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locking/rtmutex: Extend the rtmutex core to support ww_mutex
Add a ww acquire context pointer to the waiter and various functions and add the ww_mutex related invocations to the proper spots in the locking code, similar to the mutex based variant. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20210815211304.966139174@linutronix.de
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@ -17,9 +17,44 @@
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#include <linux/sched/signal.h>
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#include <linux/sched/rt.h>
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#include <linux/sched/wake_q.h>
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#include <linux/ww_mutex.h>
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#include "rtmutex_common.h"
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#ifndef WW_RT
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# define build_ww_mutex() (false)
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# define ww_container_of(rtm) NULL
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static inline int __ww_mutex_add_waiter(struct rt_mutex_waiter *waiter,
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struct rt_mutex *lock,
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struct ww_acquire_ctx *ww_ctx)
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{
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return 0;
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}
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static inline void __ww_mutex_check_waiters(struct rt_mutex *lock,
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struct ww_acquire_ctx *ww_ctx)
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{
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}
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static inline void ww_mutex_lock_acquired(struct ww_mutex *lock,
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struct ww_acquire_ctx *ww_ctx)
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{
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}
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static inline int __ww_mutex_check_kill(struct rt_mutex *lock,
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struct rt_mutex_waiter *waiter,
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struct ww_acquire_ctx *ww_ctx)
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{
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return 0;
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}
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#else
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# define build_ww_mutex() (true)
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# define ww_container_of(rtm) container_of(rtm, struct ww_mutex, base)
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# include "ww_mutex.h"
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#endif
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/*
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* lock->owner state tracking:
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*
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@ -308,7 +343,28 @@ static __always_inline int rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
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static __always_inline bool __waiter_less(struct rb_node *a, const struct rb_node *b)
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{
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return rt_mutex_waiter_less(__node_2_waiter(a), __node_2_waiter(b));
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struct rt_mutex_waiter *aw = __node_2_waiter(a);
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struct rt_mutex_waiter *bw = __node_2_waiter(b);
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if (rt_mutex_waiter_less(aw, bw))
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return 1;
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if (!build_ww_mutex())
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return 0;
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if (rt_mutex_waiter_less(bw, aw))
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return 0;
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/* NOTE: relies on waiter->ww_ctx being set before insertion */
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if (aw->ww_ctx) {
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if (!bw->ww_ctx)
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return 1;
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return (signed long)(aw->ww_ctx->stamp -
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bw->ww_ctx->stamp) < 0;
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}
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return 0;
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}
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static __always_inline void
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@ -961,6 +1017,7 @@ takeit:
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static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock,
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struct rt_mutex_waiter *waiter,
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struct task_struct *task,
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struct ww_acquire_ctx *ww_ctx,
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enum rtmutex_chainwalk chwalk)
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{
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struct task_struct *owner = rt_mutex_owner(lock);
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@ -996,6 +1053,16 @@ static int __sched task_blocks_on_rt_mutex(struct rt_mutex_base *lock,
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raw_spin_unlock(&task->pi_lock);
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if (build_ww_mutex() && ww_ctx) {
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struct rt_mutex *rtm;
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/* Check whether the waiter should back out immediately */
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rtm = container_of(lock, struct rt_mutex, rtmutex);
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res = __ww_mutex_add_waiter(waiter, rtm, ww_ctx);
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if (res)
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return res;
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}
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if (!owner)
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return 0;
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@ -1281,6 +1348,7 @@ static void __sched remove_waiter(struct rt_mutex_base *lock,
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/**
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* rt_mutex_slowlock_block() - Perform the wait-wake-try-to-take loop
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* @lock: the rt_mutex to take
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* @ww_ctx: WW mutex context pointer
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* @state: the state the task should block in (TASK_INTERRUPTIBLE
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* or TASK_UNINTERRUPTIBLE)
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* @timeout: the pre-initialized and started timer, or NULL for none
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@ -1289,10 +1357,12 @@ static void __sched remove_waiter(struct rt_mutex_base *lock,
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* Must be called with lock->wait_lock held and interrupts disabled
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*/
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static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
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struct ww_acquire_ctx *ww_ctx,
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unsigned int state,
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struct hrtimer_sleeper *timeout,
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struct rt_mutex_waiter *waiter)
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{
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struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex);
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int ret = 0;
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for (;;) {
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@ -1309,6 +1379,12 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
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break;
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}
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if (build_ww_mutex() && ww_ctx) {
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ret = __ww_mutex_check_kill(rtm, waiter, ww_ctx);
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if (ret)
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break;
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}
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raw_spin_unlock_irq(&lock->wait_lock);
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schedule();
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@ -1331,6 +1407,9 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
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if (res != -EDEADLOCK || detect_deadlock)
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return;
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if (build_ww_mutex() && w->ww_ctx)
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return;
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/*
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* Yell loudly and stop the task right here.
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*/
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@ -1344,31 +1423,46 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
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/**
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* __rt_mutex_slowlock - Locking slowpath invoked with lock::wait_lock held
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* @lock: The rtmutex to block lock
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* @ww_ctx: WW mutex context pointer
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* @state: The task state for sleeping
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* @chwalk: Indicator whether full or partial chainwalk is requested
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* @waiter: Initializer waiter for blocking
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*/
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static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
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struct ww_acquire_ctx *ww_ctx,
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unsigned int state,
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enum rtmutex_chainwalk chwalk,
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struct rt_mutex_waiter *waiter)
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{
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struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex);
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struct ww_mutex *ww = ww_container_of(rtm);
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int ret;
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lockdep_assert_held(&lock->wait_lock);
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/* Try to acquire the lock again: */
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if (try_to_take_rt_mutex(lock, current, NULL))
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if (try_to_take_rt_mutex(lock, current, NULL)) {
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if (build_ww_mutex() && ww_ctx) {
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__ww_mutex_check_waiters(rtm, ww_ctx);
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ww_mutex_lock_acquired(ww, ww_ctx);
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}
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return 0;
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}
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set_current_state(state);
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ret = task_blocks_on_rt_mutex(lock, waiter, current, chwalk);
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ret = task_blocks_on_rt_mutex(lock, waiter, current, ww_ctx, chwalk);
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if (likely(!ret))
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ret = rt_mutex_slowlock_block(lock, state, NULL, waiter);
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ret = rt_mutex_slowlock_block(lock, ww_ctx, state, NULL, waiter);
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if (unlikely(ret)) {
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if (likely(!ret)) {
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/* acquired the lock */
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if (build_ww_mutex() && ww_ctx) {
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if (!ww_ctx->is_wait_die)
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__ww_mutex_check_waiters(rtm, ww_ctx);
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ww_mutex_lock_acquired(ww, ww_ctx);
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}
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} else {
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__set_current_state(TASK_RUNNING);
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remove_waiter(lock, waiter);
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rt_mutex_handle_deadlock(ret, chwalk, waiter);
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@ -1383,14 +1477,17 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
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}
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static inline int __rt_mutex_slowlock_locked(struct rt_mutex_base *lock,
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struct ww_acquire_ctx *ww_ctx,
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unsigned int state)
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{
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struct rt_mutex_waiter waiter;
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int ret;
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rt_mutex_init_waiter(&waiter);
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waiter.ww_ctx = ww_ctx;
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ret = __rt_mutex_slowlock(lock, state, RT_MUTEX_MIN_CHAINWALK, &waiter);
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ret = __rt_mutex_slowlock(lock, ww_ctx, state, RT_MUTEX_MIN_CHAINWALK,
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&waiter);
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debug_rt_mutex_free_waiter(&waiter);
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return ret;
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@ -1399,9 +1496,11 @@ static inline int __rt_mutex_slowlock_locked(struct rt_mutex_base *lock,
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/*
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* rt_mutex_slowlock - Locking slowpath invoked when fast path fails
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* @lock: The rtmutex to block lock
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* @ww_ctx: WW mutex context pointer
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* @state: The task state for sleeping
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*/
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static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
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struct ww_acquire_ctx *ww_ctx,
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unsigned int state)
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{
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unsigned long flags;
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@ -1416,7 +1515,7 @@ static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
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* irqsave/restore variants.
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*/
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raw_spin_lock_irqsave(&lock->wait_lock, flags);
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ret = __rt_mutex_slowlock_locked(lock, state);
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ret = __rt_mutex_slowlock_locked(lock, ww_ctx, state);
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raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
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return ret;
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@ -1428,7 +1527,7 @@ static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock,
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if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
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return 0;
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return rt_mutex_slowlock(lock, state);
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return rt_mutex_slowlock(lock, NULL, state);
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}
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#endif /* RT_MUTEX_BUILD_MUTEX */
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@ -1455,7 +1554,7 @@ static void __sched rtlock_slowlock_locked(struct rt_mutex_base *lock)
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/* Save current state and set state to TASK_RTLOCK_WAIT */
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current_save_and_set_rtlock_wait_state();
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task_blocks_on_rt_mutex(lock, &waiter, current, RT_MUTEX_MIN_CHAINWALK);
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task_blocks_on_rt_mutex(lock, &waiter, current, NULL, RT_MUTEX_MIN_CHAINWALK);
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for (;;) {
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/* Try to acquire the lock again */
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@ -267,7 +267,7 @@ int __sched __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock,
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return 1;
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/* We enforce deadlock detection for futexes */
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ret = task_blocks_on_rt_mutex(lock, waiter, task,
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ret = task_blocks_on_rt_mutex(lock, waiter, task, NULL,
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RT_MUTEX_FULL_CHAINWALK);
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if (ret && !rt_mutex_owner(lock)) {
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@ -343,7 +343,7 @@ int __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock,
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raw_spin_lock_irq(&lock->wait_lock);
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/* sleep on the mutex */
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set_current_state(TASK_INTERRUPTIBLE);
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ret = rt_mutex_slowlock_block(lock, TASK_INTERRUPTIBLE, to, waiter);
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ret = rt_mutex_slowlock_block(lock, NULL, TASK_INTERRUPTIBLE, to, waiter);
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/*
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* try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
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* have to fix that up.
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* @wake_state: Wakeup state to use (TASK_NORMAL or TASK_RTLOCK_WAIT)
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* @prio: Priority of the waiter
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* @deadline: Deadline of the waiter if applicable
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* @ww_ctx: WW context pointer
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*/
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struct rt_mutex_waiter {
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struct rb_node tree_entry;
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@ -37,6 +38,7 @@ struct rt_mutex_waiter {
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unsigned int wake_state;
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int prio;
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u64 deadline;
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struct ww_acquire_ctx *ww_ctx;
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};
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/**
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@ -1360,7 +1360,7 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
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__rt_mutex_lock(rtm, state)
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#define rwbase_rtmutex_slowlock_locked(rtm, state) \
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__rt_mutex_slowlock_locked(rtm, state)
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__rt_mutex_slowlock_locked(rtm, NULL, state)
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#define rwbase_rtmutex_unlock(rtm) \
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__rt_mutex_unlock(rtm)
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