On Sat, Jun 10, 2017 at 02:48:04AM +0000, Levin, Alexander (Sasha Levin) wrote:
> lockdep can't deal with NULL name or key, and doesn't do anything
> with the lock when that happens.
Not doing anything is 'right', the proxy stuff won't be lockdep tracked
anyway. But yeah, the first thing is a wee bit of a problem, for it will
trigger DEBUG_LOCKS_WARN_ON() and fully kill lockdep.
> Make rt_mutex_init_proxy_locked pass a name and a key for the lock.
>
> Fixes: f5694788ad8d ("rt_mutex: Add lockdep annotations")
> Cc: Linus Torvalds <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: [email protected]
> Signed-off-by: Sasha Levin <[email protected]>
> ---
> kernel/locking/rtmutex.c | 6 ++++--
> kernel/locking/rtmutex_common.h | 12 ++++++++++--
> 2 files changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> index 43123533e9b1..f540961cec30 100644
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
> @@ -1679,10 +1679,12 @@ EXPORT_SYMBOL_GPL(__rt_mutex_init);
> * possible at this point because the pi_state which contains the rtmutex
> * is not yet visible to other tasks.
> */
> -void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
> +void __rt_mutex_init_proxy_locked(struct rt_mutex *lock,
> + const char *name,
> + struct lock_class_key *key,
> struct task_struct *proxy_owner)
> {
> - __rt_mutex_init(lock, NULL, NULL);
> + __rt_mutex_init(lock, name, key);
> debug_rt_mutex_proxy_lock(lock, proxy_owner);
> rt_mutex_set_owner(lock, proxy_owner);
> }
Yeah, no need to do that; all we really need here is something like:
---
kernel/locking/rtmutex-debug.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c
index ac35e648b0e5..8dc647dc4b4b 100644
--- a/kernel/locking/rtmutex-debug.c
+++ b/kernel/locking/rtmutex-debug.c
@@ -175,7 +175,8 @@ void debug_rt_mutex_init(struct rt_mutex *lock, const char
*name, struct lock_cl
lock->name = name;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
- lockdep_init_map(&lock->dep_map, name, key, 0);
+ if (name && key)
+ lockdep_init_map(&lock->dep_map, name, key, 0);
#endif
}
