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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: Peter 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Peter Zijlstra 2017-03-23 15:56:10 +01:00 committed by Thomas Gleixner
parent 85e2d4f992
commit aa2bfe5536
3 changed files with 18 additions and 19 deletions
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7
kernel/futex.c
View File

@ -1394,7 +1394,7 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_
{ {
u32 uninitialized_var(curval), newval; u32 uninitialized_var(curval), newval;
struct task_struct *new_owner; struct task_struct *new_owner;
bool deboost = false; bool postunlock = false;
DEFINE_WAKE_Q(wake_q); DEFINE_WAKE_Q(wake_q);
int ret = 0; 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. * 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: out_unlock:
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); 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; return ret;
} }

28
kernel/locking/rtmutex.c
View File

@ -1330,7 +1330,8 @@ static inline int rt_mutex_slowtrylock(struct rt_mutex *lock)
/* /*
* Slow path to release a rt-mutex. * 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, static bool __sched rt_mutex_slowunlock(struct rt_mutex *lock,
struct wake_q_head *wake_q) 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); raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
/* check PI boosting */ return true; /* call rt_mutex_postunlock() */
return true;
} }
/* /*
@ -1449,15 +1449,14 @@ 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); wake_up_q(wake_q);
/* Pairs with preempt_disable() in rt_mutex_slowunlock() */ /* Pairs with preempt_disable() in rt_mutex_slowunlock() */
if (deboost) preempt_enable();
preempt_enable();
} }
static inline void static inline void
@ -1466,14 +1465,12 @@ rt_mutex_fastunlock(struct rt_mutex *lock,
struct wake_q_head *wqh)) struct wake_q_head *wqh))
{ {
DEFINE_WAKE_Q(wake_q); DEFINE_WAKE_Q(wake_q);
bool deboost;
if (likely(rt_mutex_cmpxchg_release(lock, current, NULL))) if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
return; return;
deboost = slowfn(lock, &wake_q); if (slowfn(lock, &wake_q))
rt_mutex_postunlock(&wake_q);
rt_mutex_postunlock(&wake_q, deboost);
} }
/** /**
@ -1593,19 +1590,20 @@ bool __sched __rt_mutex_futex_unlock(struct rt_mutex *lock,
*/ */
preempt_disable(); preempt_disable();
return true; /* deboost and wakeups */ return true; /* call postunlock() */
} }
void __sched rt_mutex_futex_unlock(struct rt_mutex *lock) void __sched rt_mutex_futex_unlock(struct rt_mutex *lock)
{ {
DEFINE_WAKE_Q(wake_q); DEFINE_WAKE_Q(wake_q);
bool deboost; bool postunlock;
raw_spin_lock_irq(&lock->wait_lock); 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); raw_spin_unlock_irq(&lock->wait_lock);
rt_mutex_postunlock(&wake_q, deboost); if (postunlock)
rt_mutex_postunlock(&wake_q);
} }
/** /**

2
kernel/locking/rtmutex_common.h
View File

@ -122,7 +122,7 @@ extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock, extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
struct wake_q_head *wqh); 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 #ifdef CONFIG_DEBUG_RT_MUTEXES
# include "rtmutex-debug.h" # include "rtmutex-debug.h"