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Date: Mon, 12 Jan 2015 09:57:10 -0500
From: Sasha Levin <sasha.levin@...cle.com>
To: linux-kernel@...r.kernel.org
Cc: peterz@...radead.org, mingo@...hat.com,
Sasha Levin <sasha.levin@...cle.com>
Subject: [RFC 3/4] locking/rwsem: additional lock information when dumping locks
Show the counter and the owner of the lock when dumping held locks in the
system.
This is useful to figure out who really holds a lock and how many waiters
it has.
Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
include/linux/lockdep.h | 2 +-
include/linux/rwsem.h | 3 ++-
kernel/locking/lockdep.c | 5 +++++
kernel/locking/rwsem-spinlock.c | 7 ++++++-
kernel/locking/rwsem-xadd.c | 2 +-
kernel/locking/rwsem.c | 15 +++++++++++++++
6 files changed, 30 insertions(+), 4 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index cab929b..4527f99 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, };
+enum LOCK_TYPE { LOCKTYPE_NONE, LOCKTYPE_MUTEX, LOCKTYPE_RWSEM, };
/*
* Map the lock object (the lock instance) to the lock-class object.
diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
index 8f498cd..68732af 100644
--- a/include/linux/rwsem.h
+++ b/include/linux/rwsem.h
@@ -60,7 +60,8 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem)
/* Common initializer macros and functions */
#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
+extern void rwsem_print_debug(const struct rw_semaphore *sem);
+# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname, .type = LOCKTYPE_RWSEM }
#else
# define __RWSEM_DEP_MAP_INIT(lockname)
#endif
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 07c337d..e75f83b 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -511,6 +511,7 @@ void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
static void get_lock_info(enum LOCK_TYPE t, struct lockdep_map *map)
{
struct mutex *mtx;
+ struct rw_semaphore *rw;
switch (t) {
case LOCKTYPE_NONE: break;
@@ -518,6 +519,10 @@ static void get_lock_info(enum LOCK_TYPE t, struct lockdep_map *map)
mtx = container_of(map, struct mutex, dep_map);
mutex_print_debug(mtx);
break;
+ case LOCKTYPE_RWSEM:
+ rw = container_of(map, struct rw_semaphore, dep_map);
+ rwsem_print_debug(rw);
+ break;
}
}
diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c
index 2c93571..b07029e 100644
--- a/kernel/locking/rwsem-spinlock.c
+++ b/kernel/locking/rwsem-spinlock.c
@@ -44,7 +44,7 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name,
* Make sure we are not reinitializing a held semaphore:
*/
debug_check_no_locks_freed((void *)sem, sizeof(*sem));
- lockdep_init_map(&sem->dep_map, name, key, 0);
+ lockdep_init_map_type(&sem->dep_map, name, key, 0, LOCKTYPE_RWSEM);
#endif
sem->count = 0;
raw_spin_lock_init(&sem->wait_lock);
@@ -294,3 +294,8 @@ void __downgrade_write(struct rw_semaphore *sem)
raw_spin_unlock_irqrestore(&sem->wait_lock, flags);
}
+void rwsem_print_debug(const struct rw_semaphore *sem)
+{
+ printk("RWsem: count: %l\n", sem->count);
+}
+EXPORT_SYMBOL_GPL(rwsem_print_debug);
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 7628c3f..8b00656 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -77,7 +77,7 @@ void __init_rwsem(struct rw_semaphore *sem, const char *name,
* Make sure we are not reinitializing a held semaphore:
*/
debug_check_no_locks_freed((void *)sem, sizeof(*sem));
- lockdep_init_map(&sem->dep_map, name, key, 0);
+ lockdep_init_map_type(&sem->dep_map, name, key, 0, LOCKTYPE_RWSEM);
#endif
sem->count = RWSEM_UNLOCKED_VALUE;
raw_spin_lock_init(&sem->wait_lock);
diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index e2d3bc7..24183cc 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -181,6 +181,21 @@ void up_read_non_owner(struct rw_semaphore *sem)
EXPORT_SYMBOL(up_read_non_owner);
+void rwsem_print_debug(const struct rw_semaphore *sem)
+{
+ const char *owner = "Unknown";
+
+#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
+ if (sem->owner)
+ owner = sem->owner->comm;
+ else
+ owner = "None";
+#endif
+
+ printk("RWsem: count: %ld owner: %s\n", sem->count, owner);
+}
+EXPORT_SYMBOL_GPL(rwsem_print_debug);
+
#endif
--
1.7.10.4
--
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