linux/kernel/locking/lock_events.h
Waiman Long 3774b28d8f locking/qspinlock: Always evaluate lockevent* non-event parameter once
The 'inc' parameter of lockevent_add() and the cond parameter of
lockevent_cond_inc() are only evaluated when CONFIG_LOCK_EVENT_COUNTS
is on. That can cause problem if those parameters are expressions
with side effect like a "++". Fix this by evaluating those non-event
parameters once even if CONFIG_LOCK_EVENT_COUNTS is off. This will also
eliminate the need of the __maybe_unused attribute to the wait_early
local variable in pv_wait_node().

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20240319005004.1692705-1-longman@redhat.com
2024-03-21 20:45:17 +01:00

65 lines
1.8 KiB
C

/* 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]);
/*
* Increment the statistical counters. use raw_cpu_inc() because of lower
* overhead and we don't care if we loose the occasional update.
*/
static inline void __lockevent_inc(enum lock_events event, bool cond)
{
if (cond)
raw_cpu_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)
{
raw_cpu_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) do { (void)(c); } while (0)
#define lockevent_cond_inc(ev, c) do { (void)(c); } while (0)
#endif /* CONFIG_LOCK_EVENT_COUNTS */
ssize_t lockevent_read(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos);
#endif /* __LOCKING_LOCK_EVENTS_H */