Commit b576e640 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

locking/rtmutex: Provide rt_wake_q_head and helpers 



To handle the difference between wakeups for regular sleeping locks (mutex,
rtmutex, rw_semaphore) and the wakeups for 'sleeping' spin/rwlocks on
PREEMPT_RT enabled kernels correctly, it is required to provide a
wake_q_head construct which allows to keep them separate.

Provide a wrapper around wake_q_head and the required helpers, which will be
extended with the state handling later.

No functional change.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211303.139337655@linutronix.de
parent c014ef69

kernel/locking/rtmutex.c

+15 −0
Original line number Diff line number Diff line
@@ -347,6 +347,21 @@ static __always_inline void rt_mutex_adjust_prio(struct task_struct *p) 
	rt_mutex_setprio(p, pi_task);

}



/* RT mutex specific wake_q wrappers */

static __always_inline void rt_mutex_wake_q_add(struct rt_wake_q_head *wqh,

						struct rt_mutex_waiter *w)

{

	wake_q_add(&wqh->head, w->task);

}



static __always_inline void rt_mutex_wake_up_q(struct rt_wake_q_head *wqh)

{

	wake_up_q(&wqh->head);



	/* Pairs with preempt_disable() in mark_wakeup_next_waiter() */

	preempt_enable();

}



/*

 * Deadlock detection is conditional:

 *

kernel/locking/rtmutex_common.h

+14 −0
Original line number Diff line number Diff line
@@ -39,6 +39,20 @@ struct rt_mutex_waiter { 
	u64			deadline;

};



/**

 * rt_wake_q_head - Wrapper around regular wake_q_head to support

 *		    "sleeping" spinlocks on RT

 * @head:	The regular wake_q_head for sleeping lock variants

 */

struct rt_wake_q_head {

	struct wake_q_head	head;

};



#define DEFINE_RT_WAKE_Q(name)						\

	struct rt_wake_q_head name = {					\

		.head		= WAKE_Q_HEAD_INITIALIZER(name.head),	\

	}



/*

 * PI-futex support (proxy locking functions, etc.):

 */