From: Ingo Molnar Add proxy-locking rt-mutex functionality needed by pi-futexes. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Signed-off-by: Arjan van de Ven Signed-off-by: Andrew Morton --- include/linux/rtmutex_internal.h | 8 ++++ kernel/rtmutex.c | 55 +++++++++++++++++++++++++++++ 2 files changed, 63 insertions(+) diff -puN include/linux/rtmutex_internal.h~pi-futex-rt-mutex-futex-api include/linux/rtmutex_internal.h --- devel/include/linux/rtmutex_internal.h~pi-futex-rt-mutex-futex-api 2006-03-25 19:05:11.000000000 -0800 +++ devel-akpm/include/linux/rtmutex_internal.h 2006-03-25 19:05:11.000000000 -0800 @@ -176,4 +176,12 @@ static inline void mark_rt_mutex_waiters #endif +/* + * PI-futex support (proxy locking functions, etc.): + */ +extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock); +extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock, + struct task_struct *proxy_owner); +extern void rt_mutex_proxy_unlock(struct rt_mutex *lock, + struct task_struct *proxy_owner); #endif diff -puN kernel/rtmutex.c~pi-futex-rt-mutex-futex-api kernel/rtmutex.c --- devel/kernel/rtmutex.c~pi-futex-rt-mutex-futex-api 2006-03-25 19:05:11.000000000 -0800 +++ devel-akpm/kernel/rtmutex.c 2006-03-25 19:05:11.000000000 -0800 @@ -940,3 +940,58 @@ void fastcall __rt_mutex_init(struct rt_ debug_rt_mutex_init(lock, name); } EXPORT_SYMBOL_GPL(__rt_mutex_init); + +/** + * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a + * proxy owner + * + * @lock: the rt_mutex to be locked + * @proxy_owner:the task to set as owner + * + * No locking. Caller has to do serializing itself + * Special API call for PI-futex support + */ +void rt_mutex_init_proxy_locked(struct rt_mutex *lock, + struct task_struct *proxy_owner) +{ + __rt_mutex_init(lock, NULL); + debug_rt_mutex_lock(lock __RET_IP__); + rt_mutex_set_owner(lock, proxy_owner, 0); + rt_mutex_deadlock_account_lock(lock, proxy_owner); +} + +/** + * rt_mutex_proxy_unlock - release a lock on behalf of owner + * + * @lock: the rt_mutex to be locked + * + * No locking. Caller has to do serializing itself + * Special API call for PI-futex support + */ +void rt_mutex_proxy_unlock(struct rt_mutex *lock, + struct task_struct *proxy_owner) +{ + debug_rt_mutex_proxy_unlock(lock); + rt_mutex_set_owner(lock, NULL, 0); + rt_mutex_deadlock_account_unlock(proxy_owner); +} + +/** + * rt_mutex_next_owner - return the next owner of the lock + * + * @lock: the rt lock query + * + * Returns the next owner of the lock or NULL + * + * Caller has to serialize against other accessors to the lock + * itself. + * + * Special API call for PI-futex support + */ +struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock) +{ + if (!rt_mutex_has_waiters(lock)) + return NULL; + + return rt_mutex_top_waiter(lock)->task; +} _