[RFC 4/4] locking/spinlock: additional lock information when dumping locks

Sasha Levin
2015-01-12T14:58:33Z

Show the owner cpu and task of the lock when dumping held locks in the system.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
include/linux/lockdep.h | 2 +-
include/linux/spinlock.h | 4 ++++
include/linux/spinlock_types.h | 2 +-
kernel/locking/lockdep.c | 5 +++++
kernel/locking/spinlock_debug.c | 17 ++++++++++++++++-
5 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 4527f99..01e0b14 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -143,7 +143,7 @@ struct lock_class_stats lock_stats(struct lock_class *class);
void clear_lock_stats(struct lock_class *class);
#endif

-enum LOCK_TYPE { LOCKTYPE_NONE, LOCKTYPE_MUTEX, LOCKTYPE_RWSEM, };
+enum LOCK_TYPE { LOCKTYPE_NONE, LOCKTYPE_MUTEX, LOCKTYPE_RWSEM, LOCKTYPE_SPINLOCK, };

/*
* Map the lock object (the lock instance) to the lock-class object.
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index 3e18379..963f7626 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -409,6 +409,10 @@ static inline int spin_can_lock(spinlock_t *lock)

#define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock)

+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern void spinlock_print_debug(const spinlock_t *lock);
+#endif
+
/*
* Pull the atomic_t declaration:
* (asm-mips/atomic.h needs above definitions)
diff --git a/include/linux/spinlock_types.h b/include/linux/spinlock_types.h
index 73548eb..efbe667 100644
--- a/include/linux/spinlock_types.h
+++ b/include/linux/spinlock_types.h
@@ -36,7 +36,7 @@ typedef struct raw_spinlock {
#define SPINLOCK_OWNER_INIT ((void *)-1L)

#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define SPIN_DEP_MAP_INIT(lockname) .dep_map = { .name = #lockname }
+# define SPIN_DEP_MAP_INIT(lockname) .dep_map = { .name = #lockname, .type = LOCKTYPE_SPINLOCK }
#else
# define SPIN_DEP_MAP_INIT(lockname)
#endif
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index e75f83b..b3d4151 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -512,6 +512,7 @@ static void get_lock_info(enum LOCK_TYPE t, struct lockdep_map *map)
{
struct mutex *mtx;
struct rw_semaphore *rw;
+ spinlock_t *spin;

switch (t) {
case LOCKTYPE_NONE: break;
@@ -523,6 +524,10 @@ static void get_lock_info(enum LOCK_TYPE t, struct lockdep_map *map)
rw = container_of(map, struct rw_semaphore, dep_map);
rwsem_print_debug(rw);
break;
+ case LOCKTYPE_SPINLOCK:
+ spin = container_of(map, struct spinlock, dep_map);
+ spinlock_print_debug(spin);
+ break;
}
}

diff --git a/kernel/locking/spinlock_debug.c b/kernel/locking/spinlock_debug.c
index 0374a59..52798c0 100644
--- a/kernel/locking/spinlock_debug.c
+++ b/kernel/locking/spinlock_debug.c
@@ -21,7 +21,7 @@ void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
* Make sure we are not reinitializing a held lock:
*/
debug_check_no_locks_freed((void *)lock, sizeof(*lock));
- lockdep_init_map(&lock->dep_map, name, key, 0);
+ lockdep_init_map_type(&lock->dep_map, name, key, 0, LOCKTYPE_SPINLOCK);
#endif
lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
lock->magic = SPINLOCK_MAGIC;
@@ -300,3 +300,18 @@ void do_raw_write_unlock(rwlock_t *lock)
debug_write_unlock(lock);
arch_write_unlock(&lock->raw_lock);
}
+
+void spinlock_print_debug(const spinlock_t *lock)
+{
+ const char *owner_comm = NULL;
+ const struct task_struct *owner;
+ unsigned int cpu = lock->rlock.owner_cpu;
+
+ owner = lock->rlock.owner;
+
+ if (owner && owner != SPINLOCK_OWNER_INIT)
+ owner_comm = owner->comm;
+
+ printk("Spinlock: owner cpu: %u owner: %s\n", cpu, owner_comm);
+}
+EXPORT_SYMBOL_GPL(spinlock_print_debug);
--
1.7.10.4