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/*
* Copyright (c) 2015-2017, Linaro Limited
*/
#include <kernel/mutex.h>
#include <kernel/panic.h>
#include <kernel/spinlock.h>
#include <kernel/thread.h>
#include <trace.h>
#include "mutex_lockdep.h"
void mutex_init(struct mutex *m)
{
*m = (struct mutex)MUTEX_INITIALIZER;
}
static void __mutex_lock(struct mutex *m, const char *fname, int lineno)
{
assert_have_no_spinlock();
assert(thread_get_id_may_fail() != -1);
assert(thread_is_in_normal_mode());
mutex_lock_check(m);
while (true) {
uint32_t old_itr_status;
bool can_lock;
struct wait_queue_elem wqe;
/*
* If the mutex is locked we need to initialize the wqe
* before releasing the spinlock to guarantee that we don't
* miss the wakeup from mutex_unlock().
*
* If the mutex is unlocked we don't need to use the wqe at
* all.
*/
old_itr_status = cpu_spin_lock_xsave(&m->spin_lock);
can_lock = !m->state;
if (!can_lock) {
wq_wait_init(&m->wq, &wqe, false /* wait_read */);
} else {
m->state = -1; /* write locked */
}
cpu_spin_unlock_xrestore(&m->spin_lock, old_itr_status);
if (!can_lock) {
/*
* Someone else is holding the lock, wait in normal
* world for the lock to become available.
*/
wq_wait_final(&m->wq, &wqe, m, fname, lineno);
} else
return;
}
}
static void __mutex_unlock(struct mutex *m, const char *fname, int lineno)
{
uint32_t old_itr_status;
assert_have_no_spinlock();
assert(thread_get_id_may_fail() != -1);
mutex_unlock_check(m);
old_itr_status = cpu_spin_lock_xsave(&m->spin_lock);
if (!m->state)
panic();
m->state = 0;
cpu_spin_unlock_xrestore(&m->spin_lock, old_itr_status);
wq_wake_next(&m->wq, m, fname, lineno);
}
static bool __mutex_trylock(struct mutex *m, const char *fname __unused,
int lineno __unused)
{
uint32_t old_itr_status;
bool can_lock_write;
assert_have_no_spinlock();
assert(thread_get_id_may_fail() != -1);
old_itr_status = cpu_spin_lock_xsave(&m->spin_lock);
can_lock_write = !m->state;
if (can_lock_write)
m->state = -1;
cpu_spin_unlock_xrestore(&m->spin_lock, old_itr_status);
if (can_lock_write)
mutex_trylock_check(m);
return can_lock_write;
}
static void __mutex_read_unlock(struct mutex *m, const char *fname, int lineno)
{
uint32_t old_itr_status;
short new_state;
assert_have_no_spinlock();
assert(thread_get_id_may_fail() != -1);
old_itr_status = cpu_spin_lock_xsave(&m->spin_lock);
if (m->state <= 0)
panic();
m->state--;
new_state = m->state;
cpu_spin_unlock_xrestore(&m->spin_lock, old_itr_status);
/* Wake eventual waiters if the mutex was unlocked */
if (!new_state)
wq_wake_next(&m->wq, m, fname, lineno);
}
static void __mutex_read_lock(struct mutex *m, const char *fname, int lineno)
{
assert_have_no_spinlock();
assert(thread_get_id_may_fail() != -1);
assert(thread_is_in_normal_mode());
while (true) {
uint32_t old_itr_status;
bool can_lock;
struct wait_queue_elem wqe;
/*
* If the mutex is locked we need to initialize the wqe
* before releasing the spinlock to guarantee that we don't
* miss the wakeup from mutex_unlock().
*
* If the mutex is unlocked we don't need to use the wqe at
* all.
*/
old_itr_status = cpu_spin_lock_xsave(&m->spin_lock);
can_lock = m->state != -1;
if (!can_lock) {
wq_wait_init(&m->wq, &wqe, true /* wait_read */);
} else {
m->state++; /* read_locked */
}
cpu_spin_unlock_xrestore(&m->spin_lock, old_itr_status);
if (!can_lock) {
/*
* Someone else is holding the lock, wait in normal
* world for the lock to become available.
*/
wq_wait_final(&m->wq, &wqe, m, fname, lineno);
} else
return;
}
}
static bool __mutex_read_trylock(struct mutex *m, const char *fname __unused,
int lineno __unused)
{
uint32_t old_itr_status;
bool can_lock;
assert_have_no_spinlock();
assert(thread_get_id_may_fail() != -1);
assert(thread_is_in_normal_mode());
old_itr_status = cpu_spin_lock_xsave(&m->spin_lock);
can_lock = m->state != -1;
if (can_lock)
m->state++;
cpu_spin_unlock_xrestore(&m->spin_lock, old_itr_status);
return can_lock;
}
#ifdef CFG_MUTEX_DEBUG
void mutex_unlock_debug(struct mutex *m, const char *fname, int lineno)
{
__mutex_unlock(m, fname, lineno);
}
void mutex_lock_debug(struct mutex *m, const char *fname, int lineno)
{
__mutex_lock(m, fname, lineno);
}
bool mutex_trylock_debug(struct mutex *m, const char *fname, int lineno)
{
return __mutex_trylock(m, fname, lineno);
}
void mutex_read_unlock_debug(struct mutex *m, const char *fname, int lineno)
{
__mutex_read_unlock(m, fname, lineno);
}
void mutex_read_lock_debug(struct mutex *m, const char *fname, int lineno)
{
__mutex_read_lock(m, fname, lineno);
}
bool mutex_read_trylock_debug(struct mutex *m, const char *fname, int lineno)
{
return __mutex_read_trylock(m, fname, lineno);
}
#else
void mutex_unlock(struct mutex *m)
{
__mutex_unlock(m, NULL, -1);
}
void mutex_lock(struct mutex *m)
{
__mutex_lock(m, NULL, -1);
}
bool mutex_trylock(struct mutex *m)
{
return __mutex_trylock(m, NULL, -1);
}
void mutex_read_unlock(struct mutex *m)
{
__mutex_read_unlock(m, NULL, -1);
}
void mutex_read_lock(struct mutex *m)
{
__mutex_read_lock(m, NULL, -1);
}
bool mutex_read_trylock(struct mutex *m)
{
return __mutex_read_trylock(m, NULL, -1);
}
#endif
void mutex_destroy(struct mutex *m)
{
/*
* Caller guarantees that no one will try to take the mutex so
* there's no need to take the spinlock before accessing it.
*/
if (m->state)
panic();
if (!wq_is_empty(&m->wq))
panic("waitqueue not empty");
mutex_destroy_check(m);
}
void condvar_init(struct condvar *cv)
{
*cv = (struct condvar)CONDVAR_INITIALIZER;
}
void condvar_destroy(struct condvar *cv)
{
if (cv->m && wq_have_condvar(&cv->m->wq, cv))
panic();
condvar_init(cv);
}
static void cv_signal(struct condvar *cv, bool only_one, const char *fname,
int lineno)
{
uint32_t old_itr_status;
struct mutex *m;
old_itr_status = cpu_spin_lock_xsave(&cv->spin_lock);
m = cv->m;
cpu_spin_unlock_xrestore(&cv->spin_lock, old_itr_status);
if (m)
wq_promote_condvar(&m->wq, cv, only_one, m, fname, lineno);
}
#ifdef CFG_MUTEX_DEBUG
void condvar_signal_debug(struct condvar *cv, const char *fname, int lineno)
{
cv_signal(cv, true /* only one */, fname, lineno);
}
void condvar_broadcast_debug(struct condvar *cv, const char *fname, int lineno)
{
cv_signal(cv, false /* all */, fname, lineno);
}
#else
void condvar_signal(struct condvar *cv)
{
cv_signal(cv, true /* only one */, NULL, -1);
}
void condvar_broadcast(struct condvar *cv)
{
cv_signal(cv, false /* all */, NULL, -1);
}
#endif /*CFG_MUTEX_DEBUG*/
static void __condvar_wait(struct condvar *cv, struct mutex *m,
const char *fname, int lineno)
{
uint32_t old_itr_status;
struct wait_queue_elem wqe;
short old_state;
short new_state;
mutex_unlock_check(m);
/* Link this condvar to this mutex until reinitialized */
old_itr_status = cpu_spin_lock_xsave(&cv->spin_lock);
if (cv->m && cv->m != m)
panic("invalid mutex");
cv->m = m;
cpu_spin_unlock(&cv->spin_lock);
cpu_spin_lock(&m->spin_lock);
if (!m->state)
panic();
old_state = m->state;
/* Add to mutex wait queue as a condvar waiter */
wq_wait_init_condvar(&m->wq, &wqe, cv, m->state > 0);
if (m->state > 1) {
/* Multiple read locks, remove one */
m->state--;
} else {
/* Only one lock (read or write), unlock the mutex */
m->state = 0;
}
new_state = m->state;
cpu_spin_unlock_xrestore(&m->spin_lock, old_itr_status);
/* Wake eventual waiters if the mutex was unlocked */
if (!new_state)
wq_wake_next(&m->wq, m, fname, lineno);
wq_wait_final(&m->wq, &wqe, m, fname, lineno);
if (old_state > 0)
mutex_read_lock(m);
else
mutex_lock(m);
}
#ifdef CFG_MUTEX_DEBUG
void condvar_wait_debug(struct condvar *cv, struct mutex *m,
const char *fname, int lineno)
{
__condvar_wait(cv, m, fname, lineno);
}
#else
void condvar_wait(struct condvar *cv, struct mutex *m)
{
__condvar_wait(cv, m, NULL, -1);
}
#endif
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