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authorPeter Zijlstra <peterz@infradead.org>2017-03-23 15:56:10 +0100
committerThomas Gleixner <tglx@linutronix.de>2017-04-04 11:44:05 +0200
commitaa2bfe55366552cb7e93e8709d66e698d79ccc47 (patch)
treec88ac6fbcf4a8ef48d40a1d9e40ff40ffeab0758
parent85e2d4f992868ad78dc8bb2c077b652fcfb3661a (diff)
downloadlinux-aa2bfe55366552cb7e93e8709d66e698d79ccc47.tar.bz2
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>
-rw-r--r--kernel/futex.c7
-rw-r--r--kernel/locking/rtmutex.c28
-rw-r--r--kernel/locking/rtmutex_common.h2
3 files changed, 18 insertions, 19 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 414a30dbc6b6..c3eebcdac206 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -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;
}
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 8faf472c430f..4b1015ef0dc7 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -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() */
}
/*
@@ -1449,15 +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);
/* Pairs with preempt_disable() in rt_mutex_slowunlock() */
- if (deboost)
- preempt_enable();
+ preempt_enable();
}
static inline void
@@ -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);
}
/**
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index a09c02982391..9e36aeddce18 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -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"