key = (void *)(_key), }
+
+/*
* Reinitialize a lock key - for cases where there is special locking or
* special initialization of locks so that the validator gets the scope
* of dependencies wrong: they are either too broad (they need a class-split)
Index: linux-2.6/include/linux/rcupdate.h
===================================================================
--- linux-2.6.orig/include/linux/rcupdate.h
+++ linux-2.6/include/linux/rcupdate.h
@@ -41,6 +41,7 @@
#include <linux/percpu.h>
#include <linux/cpumask.h>
#include <linux/seqlock.h>
+#include <linux/lockdep.h>

/**
* struct rcu_head - callback structure for use with RCU
@@ -133,6 +134,15 @@ static inline void rcu_bh_qsctr_inc(int
extern int rcu_pending(int cpu);
extern int rcu_needs_cpu(int cpu);

+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern struct lockdep_map rcu_lock_map;
+# define rcu_read_acquire() lock_acquire(&rcu_lock_map, 0, 0, 2, 1, _THIS_IP_)
+# define rcu_read_release() lock_release(&rcu_lock_map, 1, _THIS_IP_)
+#else
+# define rcu_read_acquire() do { } while (0)
+# define rcu_read_release() do { } while (0)
+#endif
+
/**
* rcu_read_lock - mark the beginning of an RCU read-side critical section.
*
@@ -166,6 +176,7 @@ extern int rcu_needs_cpu(int cpu);
do { \
preempt_disable(); \
__acquire(RCU); \
+ rcu_read_acquire(); \
} while(0)

/**
@@ -175,6 +186,7 @@ extern int rcu_needs_cpu(int cpu);
*/
#define rcu_read_unlock() \
do { \
+ rcu_read_release(); \
__release(RCU); \
preempt_enable(); \
} while(0)
Index: linux-2.6/kernel/rcupdate.c
===================================================================
--- linux-2.6.orig/kernel/rcupdate.c
+++ linux-2.6/kernel/rcupdate.c
@@ -49,6 +49,14 @@
#include <linux/cpu.h>
#include <linux/mutex.h>

+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key rcu_lock_key;
+struct lockdep_map rcu_lock_map =
+ STATIC_LOCKDEP_MAP_INIT("rcu_read_lock", &rcu_lock_key);
+
+EXPORT_SYMBOL_GPL(rcu_lock_map);
+#endif
+
/* Definition for rcupdate control block. */
static struct rcu_ctrlblk rcu_ctrlblk = {
.cur = -300,

-
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