locking: Add Sony's mutex_trylock_spin (849a4067) · Commits · e / devices / android_kernel_sony_msm8998

include/linux/mutex.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -7,6 +7,11 @@
		*
		* This file contains the main data structure and API definitions.
		*/
		/*
		* NOTE: This file has been modified by Sony Mobile Communications Inc.
		* Modifications are Copyright (c) 2017 Sony Mobile Communications Inc,
		* and licensed under the license of the file.
		*/
		#ifndef __LINUX_MUTEX_H
		#define __LINUX_MUTEX_H

		@@ -171,6 +176,7 @@ extern int __must_check mutex_lock_killable(struct mutex *lock);
		* Returns 1 if the mutex has been acquired successfully, and 0 on contention.
		*/
		extern int mutex_trylock(struct mutex *lock);
		extern int mutex_trylock_spin(struct mutex *lock);
		extern void mutex_unlock(struct mutex *lock);

		extern int atomic_dec_and_mutex_lock(atomic_t cnt, struct mutex lock);

kernel/locking/mutex.c

+26 −12

Original line number	Diff line number	Diff line
		@@ -17,6 +17,11 @@
		*
		* Also see Documentation/locking/mutex-design.txt.
		*/
		/*
		* NOTE: This file has been modified by Sony Mobile Communications Inc.
		* Modifications are Copyright (c) 2017 Sony Mobile Communications Inc,
		* and licensed under the license of the file.
		*/
		#include <linux/mutex.h>
		#include <linux/ww_mutex.h>
		#include <linux/sched.h>
		@@ -26,7 +31,6 @@
		#include <linux/interrupt.h>
		#include <linux/debug_locks.h>
		#include <linux/osq_lock.h>
		#include <linux/delay.h>

		/*
		* In the DEBUG case we are using the "NULL fastpath" for mutexes,
		@@ -379,17 +383,6 @@ static bool mutex_optimistic_spin(struct mutex *lock,
		* values at the cost of a few extra spins.
		*/
		cpu_relax_lowlatency();

		/*
		* On arm systems, we must slow down the waiter's repeated
		* aquisition of spin_mlock and atomics on the lock count, or
		* we risk starving out a thread attempting to release the
		* mutex. The mutex slowpath release must take spin lock
		* wait_lock. This spin lock can share a monitor with the
		* other waiter atomics in the mutex data structure, so must
		* take care to rate limit the waiters.
		*/
		udelay(1);
		}

		osq_unlock(&lock->osq);
		@@ -925,6 +918,27 @@ int __sched mutex_trylock(struct mutex *lock)
		}
		EXPORT_SYMBOL(mutex_trylock);

		int __sched mutex_trylock_spin(struct mutex *lock)
		{
		int ret;

		ret = __mutex_fastpath_trylock(&lock->count,
		__mutex_trylock_slowpath);

		if (!ret) {
		preempt_disable();
		ret = mutex_optimistic_spin(lock, NULL, 0);
		if (ret)
		mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
		preempt_enable();
		}
		if (ret)
		mutex_set_owner(lock);

		return ret;
		}
		EXPORT_SYMBOL(mutex_trylock_spin);

		#ifndef CONFIG_DEBUG_LOCK_ALLOC
		int __sched
		__ww_mutex_lock(struct ww_mutex lock, struct ww_acquire_ctx ctx)