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Code Issues Releases Wiki Activity

locking/rtmutex: Provide rt_mutex_slowlock_locked()

Browse source 
Split the inner workings of rt_mutex_slowlock() out into a separate
function, which can be reused by the upcoming RT lock substitutions,
e.g. for rw_semaphores.

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/20210815211302.841971086@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-08-15 23:28:00 +02:00 committed by Ingo Molnar
parent 830e6acc8a
commit ebbdc41e90
2 changed files with 68 additions and 52 deletions
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118
kernel/locking/rtmutex.c
View file

@ -1106,7 +1106,7 @@ static void __sched remove_waiter(struct rt_mutex_base *lock,
}
/**
* __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
* rt_mutex_slowlock_block() - Perform the wait-wake-try-to-take loop
* @lock: the rt_mutex to take
* @state: the state the task should block in (TASK_INTERRUPTIBLE
* or TASK_UNINTERRUPTIBLE)
@ -1115,10 +1115,10 @@ static void __sched remove_waiter(struct rt_mutex_base *lock,
*
* Must be called with lock->wait_lock held and interrupts disabled
*/
static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
unsigned int state,
struct hrtimer_sleeper *timeout,
struct rt_mutex_waiter *waiter)
static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
unsigned int state,
struct hrtimer_sleeper *timeout,
struct rt_mutex_waiter *waiter)
{
int ret = 0;
@ -1168,20 +1168,72 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
}
}
/*
* Slow path lock function:
/**
* __rt_mutex_slowlock - Locking slowpath invoked with lock::wait_lock held
* @lock: The rtmutex to block lock
* @state: The task state for sleeping
* @chwalk: Indicator whether full or partial chainwalk is requested
* @waiter: Initializer waiter for blocking
*/
static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
unsigned int state,
struct hrtimer_sleeper *timeout,
enum rtmutex_chainwalk chwalk)
static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
unsigned int state,
enum rtmutex_chainwalk chwalk,
struct rt_mutex_waiter *waiter)
{
int ret;
lockdep_assert_held(&lock->wait_lock);
/* Try to acquire the lock again: */
if (try_to_take_rt_mutex(lock, current, NULL))
return 0;
set_current_state(state);
ret = task_blocks_on_rt_mutex(lock, waiter, current, chwalk);
if (likely(!ret))
ret = rt_mutex_slowlock_block(lock, state, NULL, waiter);
if (unlikely(ret)) {
__set_current_state(TASK_RUNNING);
remove_waiter(lock, waiter);
rt_mutex_handle_deadlock(ret, chwalk, waiter);
}
/*
* try_to_take_rt_mutex() sets the waiter bit
* unconditionally. We might have to fix that up.
*/
fixup_rt_mutex_waiters(lock);
return ret;
}
static inline int __rt_mutex_slowlock_locked(struct rt_mutex_base *lock,
unsigned int state)
{
struct rt_mutex_waiter waiter;
unsigned long flags;
int ret = 0;
int ret;
rt_mutex_init_waiter(&waiter);
ret = __rt_mutex_slowlock(lock, state, RT_MUTEX_MIN_CHAINWALK, &waiter);
debug_rt_mutex_free_waiter(&waiter);
return ret;
}
/*
* rt_mutex_slowlock - Locking slowpath invoked when fast path fails
* @lock: The rtmutex to block lock
* @state: The task state for sleeping
*/
static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
unsigned int state)
{
unsigned long flags;
int ret;
/*
* Technically we could use raw_spin_[un]lock_irq() here, but this can
* be called in early boot if the cmpxchg() fast path is disabled
@ -1191,45 +1243,9 @@ static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
* irqsave/restore variants.
*/
raw_spin_lock_irqsave(&lock->wait_lock, flags);
/* Try to acquire the lock again: */
if (try_to_take_rt_mutex(lock, current, NULL)) {
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
return 0;
}
set_current_state(state);
/* Setup the timer, when timeout != NULL */
if (unlikely(timeout))
hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS);
ret = task_blocks_on_rt_mutex(lock, &waiter, current, chwalk);
if (likely(!ret))
/* sleep on the mutex */
ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
if (unlikely(ret)) {
__set_current_state(TASK_RUNNING);
remove_waiter(lock, &waiter);
rt_mutex_handle_deadlock(ret, chwalk, &waiter);
}
/*
* try_to_take_rt_mutex() sets the waiter bit
* unconditionally. We might have to fix that up.
*/
fixup_rt_mutex_waiters(lock);
ret = __rt_mutex_slowlock_locked(lock, state);
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
/* Remove pending timer: */
if (unlikely(timeout))
hrtimer_cancel(&timeout->timer);
debug_rt_mutex_free_waiter(&waiter);
return ret;
}
@ -1239,7 +1255,7 @@ static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock,
if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 0;
return rt_mutex_slowlock(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
return rt_mutex_slowlock(lock, state);
}
static int __sched __rt_mutex_slowtrylock(struct rt_mutex_base *lock)

2
kernel/locking/rtmutex_api.c
View file

@ -342,7 +342,7 @@ int __sched rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock,
raw_spin_lock_irq(&lock->wait_lock);
/* sleep on the mutex */
set_current_state(TASK_INTERRUPTIBLE);
ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
ret = rt_mutex_slowlock_block(lock, TASK_INTERRUPTIBLE, to, waiter);
/*
* try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
* have to fix that up.