From: Sebastian Andrzej Siewior Date: Thu, 16 Nov 2017 16:48:48 +0100 Subject: [PATCH] locking/rtmutex: re-init the wait_lock in rt_mutex_init_proxy_locked() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.1-rt3.tar.xz We could provide a key-class for the lockdep (and fixup all callers) or move the init to all callers (like it was) in order to avoid lockdep seeing a double-lock of the wait_lock. Reported-by: Fernando Lopez-Lezcano Signed-off-by: Sebastian Andrzej Siewior --- kernel/locking/rtmutex.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -2281,6 +2281,14 @@ void rt_mutex_init_proxy_locked(struct r struct task_struct *proxy_owner) { __rt_mutex_init(lock, NULL, NULL); +#ifdef CONFIG_DEBUG_SPINLOCK + /* + * get another key class for the wait_lock. LOCK_PI and UNLOCK_PI is + * holding the ->wait_lock of the proxy_lock while unlocking a sleeping + * lock. + */ + raw_spin_lock_init(&lock->wait_lock); +#endif debug_rt_mutex_proxy_lock(lock, proxy_owner); rt_mutex_set_owner(lock, proxy_owner); }