/* SPDX-License-Identifier: GPL-2.0 *//* * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * Authors: Waiman Long <longman@redhat.com> */ #ifndef __LOCKING_LOCK_EVENTS_H#define __LOCKING_LOCK_EVENTS_H enum lock_events { #include "lock_events_list.h" 	lockevent_num,	/* Total number of lock event counts */	LOCKEVENT_reset_cnts = lockevent_num,}; #ifdef CONFIG_LOCK_EVENT_COUNTS/* * Per-cpu counters */DECLARE_PER_CPU(unsigned long, lockevents[lockevent_num]); /* * The purpose of the lock event counting subsystem is to provide a low * overhead way to record the number of specific locking events by using * percpu counters. It is the percpu sum that matters, not specifically * how many of them happens in each cpu. * * It is possible that the same percpu counter may be modified in both * the process and interrupt contexts. For architectures that perform * percpu operation with multiple instructions, it is possible to lose * count if a process context percpu update is interrupted in the middle * and the same counter is updated in the interrupt context. Therefore, * the generated percpu sum may not be precise. The error, if any, should * be small and insignificant. * * For those architectures that do multi-instruction percpu operation, * preemption in the middle and moving the task to another cpu may cause * a larger error in the count. Again, this will be few and far between. * Given the imprecise nature of the count and the possibility of resetting * the count and doing the measurement again, this is not really a big * problem. * * To get a better picture of what is happening under the hood, it is * suggested that a few measurements should be taken with the counts * reset in between to stamp out outliner because of these possible * error conditions. * * To minimize overhead, we use __this_cpu_*() in all cases except when * CONFIG_DEBUG_PREEMPT is defined. In this particular case, this_cpu_*() * will be used to avoid the appearance of unwanted BUG messages. */#ifdef CONFIG_DEBUG_PREEMPT#define lockevent_percpu_inc(x)		this_cpu_inc(x)#define lockevent_percpu_add(x, v)	this_cpu_add(x, v)#else#define lockevent_percpu_inc(x)		__this_cpu_inc(x)#define lockevent_percpu_add(x, v)	__this_cpu_add(x, v)#endif /* * Increment the PV qspinlock statistical counters */static inline void __lockevent_inc(enum lock_events event, bool cond){	if (cond)		lockevent_percpu_inc(lockevents[event]);} #define lockevent_inc(ev)	  __lockevent_inc(LOCKEVENT_ ##ev, true)#define lockevent_cond_inc(ev, c) __lockevent_inc(LOCKEVENT_ ##ev, c) static inline void __lockevent_add(enum lock_events event, int inc){	lockevent_percpu_add(lockevents[event], inc);} #define lockevent_add(ev, c)	__lockevent_add(LOCKEVENT_ ##ev, c) #else  /* CONFIG_LOCK_EVENT_COUNTS */ #define lockevent_inc(ev)#define lockevent_add(ev, c)#define lockevent_cond_inc(ev, c) #endif /* CONFIG_LOCK_EVENT_COUNTS */#endif /* __LOCKING_LOCK_EVENTS_H */