forked from KolibriOS/kolibrios
118 lines
3.1 KiB
C
118 lines
3.1 KiB
C
/*
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* kernel/locking/mutex.c
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*
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* Mutexes: blocking mutual exclusion locks
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*
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* Started by Ingo Molnar:
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*
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* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*
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* Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
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* David Howells for suggestions and improvements.
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*
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* - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline
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* from the -rt tree, where it was originally implemented for rtmutexes
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* by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale
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* and Sven Dietrich.
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*
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* Also see Documentation/mutex-design.txt.
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*/
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#include <linux/lockdep.h>
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#include <linux/mutex.h>
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#include <linux/ww_mutex.h>
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#include <linux/sched.h>
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#include <linux/export.h>
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#include <linux/spinlock.h>
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#include <syscall.h>
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/*
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* A negative mutex count indicates that waiters are sleeping waiting for the
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* mutex.
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*/
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#define MUTEX_SHOW_NO_WAITER(mutex) (atomic_read(&(mutex)->count) >= 0)
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void
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__mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
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{
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atomic_set(&lock->count, 1);
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// spin_lock_init(&lock->wait_lock);
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INIT_LIST_HEAD(&lock->wait_list);
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// mutex_clear_owner(lock);
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#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
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lock->osq = NULL;
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#endif
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}
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static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww,
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struct ww_acquire_ctx *ww_ctx)
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{
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#ifdef CONFIG_DEBUG_MUTEXES
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/*
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* If this WARN_ON triggers, you used ww_mutex_lock to acquire,
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* but released with a normal mutex_unlock in this call.
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*
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* This should never happen, always use ww_mutex_unlock.
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*/
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DEBUG_LOCKS_WARN_ON(ww->ctx);
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/*
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* Not quite done after calling ww_acquire_done() ?
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*/
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DEBUG_LOCKS_WARN_ON(ww_ctx->done_acquire);
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if (ww_ctx->contending_lock) {
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/*
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* After -EDEADLK you tried to
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* acquire a different ww_mutex? Bad!
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*/
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DEBUG_LOCKS_WARN_ON(ww_ctx->contending_lock != ww);
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/*
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* You called ww_mutex_lock after receiving -EDEADLK,
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* but 'forgot' to unlock everything else first?
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*/
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DEBUG_LOCKS_WARN_ON(ww_ctx->acquired > 0);
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ww_ctx->contending_lock = NULL;
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}
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/*
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* Naughty, using a different class will lead to undefined behavior!
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*/
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DEBUG_LOCKS_WARN_ON(ww_ctx->ww_class != ww->ww_class);
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#endif
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ww_ctx->acquired++;
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}
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void ww_mutex_unlock(struct ww_mutex *lock)
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{
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/*
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* The unlocking fastpath is the 0->1 transition from 'locked'
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* into 'unlocked' state:
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*/
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if (lock->ctx) {
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if (lock->ctx->acquired > 0)
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lock->ctx->acquired--;
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lock->ctx = NULL;
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}
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MutexUnlock(&lock->base);
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}
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int __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
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{
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MutexLock(&lock->base);
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ww_mutex_lock_acquired(lock, ctx);
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lock->ctx = ctx;
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return 0;
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}
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int __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
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{
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MutexLock(&lock->base);
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ww_mutex_lock_acquired(lock, ctx);
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lock->ctx = ctx;
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return 0;
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}
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