lockdep: spin_lock_nest_lock()
Expose the new lock protection lock.
This can be used to annotate places where we take multiple locks of the
same class and avoid deadlocks by always taking another (top-level) lock
first.
NOTE: we're still bound to the MAX_LOCK_DEPTH (48) limit.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 93a8cc0..4452c04 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -410,8 +410,10 @@
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
+# define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
# else
# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
+# define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, NULL, i)
# endif
# define spin_release(l, n, i) lock_release(l, n, i)
#else
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index 61e5610..e0c0fcc 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -183,8 +183,14 @@
#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define spin_lock_nested(lock, subclass) _spin_lock_nested(lock, subclass)
+# define spin_lock_nest_lock(lock, nest_lock) \
+ do { \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
+ _spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
+ } while (0)
#else
# define spin_lock_nested(lock, subclass) _spin_lock(lock)
+# define spin_lock_nest_lock(lock, nest_lock) _spin_lock(lock)
#endif
#define write_lock(lock) _write_lock(lock)
diff --git a/include/linux/spinlock_api_smp.h b/include/linux/spinlock_api_smp.h
index 8a2307ce..d79845d 100644
--- a/include/linux/spinlock_api_smp.h
+++ b/include/linux/spinlock_api_smp.h
@@ -22,6 +22,8 @@
void __lockfunc _spin_lock(spinlock_t *lock) __acquires(lock);
void __lockfunc _spin_lock_nested(spinlock_t *lock, int subclass)
__acquires(lock);
+void __lockfunc _spin_lock_nest_lock(spinlock_t *lock, struct lockdep_map *map)
+ __acquires(lock);
void __lockfunc _read_lock(rwlock_t *lock) __acquires(lock);
void __lockfunc _write_lock(rwlock_t *lock) __acquires(lock);
void __lockfunc _spin_lock_bh(spinlock_t *lock) __acquires(lock);
diff --git a/kernel/spinlock.c b/kernel/spinlock.c
index a1fb54c..44baeea 100644
--- a/kernel/spinlock.c
+++ b/kernel/spinlock.c
@@ -292,6 +292,7 @@
}
EXPORT_SYMBOL(_spin_lock_nested);
+
unsigned long __lockfunc _spin_lock_irqsave_nested(spinlock_t *lock, int subclass)
{
unsigned long flags;
@@ -314,6 +315,16 @@
EXPORT_SYMBOL(_spin_lock_irqsave_nested);
+void __lockfunc _spin_lock_nest_lock(spinlock_t *lock,
+ struct lockdep_map *nest_lock)
+{
+ preempt_disable();
+ spin_acquire_nest(&lock->dep_map, 0, 0, nest_lock, _RET_IP_);
+ LOCK_CONTENDED(lock, _raw_spin_trylock, _raw_spin_lock);
+}
+
+EXPORT_SYMBOL(_spin_lock_nest_lock);
+
#endif
void __lockfunc _spin_unlock(spinlock_t *lock)