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six locks: Split out seq, use atomic_t instead of atomic64_t 

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-05-22 00:17:40 -04:00
parent a4e9e1f0cb
commit 2804d0f15b
2 changed files with 58 additions and 71 deletions
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124
fs/bcachefs/six.c
View File

@ -32,25 +32,18 @@ static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type);
* bits 29-30 has read waiters
* bits 30-31 has intent waiters
* bits 31-32 has write waiters
* bits 32-64 sequence number: incremented on every write lock or
* unlock, thus bit 33 (sequence number odd) indicates
* lock is currently held for write
*/
#define SIX_STATE_READ_OFFSET 0
#define SIX_STATE_READ_BITS 26
#define SIX_STATE_READ_LOCK ~(~0ULL << 26)
#define SIX_STATE_INTENT_HELD (1ULL << 26)
#define SIX_STATE_WRITE_LOCK (1ULL << 27)
#define SIX_STATE_NOSPIN (1ULL << 28)
#define SIX_STATE_WAITING_READ (1ULL << (29 + SIX_LOCK_read))
#define SIX_STATE_WAITING_INTENT (1ULL << (29 + SIX_LOCK_intent))
#define SIX_STATE_WAITING_WRITE (1ULL << (29 + SIX_LOCK_write))
#define SIX_STATE_SEQ_OFFSET 32
#define SIX_STATE_SEQ_BITS 32
#define SIX_STATE_SEQ (~0ULL << 32)
#define SIX_STATE_READ_LOCK ~(~0U << 26)
#define SIX_STATE_INTENT_HELD (1U << 26)
#define SIX_STATE_WRITE_LOCK (1U << 27)
#define SIX_STATE_NOSPIN (1U << 28)
#define SIX_STATE_WAITING_READ (1U << (29 + SIX_LOCK_read))
#define SIX_STATE_WAITING_INTENT (1U << (29 + SIX_LOCK_intent))
#define SIX_STATE_WAITING_WRITE (1U << (29 + SIX_LOCK_write))
#define SIX_LOCK_HELD_read SIX_STATE_READ_LOCK
#define SIX_LOCK_HELD_intent SIX_STATE_INTENT_HELD
@ -58,13 +51,13 @@ static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type);
struct six_lock_vals {
/* Value we add to the lock in order to take the lock: */
u64 lock_val;
u32 lock_val;
/* If the lock has this value (used as a mask), taking the lock fails: */
u64 lock_fail;
u32 lock_fail;
/* Mask that indicates lock is held for this type: */
u64 held_mask;
u32 held_mask;
/* Waitlist we wakeup when releasing the lock: */
enum six_lock_type unlock_wakeup;
@ -72,7 +65,7 @@ struct six_lock_vals {
static const struct six_lock_vals l[] = {
[SIX_LOCK_read] = {
.lock_val = 1ULL << SIX_STATE_READ_OFFSET,
.lock_val = 1U << SIX_STATE_READ_OFFSET,
.lock_fail = SIX_LOCK_HELD_write,
.held_mask = SIX_LOCK_HELD_read,
.unlock_wakeup = SIX_LOCK_write,
@ -91,25 +84,20 @@ static const struct six_lock_vals l[] = {
},
};
static inline u32 six_state_seq(u64 state)
static inline void six_set_bitmask(struct six_lock *lock, u32 mask)
{
return state >> SIX_STATE_SEQ_OFFSET;
if ((atomic_read(&lock->state) & mask) != mask)
atomic_or(mask, &lock->state);
}
static inline void six_set_bitmask(struct six_lock *lock, u64 mask)
static inline void six_clear_bitmask(struct six_lock *lock, u32 mask)
{
if ((atomic64_read(&lock->state) & mask) != mask)
atomic64_or(mask, &lock->state);
}
static inline void six_clear_bitmask(struct six_lock *lock, u64 mask)
{
if (atomic64_read(&lock->state) & mask)
atomic64_and(~mask, &lock->state);
if (atomic_read(&lock->state) & mask)
atomic_and(~mask, &lock->state);
}
static inline void six_set_owner(struct six_lock *lock, enum six_lock_type type,
u64 old, struct task_struct *owner)
u32 old, struct task_struct *owner)
{
if (type != SIX_LOCK_intent)
return;
@ -145,13 +133,11 @@ static int __do_six_trylock(struct six_lock *lock, enum six_lock_type type,
struct task_struct *task, bool try)
{
int ret;
u64 old, new, v;
u32 old, new, v;
EBUG_ON(type == SIX_LOCK_write && lock->owner != task);
EBUG_ON(type == SIX_LOCK_write &&
(try != !(atomic64_read(&lock->state) & SIX_LOCK_HELD_write)));
EBUG_ON(type == SIX_LOCK_write &&
(try != !(atomic64_read(&lock->state) & SIX_STATE_WRITE_LOCK)));
(try != !(atomic_read(&lock->state) & SIX_STATE_WRITE_LOCK)));
/*
* Percpu reader mode:
@ -186,7 +172,7 @@ static int __do_six_trylock(struct six_lock *lock, enum six_lock_type type,
smp_mb();
old = atomic64_read(&lock->state);
old = atomic_read(&lock->state);
ret = !(old & l[type].lock_fail);
this_cpu_sub(*lock->readers, !ret);
@ -196,19 +182,19 @@ static int __do_six_trylock(struct six_lock *lock, enum six_lock_type type,
ret = -1 - SIX_LOCK_write;
} else if (type == SIX_LOCK_write && lock->readers) {
if (try) {
atomic64_add(SIX_STATE_WRITE_LOCK, &lock->state);
atomic_add(SIX_STATE_WRITE_LOCK, &lock->state);
smp_mb__after_atomic();
}
ret = !pcpu_read_count(lock);
if (try && !ret) {
old = atomic64_sub_return(SIX_STATE_WRITE_LOCK, &lock->state);
old = atomic_sub_return(SIX_STATE_WRITE_LOCK, &lock->state);
if (old & SIX_STATE_WAITING_READ)
ret = -1 - SIX_LOCK_read;
}
} else {
v = atomic64_read(&lock->state);
v = atomic_read(&lock->state);
do {
new = old = v;
@ -218,16 +204,16 @@ static int __do_six_trylock(struct six_lock *lock, enum six_lock_type type,
break;
new += l[type].lock_val;
} while ((v = atomic64_cmpxchg_acquire(&lock->state, old, new)) != old);
} while ((v = atomic_cmpxchg_acquire(&lock->state, old, new)) != old);
EBUG_ON(ret && !(atomic64_read(&lock->state) & l[type].held_mask));
EBUG_ON(ret && !(atomic_read(&lock->state) & l[type].held_mask));
}
if (ret > 0)
six_set_owner(lock, type, old, task);
EBUG_ON(type == SIX_LOCK_write && try && ret <= 0 &&
(atomic64_read(&lock->state) & SIX_STATE_WRITE_LOCK));
(atomic_read(&lock->state) & SIX_STATE_WRITE_LOCK));
return ret;
}
@ -277,7 +263,7 @@ unlock:
}
__always_inline
static void six_lock_wakeup(struct six_lock *lock, u64 state,
static void six_lock_wakeup(struct six_lock *lock, u32 state,
enum six_lock_type lock_type)
{
if (lock_type == SIX_LOCK_write && (state & SIX_LOCK_HELD_read))
@ -317,7 +303,8 @@ bool six_trylock_ip(struct six_lock *lock, enum six_lock_type type, unsigned lon
if (type != SIX_LOCK_write)
six_acquire(&lock->dep_map, 1, type == SIX_LOCK_read, ip);
else
atomic64_add(1ULL << SIX_STATE_SEQ_OFFSET, &lock->state);
lock->seq++;
return true;
}
EXPORT_SYMBOL_GPL(six_trylock_ip);
@ -482,12 +469,12 @@ static int six_lock_slowpath(struct six_lock *lock, enum six_lock_type type,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip)
{
u64 old;
u32 old;
int ret = 0;
if (type == SIX_LOCK_write) {
EBUG_ON(atomic64_read(&lock->state) & SIX_STATE_WRITE_LOCK);
atomic64_add(SIX_STATE_WRITE_LOCK, &lock->state);
EBUG_ON(atomic_read(&lock->state) & SIX_STATE_WRITE_LOCK);
atomic_add(SIX_STATE_WRITE_LOCK, &lock->state);
smp_mb__after_atomic();
}
@ -609,8 +596,7 @@ int six_lock_ip_waiter(struct six_lock *lock, enum six_lock_type type,
ret = do_six_trylock(lock, type, true) ? 0
: six_lock_slowpath(lock, type, wait, should_sleep_fn, p, ip);
if (!ret && type == SIX_LOCK_write)
atomic64_add(1ULL << SIX_STATE_SEQ_OFFSET, &lock->state);
lock->seq += !ret && type == SIX_LOCK_write;
if (ret && type != SIX_LOCK_write)
six_release(&lock->dep_map, ip);
@ -624,7 +610,7 @@ EXPORT_SYMBOL_GPL(six_lock_ip_waiter);
__always_inline
static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type)
{
u64 state;
u32 state;
if (type == SIX_LOCK_intent)
lock->owner = NULL;
@ -634,15 +620,15 @@ static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type)
smp_mb(); /* unlock barrier */
this_cpu_dec(*lock->readers);
smp_mb(); /* between unlocking and checking for waiters */
state = atomic64_read(&lock->state);
state = atomic_read(&lock->state);
} else {
u64 v = l[type].lock_val;
u32 v = l[type].lock_val;
if (type != SIX_LOCK_read)
v += atomic64_read(&lock->state) & SIX_STATE_NOSPIN;
v += atomic_read(&lock->state) & SIX_STATE_NOSPIN;
EBUG_ON(!(atomic64_read(&lock->state) & l[type].held_mask));
state = atomic64_sub_return_release(v, &lock->state);
EBUG_ON(!(atomic_read(&lock->state) & l[type].held_mask));
state = atomic_sub_return_release(v, &lock->state);
}
six_lock_wakeup(lock, state, l[type].unlock_wakeup);
@ -666,7 +652,7 @@ static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type)
void six_unlock_ip(struct six_lock *lock, enum six_lock_type type, unsigned long ip)
{
EBUG_ON(type == SIX_LOCK_write &&
!(atomic64_read(&lock->state) & SIX_LOCK_HELD_intent));
!(atomic_read(&lock->state) & SIX_LOCK_HELD_intent));
EBUG_ON((type == SIX_LOCK_write ||
type == SIX_LOCK_intent) &&
lock->owner != current);
@ -674,7 +660,7 @@ void six_unlock_ip(struct six_lock *lock, enum six_lock_type type, unsigned long
if (type != SIX_LOCK_write)
six_release(&lock->dep_map, ip);
else
atomic64_add(1ULL << SIX_STATE_SEQ_OFFSET, &lock->state);
lock->seq++;
if (type == SIX_LOCK_intent &&
lock->intent_lock_recurse) {
@ -710,7 +696,7 @@ EXPORT_SYMBOL_GPL(six_lock_downgrade);
*/
bool six_lock_tryupgrade(struct six_lock *lock)
{
u64 old, new, v = atomic64_read(&lock->state);
u32 old, new, v = atomic_read(&lock->state);
do {
new = old = v;
@ -724,7 +710,7 @@ bool six_lock_tryupgrade(struct six_lock *lock)
}
new |= SIX_LOCK_HELD_intent;
} while ((v = atomic64_cmpxchg_acquire(&lock->state, old, new)) != old);
} while ((v = atomic_cmpxchg_acquire(&lock->state, old, new)) != old);
if (lock->readers)
this_cpu_dec(*lock->readers);
@ -786,14 +772,14 @@ void six_lock_increment(struct six_lock *lock, enum six_lock_type type)
if (lock->readers) {
this_cpu_inc(*lock->readers);
} else {
EBUG_ON(!(atomic64_read(&lock->state) &
EBUG_ON(!(atomic_read(&lock->state) &
(SIX_LOCK_HELD_read|
SIX_LOCK_HELD_intent)));
atomic64_add(l[type].lock_val, &lock->state);
atomic_add(l[type].lock_val, &lock->state);
}
break;
case SIX_LOCK_intent:
EBUG_ON(!(atomic64_read(&lock->state) & SIX_LOCK_HELD_intent));
EBUG_ON(!(atomic_read(&lock->state) & SIX_LOCK_HELD_intent));
lock->intent_lock_recurse++;
break;
case SIX_LOCK_write:
@ -815,7 +801,7 @@ EXPORT_SYMBOL_GPL(six_lock_increment);
*/
void six_lock_wakeup_all(struct six_lock *lock)
{
u64 state = atomic64_read(&lock->state);
u32 state = atomic_read(&lock->state);
struct six_lock_waiter *w;
six_lock_wakeup(lock, state, SIX_LOCK_read);
@ -840,11 +826,11 @@ struct six_lock_count six_lock_counts(struct six_lock *lock)
struct six_lock_count ret;
ret.n[SIX_LOCK_read] = !lock->readers
? atomic64_read(&lock->state) & SIX_STATE_READ_LOCK
? atomic_read(&lock->state) & SIX_STATE_READ_LOCK
: pcpu_read_count(lock);
ret.n[SIX_LOCK_intent] = !!(atomic64_read(&lock->state) & SIX_LOCK_HELD_intent) +
ret.n[SIX_LOCK_intent] = !!(atomic_read(&lock->state) & SIX_LOCK_HELD_intent) +
lock->intent_lock_recurse;
ret.n[SIX_LOCK_write] = !!(atomic64_read(&lock->state) & SIX_LOCK_HELD_write);
ret.n[SIX_LOCK_write] = !!(atomic_read(&lock->state) & SIX_LOCK_HELD_write);
return ret;
}
@ -875,9 +861,9 @@ void six_lock_readers_add(struct six_lock *lock, int nr)
if (lock->readers) {
this_cpu_add(*lock->readers, nr);
} else {
EBUG_ON((int) (atomic64_read(&lock->state) & SIX_STATE_READ_LOCK) + nr < 0);
EBUG_ON((int) (atomic_read(&lock->state) & SIX_STATE_READ_LOCK) + nr < 0);
/* reader count starts at bit 0 */
atomic64_add(nr, &lock->state);
atomic_add(nr, &lock->state);
}
}
EXPORT_SYMBOL_GPL(six_lock_readers_add);
@ -892,7 +878,7 @@ EXPORT_SYMBOL_GPL(six_lock_readers_add);
void six_lock_exit(struct six_lock *lock)
{
WARN_ON(lock->readers && pcpu_read_count(lock));
WARN_ON(atomic64_read(&lock->state) & SIX_LOCK_HELD_read);
WARN_ON(atomic_read(&lock->state) & SIX_LOCK_HELD_read);
free_percpu(lock->readers);
lock->readers = NULL;
@ -902,7 +888,7 @@ EXPORT_SYMBOL_GPL(six_lock_exit);
void __six_lock_init(struct six_lock *lock, const char *name,
struct lock_class_key *key, enum six_lock_init_flags flags)
{
atomic64_set(&lock->state, 0);
atomic_set(&lock->state, 0);
raw_spin_lock_init(&lock->wait_lock);
INIT_LIST_HEAD(&lock->wait_list);
#ifdef CONFIG_DEBUG_LOCK_ALLOC

5
fs/bcachefs/six.h
View File

@ -138,7 +138,8 @@ enum six_lock_type {
};
struct six_lock {
atomic64_t state;
atomic_t state;
u32 seq;
unsigned intent_lock_recurse;
struct task_struct *owner;
unsigned __percpu *readers;
@ -196,7 +197,7 @@ do { \
*/
static inline u32 six_lock_seq(const struct six_lock *lock)
{
return atomic64_read(&lock->state) >> 32;
return lock->seq;
}
bool six_trylock_ip(struct six_lock *lock, enum six_lock_type type, unsigned long ip);