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locking/rtmutex: Provide the spin/rwlock core lock function

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A simplified version of the rtmutex slowlock function, which neither handles
signals nor timeouts, and is careful about preserving the state of the
blocked task across the lock operation.

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/20210815211303.770228446@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-08-15 23:28:25 +02:00 committed by Ingo Molnar
parent 342a93247e
commit 1c143c4b65
2 changed files with 61 additions and 1 deletions
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60
kernel/locking/rtmutex.c
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@ -1416,3 +1416,63 @@ static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock,
return rt_mutex_slowlock(lock, state);
}
#endif /* RT_MUTEX_BUILD_MUTEX */
#ifdef RT_MUTEX_BUILD_SPINLOCKS
/*
* Functions required for spin/rw_lock substitution on RT kernels
*/
/**
* rtlock_slowlock_locked - Slow path lock acquisition for RT locks
* @lock: The underlying RT mutex
*/
static void __sched rtlock_slowlock_locked(struct rt_mutex_base *lock)
{
struct rt_mutex_waiter waiter;
lockdep_assert_held(&lock->wait_lock);
if (try_to_take_rt_mutex(lock, current, NULL))
return;
rt_mutex_init_rtlock_waiter(&waiter);
/* Save current state and set state to TASK_RTLOCK_WAIT */
current_save_and_set_rtlock_wait_state();
task_blocks_on_rt_mutex(lock, &waiter, current, RT_MUTEX_MIN_CHAINWALK);
for (;;) {
/* Try to acquire the lock again */
if (try_to_take_rt_mutex(lock, current, &waiter))
break;
raw_spin_unlock_irq(&lock->wait_lock);
schedule_rtlock();
raw_spin_lock_irq(&lock->wait_lock);
set_current_state(TASK_RTLOCK_WAIT);
}
/* Restore the task state */
current_restore_rtlock_saved_state();
/*
* try_to_take_rt_mutex() sets the waiter bit unconditionally.
* We might have to fix that up:
*/
fixup_rt_mutex_waiters(lock);
debug_rt_mutex_free_waiter(&waiter);
}
static __always_inline void __sched rtlock_slowlock(struct rt_mutex_base *lock)
{
unsigned long flags;
raw_spin_lock_irqsave(&lock->wait_lock, flags);
rtlock_slowlock_locked(lock);
raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
}
#endif /* RT_MUTEX_BUILD_SPINLOCKS */

2
kernel/locking/rtmutex_common.h
View File

@ -181,7 +181,7 @@ static inline void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
waiter->task = NULL;
}
static inline void rtlock_init_rtmutex_waiter(struct rt_mutex_waiter *waiter)
static inline void rt_mutex_init_rtlock_waiter(struct rt_mutex_waiter *waiter)
{
rt_mutex_init_waiter(waiter);
waiter->wake_state = TASK_RTLOCK_WAIT;