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Commit aa2bfe55 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Thomas Gleixner
Browse files

rtmutex: Clean up 



Previous patches changed the meaning of the return value of
rt_mutex_slowunlock(); update comments and code to reflect this.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: xlpang@redhat.com
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170323150216.255058238@infradead.org


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 85e2d4f9

kernel/futex.c

+4 −3
Original line number Diff line number Diff line
@@ -1394,7 +1394,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_ 
{

	u32 uninitialized_var(curval), newval;

	struct task_struct *new_owner;

	bool deboost = false;

	bool postunlock = false;

	DEFINE_WAKE_Q(wake_q);

	int ret = 0;
@@ -1455,12 +1455,13 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_ 
	/*

	 * We've updated the uservalue, this unlock cannot fail.

	 */

	deboost = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);

	postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q);



out_unlock:

	raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);



	rt_mutex_postunlock(&wake_q, deboost);

	if (postunlock)

		rt_mutex_postunlock(&wake_q);



	return ret;

}

kernel/locking/rtmutex.c

+13 −15
Original line number Diff line number Diff line
@@ -1330,7 +1330,8 @@ static inline int rt_mutex_slowtrylock(struct rt_mutex *lock) 


/*

 * Slow path to release a rt-mutex.

 * Return whether the current task needs to undo a potential priority boosting.

 *

 * Return whether the current task needs to call rt_mutex_postunlock().

 */

static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,

					struct wake_q_head *wake_q)
@@ -1401,8 +1402,7 @@ static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock, 


	raw_spin_unlock_irqrestore(&lock->wait_lock, flags);



	/* check PI boosting */

	return true;

	return true; /* call rt_mutex_postunlock() */

}



/*
@@ -1449,14 +1449,13 @@ rt_mutex_fasttrylock(struct rt_mutex *lock, 
}



/*

 * Undo pi boosting (if necessary) and wake top waiter.

 * Performs the wakeup of the the top-waiter and re-enables preemption.

 */

void rt_mutex_postunlock(struct wake_q_head *wake_q, bool deboost)

void rt_mutex_postunlock(struct wake_q_head *wake_q)

{

	wake_up_q(wake_q);



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

	if (deboost)

	preempt_enable();

}
@@ -1466,14 +1465,12 @@ rt_mutex_fastunlock(struct rt_mutex *lock, 
				   struct wake_q_head *wqh))

{

	DEFINE_WAKE_Q(wake_q);

	bool deboost;



	if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))

		return;



	deboost = slowfn(lock, &wake_q);



	rt_mutex_postunlock(&wake_q, deboost);

	if (slowfn(lock, &wake_q))

		rt_mutex_postunlock(&wake_q);

}



/**
@@ -1593,19 +1590,20 @@ bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock, 
	 */

	preempt_disable();



	return true; /* deboost and wakeups */

	return true; /* call postunlock() */

}



void __sched rt_mutex_futex_unlock(struct rt_mutex *lock)

{

	DEFINE_WAKE_Q(wake_q);

	bool deboost;

	bool postunlock;



	raw_spin_lock_irq(&lock->wait_lock);

	deboost = __rt_mutex_futex_unlock(lock, &wake_q);

	postunlock = __rt_mutex_futex_unlock(lock, &wake_q);

	raw_spin_unlock_irq(&lock->wait_lock);



	rt_mutex_postunlock(&wake_q, deboost);

	if (postunlock)

		rt_mutex_postunlock(&wake_q);

}



/**

kernel/locking/rtmutex_common.h

+1 −1
Original line number Diff line number Diff line
@@ -122,7 +122,7 @@ extern void rt_mutex_futex_unlock(struct rt_mutex *lock); 
extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,

				 struct wake_q_head *wqh);



extern void rt_mutex_postunlock(struct wake_q_head *wake_q, bool deboost);

extern void rt_mutex_postunlock(struct wake_q_head *wake_q);



#ifdef CONFIG_DEBUG_RT_MUTEXES

# include "rtmutex-debug.h"