mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-15 09:46:46 +07:00
64b47e8fdb
When the system has only one CPU, lglock is effectively a spinlock; map it directly to spinlock to eliminate the indirection and duplicate code. In addition to removing overhead, this drops 1.6k of code with a defconfig modified to have !CONFIG_SMP, and 1.1k with a minimal config. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Howells <dhowells@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
77 lines
2.4 KiB
C
77 lines
2.4 KiB
C
/*
|
|
* Specialised local-global spinlock. Can only be declared as global variables
|
|
* to avoid overhead and keep things simple (and we don't want to start using
|
|
* these inside dynamically allocated structures).
|
|
*
|
|
* "local/global locks" (lglocks) can be used to:
|
|
*
|
|
* - Provide fast exclusive access to per-CPU data, with exclusive access to
|
|
* another CPU's data allowed but possibly subject to contention, and to
|
|
* provide very slow exclusive access to all per-CPU data.
|
|
* - Or to provide very fast and scalable read serialisation, and to provide
|
|
* very slow exclusive serialisation of data (not necessarily per-CPU data).
|
|
*
|
|
* Brlocks are also implemented as a short-hand notation for the latter use
|
|
* case.
|
|
*
|
|
* Copyright 2009, 2010, Nick Piggin, Novell Inc.
|
|
*/
|
|
#ifndef __LINUX_LGLOCK_H
|
|
#define __LINUX_LGLOCK_H
|
|
|
|
#include <linux/spinlock.h>
|
|
#include <linux/lockdep.h>
|
|
#include <linux/percpu.h>
|
|
#include <linux/cpu.h>
|
|
#include <linux/notifier.h>
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
#define LOCKDEP_INIT_MAP lockdep_init_map
|
|
#else
|
|
#define LOCKDEP_INIT_MAP(a, b, c, d)
|
|
#endif
|
|
|
|
struct lglock {
|
|
arch_spinlock_t __percpu *lock;
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
struct lock_class_key lock_key;
|
|
struct lockdep_map lock_dep_map;
|
|
#endif
|
|
};
|
|
|
|
#define DEFINE_LGLOCK(name) \
|
|
static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
|
|
= __ARCH_SPIN_LOCK_UNLOCKED; \
|
|
struct lglock name = { .lock = &name ## _lock }
|
|
|
|
#define DEFINE_STATIC_LGLOCK(name) \
|
|
static DEFINE_PER_CPU(arch_spinlock_t, name ## _lock) \
|
|
= __ARCH_SPIN_LOCK_UNLOCKED; \
|
|
static struct lglock name = { .lock = &name ## _lock }
|
|
|
|
void lg_lock_init(struct lglock *lg, char *name);
|
|
void lg_local_lock(struct lglock *lg);
|
|
void lg_local_unlock(struct lglock *lg);
|
|
void lg_local_lock_cpu(struct lglock *lg, int cpu);
|
|
void lg_local_unlock_cpu(struct lglock *lg, int cpu);
|
|
void lg_global_lock(struct lglock *lg);
|
|
void lg_global_unlock(struct lglock *lg);
|
|
|
|
#else
|
|
/* When !CONFIG_SMP, map lglock to spinlock */
|
|
#define lglock spinlock
|
|
#define DEFINE_LGLOCK(name) DEFINE_SPINLOCK(name)
|
|
#define DEFINE_STATIC_LGLOCK(name) static DEFINE_SPINLOCK(name)
|
|
#define lg_lock_init(lg, name) spin_lock_init(lg)
|
|
#define lg_local_lock spin_lock
|
|
#define lg_local_unlock spin_unlock
|
|
#define lg_local_lock_cpu(lg, cpu) spin_lock(lg)
|
|
#define lg_local_unlock_cpu(lg, cpu) spin_unlock(lg)
|
|
#define lg_global_lock spin_lock
|
|
#define lg_global_unlock spin_unlock
|
|
#endif
|
|
|
|
#endif
|