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six locks: Documentation, renaming

Browse Source 
- Expanded and revamped overview documentation in six.h, giving an
   overview of all features
 - docbook-comments for all external interfaces
 - Rename some functions for simplicity, i.e.
   six_lock_ip_type() -> six_lock_ip()

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-05-21 15:40:40 -04:00
parent 1fb4fe6317
commit 91d16f16d0
3 changed files with 390 additions and 120 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/bcachefs/btree_locking.h
View File

@ -205,8 +205,8 @@ static inline int __btree_node_lock_nopath(struct btree_trans *trans,
trans->lock_must_abort = false;
trans->locking = b;
ret = six_lock_type_ip_waiter(&b->lock, type, &trans->locking_wait,
bch2_six_check_for_deadlock, trans, ip);
ret = six_lock_ip_waiter(&b->lock, type, &trans->locking_wait,
bch2_six_check_for_deadlock, trans, ip);
WRITE_ONCE(trans->locking, NULL);
WRITE_ONCE(trans->locking_wait.start_time, 0);
return ret;

218
fs/bcachefs/six.c
View File

@ -193,10 +193,8 @@ static inline unsigned pcpu_read_count(struct six_lock *lock)
return read_count;
}
static int __do_six_trylock_type(struct six_lock *lock,
enum six_lock_type type,
struct task_struct *task,
bool try)
static int __do_six_trylock(struct six_lock *lock, enum six_lock_type type,
struct task_struct *task, bool try)
{
const struct six_lock_vals l[] = LOCK_VALS;
int ret;
@ -316,7 +314,7 @@ again:
goto unlock;
saw_one = true;
ret = __do_six_trylock_type(lock, lock_type, w->task, false);
ret = __do_six_trylock(lock, lock_type, w->task, false);
if (ret <= 0)
goto unlock;
@ -355,32 +353,48 @@ static void six_lock_wakeup(struct six_lock *lock, u64 state,
}
__always_inline
static bool do_six_trylock_type(struct six_lock *lock,
enum six_lock_type type,
bool try)
static bool do_six_trylock(struct six_lock *lock, enum six_lock_type type, bool try)
{
int ret;
ret = __do_six_trylock_type(lock, type, current, try);
ret = __do_six_trylock(lock, type, current, try);
if (ret < 0)
__six_lock_wakeup(lock, -ret - 1);
return ret > 0;
}
bool six_trylock_ip_type(struct six_lock *lock, enum six_lock_type type,
unsigned long ip)
/**
* six_trylock_ip - attempt to take a six lock without blocking
* @lock: lock to take
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
* @ip: ip parameter for lockdep/lockstat, i.e. _THIS_IP_
*
* Return: true on success, false on failure.
*/
bool six_trylock_ip(struct six_lock *lock, enum six_lock_type type, unsigned long ip)
{
if (!do_six_trylock_type(lock, type, true))
if (!do_six_trylock(lock, type, true))
return false;
if (type != SIX_LOCK_write)
six_acquire(&lock->dep_map, 1, type == SIX_LOCK_read, ip);
return true;
}
EXPORT_SYMBOL_GPL(six_trylock_ip);
bool six_relock_ip_type(struct six_lock *lock, enum six_lock_type type,
unsigned seq, unsigned long ip)
/**
* six_relock_ip - attempt to re-take a lock that was held previously
* @lock: lock to take
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
* @seq: lock sequence number obtained from six_lock_seq() while lock was
* held previously
* @ip: ip parameter for lockdep/lockstat, i.e. _THIS_IP_
*
* Return: true on success, false on failure.
*/
bool six_relock_ip(struct six_lock *lock, enum six_lock_type type,
unsigned seq, unsigned long ip)
{
const struct six_lock_vals l[] = LOCK_VALS;
u64 old, v;
@ -421,15 +435,15 @@ bool six_relock_ip_type(struct six_lock *lock, enum six_lock_type type,
if ((old & l[type].lock_fail) || six_state_seq(old) != seq)
return false;
} while ((v = atomic64_cmpxchg_acquire(&lock->state,
old,
old + l[type].lock_val)) != old);
old,
old + l[type].lock_val)) != old);
six_set_owner(lock, type, old, current);
if (type != SIX_LOCK_write)
six_acquire(&lock->dep_map, 1, type == SIX_LOCK_read, ip);
return true;
}
EXPORT_SYMBOL_GPL(six_relock_ip_type);
EXPORT_SYMBOL_GPL(six_relock_ip);
#ifdef CONFIG_SIX_LOCK_SPIN_ON_OWNER
@ -512,7 +526,7 @@ static inline bool six_optimistic_spin(struct six_lock *lock, enum six_lock_type
if (owner && !six_spin_on_owner(lock, owner, end_time))
break;
if (do_six_trylock_type(lock, type, false)) {
if (do_six_trylock(lock, type, false)) {
osq_unlock(&lock->osq);
preempt_enable();
return true;
@ -561,10 +575,10 @@ static inline bool six_optimistic_spin(struct six_lock *lock, enum six_lock_type
#endif
noinline
static int __six_lock_type_slowpath(struct six_lock *lock, enum six_lock_type type,
struct six_lock_waiter *wait,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip)
static int six_lock_slowpath(struct six_lock *lock, enum six_lock_type type,
struct six_lock_waiter *wait,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip)
{
u64 old;
int ret = 0;
@ -587,10 +601,10 @@ static int __six_lock_type_slowpath(struct six_lock *lock, enum six_lock_type ty
raw_spin_lock(&lock->wait_lock);
six_set_bitmask(lock, SIX_STATE_WAITING_READ << type);
/*
* Retry taking the lock after taking waitlist lock, have raced with an
* unlock:
* Retry taking the lock after taking waitlist lock, in case we raced
* with an unlock:
*/
ret = __do_six_trylock_type(lock, type, current, false);
ret = __do_six_trylock(lock, type, current, false);
if (ret <= 0) {
wait->start_time = local_clock();
@ -648,10 +662,40 @@ out:
return ret;
}
int six_lock_type_ip_waiter(struct six_lock *lock, enum six_lock_type type,
struct six_lock_waiter *wait,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip)
/**
* six_lock_ip_waiter - take a lock, with full waitlist interface
* @lock: lock to take
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
* @wait: pointer to wait object, which will be added to lock's waitlist
* @should_sleep_fn: callback run after adding to waitlist, immediately prior
* to scheduling
* @p: passed through to @should_sleep_fn
* @ip: ip parameter for lockdep/lockstat, i.e. _THIS_IP_
*
* This is the most general six_lock() variant, with parameters to support full
* cycle detection for deadlock avoidance.
*
* The code calling this function must implement tracking of held locks, and the
* @wait object should be embedded into the struct that tracks held locks -
* which must also be accessible in a thread-safe way.
*
* @should_sleep_fn should invoke the cycle detector; it should walk each
* lock's waiters, and for each waiter recursively walk their held locks.
*
* When this function must block, @wait will be added to @lock's waitlist before
* calling trylock, and before calling @should_sleep_fn, and @wait will not be
* removed from the lock waitlist until the lock has been successfully acquired,
* or we abort.
*
* @wait.start_time will be monotonically increasing for any given waitlist, and
* thus may be used as a loop cursor.
*
* Return: 0 on success, or the return code from @should_sleep_fn on failure.
*/
int six_lock_ip_waiter(struct six_lock *lock, enum six_lock_type type,
struct six_lock_waiter *wait,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip)
{
int ret;
@ -660,8 +704,8 @@ int six_lock_type_ip_waiter(struct six_lock *lock, enum six_lock_type type,
if (type != SIX_LOCK_write)
six_acquire(&lock->dep_map, 0, type == SIX_LOCK_read, ip);
ret = do_six_trylock_type(lock, type, true) ? 0
: __six_lock_type_slowpath(lock, type, wait, should_sleep_fn, p, ip);
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)
six_release(&lock->dep_map, ip);
@ -670,7 +714,7 @@ int six_lock_type_ip_waiter(struct six_lock *lock, enum six_lock_type type,
return ret;
}
EXPORT_SYMBOL_GPL(six_lock_type_ip_waiter);
EXPORT_SYMBOL_GPL(six_lock_ip_waiter);
__always_inline
static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type)
@ -700,7 +744,22 @@ static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type)
six_lock_wakeup(lock, state, l[type].unlock_wakeup);
}
void six_unlock_ip_type(struct six_lock *lock, enum six_lock_type type, unsigned long ip)
/**
* six_unlock_ip - drop a six lock
* @lock: lock to unlock
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
* @ip: ip parameter for lockdep/lockstat, i.e. _THIS_IP_
*
* When a lock is held multiple times (because six_lock_incement()) was used),
* this decrements the 'lock held' counter by one.
*
* For example:
* six_lock_read(&foo->lock); read count 1
* six_lock_increment(&foo->lock, SIX_LOCK_read); read count 2
* six_lock_unlock(&foo->lock, SIX_LOCK_read); read count 1
* six_lock_unlock(&foo->lock, SIX_LOCK_read); read count 0
*/
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));
@ -719,9 +778,14 @@ void six_unlock_ip_type(struct six_lock *lock, enum six_lock_type type, unsigned
do_six_unlock_type(lock, type);
}
EXPORT_SYMBOL_GPL(six_unlock_ip_type);
EXPORT_SYMBOL_GPL(six_unlock_ip);
/* Convert from intent to read: */
/**
* six_lock_downgrade - convert an intent lock to a read lock
* @lock: lock to dowgrade
*
* @lock will have read count incremented and intent count decremented
*/
void six_lock_downgrade(struct six_lock *lock)
{
six_lock_increment(lock, SIX_LOCK_read);
@ -729,6 +793,15 @@ void six_lock_downgrade(struct six_lock *lock)
}
EXPORT_SYMBOL_GPL(six_lock_downgrade);
/**
* six_lock_tryupgrade - attempt to convert read lock to an intent lock
* @lock: lock to upgrade
*
* On success, @lock will have intent count incremented and read count
* decremented
*
* Return: true on success, false on failure
*/
bool six_lock_tryupgrade(struct six_lock *lock)
{
const struct six_lock_vals l[] = LOCK_VALS;
@ -757,6 +830,17 @@ bool six_lock_tryupgrade(struct six_lock *lock)
}
EXPORT_SYMBOL_GPL(six_lock_tryupgrade);
/**
* six_trylock_convert - attempt to convert a held lock from one type to another
* @lock: lock to upgrade
* @from: SIX_LOCK_read or SIX_LOCK_intent
* @to: SIX_LOCK_read or SIX_LOCK_intent
*
* On success, @lock will have intent count incremented and read count
* decremented
*
* Return: true on success, false on failure
*/
bool six_trylock_convert(struct six_lock *lock,
enum six_lock_type from,
enum six_lock_type to)
@ -775,9 +859,16 @@ bool six_trylock_convert(struct six_lock *lock,
}
EXPORT_SYMBOL_GPL(six_trylock_convert);
/*
* Increment read/intent lock count, assuming we already have it read or intent
* locked:
/**
* six_lock_increment - increase held lock count on a lock that is already held
* @lock: lock to increment
* @type: SIX_LOCK_read or SIX_LOCK_intent
*
* @lock must already be held, with a lock type that is greater than or equal to
* @type
*
* A corresponding six_unlock_type() call will be required for @lock to be fully
* unlocked.
*/
void six_lock_increment(struct six_lock *lock, enum six_lock_type type)
{
@ -809,6 +900,16 @@ void six_lock_increment(struct six_lock *lock, enum six_lock_type type)
}
EXPORT_SYMBOL_GPL(six_lock_increment);
/**
* six_lock_wakeup_all - wake up all waiters on @lock
* @lock: lock to wake up waiters for
*
* Wakeing up waiters will cause them to re-run should_sleep_fn, which may then
* abort the lock operation.
*
* This function is never needed in a bug-free program; it's only useful in
* debug code, e.g. to determine if a cycle detector is at fault.
*/
void six_lock_wakeup_all(struct six_lock *lock)
{
u64 state = atomic64_read(&lock->state);
@ -825,8 +926,11 @@ void six_lock_wakeup_all(struct six_lock *lock)
}
EXPORT_SYMBOL_GPL(six_lock_wakeup_all);
/*
* Returns lock held counts, for both read and intent
/**
* six_lock_counts - return held lock counts, for each lock type
* @lock: lock to return counters for
*
* Return: the number of times a lock is held for read, intent and write.
*/
struct six_lock_count six_lock_counts(struct six_lock *lock)
{
@ -843,15 +947,45 @@ struct six_lock_count six_lock_counts(struct six_lock *lock)
}
EXPORT_SYMBOL_GPL(six_lock_counts);
/**
* six_lock_readers_add - directly manipulate reader count of a lock
* @lock: lock to add/subtract readers for
* @nr: reader count to add/subtract
*
* When an upper layer is implementing lock reentrency, we may have both read
* and intent locks on the same lock.
*
* When we need to take a write lock, the read locks will cause self-deadlock,
* because six locks themselves do not track which read locks are held by the
* current thread and which are held by a different thread - it does no
* per-thread tracking of held locks.
*
* The upper layer that is tracking held locks may however, if trylock() has
* failed, count up its own read locks, subtract them, take the write lock, and
* then re-add them.
*
* As in any other situation when taking a write lock, @lock must be held for
* intent one (or more) times, so @lock will never be left unlocked.
*/
void six_lock_readers_add(struct six_lock *lock, int nr)
{
if (lock->readers)
if (lock->readers) {
this_cpu_add(*lock->readers, nr);
else /* reader count starts at bit 0 */
} else {
EBUG_ON((int) (atomic64_read(&lock->state) & SIX_STATE_READ_LOCK) + nr < 0);
/* reader count starts at bit 0 */
atomic64_add(nr, &lock->state);
}
}
EXPORT_SYMBOL_GPL(six_lock_readers_add);
/**
* six_lock_exit - release resources held by a lock prior to freeing
* @lock: lock to exit
*
* When a lock was initialized in percpu mode (SIX_OLCK_INIT_PCPU), this is
* required to free the percpu read counts.
*/
void six_lock_exit(struct six_lock *lock)
{
WARN_ON(lock->readers && pcpu_read_count(lock));

288
fs/bcachefs/six.h
View File

@ -3,59 +3,124 @@
#ifndef _LINUX_SIX_H
#define _LINUX_SIX_H
/*
* Shared/intent/exclusive locks: sleepable read/write locks, much like rw
* semaphores, except with a third intermediate state, intent. Basic operations
* are:
/**
* DOC: SIX locks overview
*
* six_lock_read(&foo->lock);
* six_unlock_read(&foo->lock);
* Shared/intent/exclusive locks: sleepable read/write locks, like rw semaphores
* but with an additional state: read/shared, intent, exclusive/write
*
* six_lock_intent(&foo->lock);
* six_unlock_intent(&foo->lock);
* The purpose of the intent state is to allow for greater concurrency on tree
* structures without deadlocking. In general, a read can't be upgraded to a
* write lock without deadlocking, so an operation that updates multiple nodes
* will have to take write locks for the full duration of the operation.
*
* six_lock_write(&foo->lock);
* six_unlock_write(&foo->lock);
* But by adding an intent state, which is exclusive with other intent locks but
* not with readers, we can take intent locks at thte start of the operation,
* and then take write locks only for the actual update to each individual
* nodes, without deadlocking.
*
* Intent locks block other intent locks, but do not block read locks, and you
* must have an intent lock held before taking a write lock, like so:
* Example usage:
* six_lock_read(&foo->lock);
* six_unlock_read(&foo->lock);
*
* six_lock_intent(&foo->lock);
* six_lock_write(&foo->lock);
* six_unlock_write(&foo->lock);
* six_unlock_intent(&foo->lock);
* An intent lock must be held before taking a write lock:
* six_lock_intent(&foo->lock);
* six_lock_write(&foo->lock);
* six_unlock_write(&foo->lock);
* six_unlock_intent(&foo->lock);
*
* Other operations:
*
* six_trylock_read()
* six_trylock_intent()
* six_trylock_write()
*
* six_lock_downgrade(): convert from intent to read
* six_lock_tryupgrade(): attempt to convert from read to intent
* six_lock_downgrade() convert from intent to read
* six_lock_tryupgrade() attempt to convert from read to intent, may fail
*
* Locks also embed a sequence number, which is incremented when the lock is
* locked or unlocked for write. The current sequence number can be grabbed
* while a lock is held from lock->state.seq; then, if you drop the lock you can
* use six_relock_(read|intent_write)(lock, seq) to attempt to retake the lock
* iff it hasn't been locked for write in the meantime.
* There are also interfaces that take the lock type as an enum:
*
* There are also operations that take the lock type as a parameter, where the
* type is one of SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write:
* six_lock_type(&foo->lock, SIX_LOCK_read);
* six_trylock_convert(&foo->lock, SIX_LOCK_read, SIX_LOCK_intent)
* six_lock_type(&foo->lock, SIX_LOCK_write);
* six_unlock_type(&foo->lock, SIX_LOCK_write);
* six_unlock_type(&foo->lock, SIX_LOCK_intent);
*
* six_lock_type(lock, type)
* six_unlock_type(lock, type)
* six_relock(lock, type, seq)
* six_trylock_type(lock, type)
* six_trylock_convert(lock, from, to)
* Lock sequence numbers - unlock(), relock():
*
* A lock may be held multiple times by the same thread (for read or intent,
* not write). However, the six locks code does _not_ implement the actual
* recursive checks itself though - rather, if your code (e.g. btree iterator
* code) knows that the current thread already has a lock held, and for the
* correct type, six_lock_increment() may be used to bump up the counter for
* that type - the only effect is that one more call to unlock will be required
* before the lock is unlocked.
* Locks embed sequences numbers, which are incremented on write lock/unlock.
* This allows locks to be dropped and the retaken iff the state they protect
* hasn't changed; this makes it much easier to avoid holding locks while e.g.
* doing IO or allocating memory.
*
* Example usage:
* six_lock_read(&foo->lock);
* u32 seq = six_lock_seq(&foo->lock);
* six_unlock_read(&foo->lock);
*
* some_operation_that_may_block();
*
* if (six_relock_read(&foo->lock, seq)) { ... }
*
* If the relock operation succeeds, it is as if the lock was never unlocked.
*
* Reentrancy:
*
* Six locks are not by themselves reentrent, but have counters for both the
* read and intent states that can be used to provide reentrency by an upper
* layer that tracks held locks. If a lock is known to already be held in the
* read or intent state, six_lock_increment() can be used to bump the "lock
* held in this state" counter, increasing the number of unlock calls that
* will be required to fully unlock it.
*
* Example usage:
* six_lock_read(&foo->lock);
* six_lock_increment(&foo->lock, SIX_LOCK_read);
* six_unlock_read(&foo->lock);
* six_unlock_read(&foo->lock);
* foo->lock is now fully unlocked.
*
* Since the intent state supercedes read, it's legal to increment the read
* counter when holding an intent lock, but not the reverse.
*
* A lock may only be held once for write: six_lock_increment(.., SIX_LOCK_write)
* is not legal.
*
* should_sleep_fn:
*
* There is a six_lock() variant that takes a function pointer that is called
* immediately prior to schedule() when blocking, and may return an error to
* abort.
*
* One possible use for this feature is when objects being locked are part of
* a cache and may reused, and lock ordering is based on a property of the
* object that will change when the object is reused - i.e. logical key order.
*
* If looking up an object in the cache may race with object reuse, and lock
* ordering is required to prevent deadlock, object reuse may change the
* correct lock order for that object and cause a deadlock. should_sleep_fn
* can be used to check if the object is still the object we want and avoid
* this deadlock.
*
* Wait list entry interface:
*
* There is a six_lock() variant, six_lock_waiter(), that takes a pointer to a
* wait list entry. By embedding six_lock_waiter into another object, and by
* traversing lock waitlists, it is then possible for an upper layer to
* implement full cycle detection for deadlock avoidance.
*
* should_sleep_fn should be used for invoking the cycle detector, walking the
* graph of held locks to check for a deadlock. The upper layer must track
* held locks for each thread, and each thread's held locks must be reachable
* from its six_lock_waiter object.
*
* six_lock_waiter() will add the wait object to the waitlist re-trying taking
* the lock, and before calling should_sleep_fn, and the wait object will not
* be removed from the waitlist until either the lock has been successfully
* acquired, or we aborted because should_sleep_fn returned an error.
*
* Also, six_lock_waiter contains a timestamp, and waiters on a waitlist will
* have timestamps in strictly ascending order - this is so the timestamp can
* be used as a cursor for lock graph traverse.
*/
#include <linux/lockdep.h>
@ -66,8 +131,6 @@
#include <linux/osq_lock.h>
#endif
#define SIX_LOCK_SEPARATE_LOCKFNS
enum six_lock_type {
SIX_LOCK_read,
SIX_LOCK_intent,
@ -108,6 +171,11 @@ enum six_lock_init_flags {
void __six_lock_init(struct six_lock *lock, const char *name,
struct lock_class_key *key, enum six_lock_init_flags flags);
/**
* six_lock_init - initialize a six lock
* @lock: lock to initialize
* @flags: optional flags, i.e. SIX_LOCK_INIT_PCPU
*/
#define six_lock_init(lock, flags) \
do { \
static struct lock_class_key __key; \
@ -115,73 +183,148 @@ do { \
__six_lock_init((lock), #lock, &__key, flags); \
} while (0)
/**
* six_lock_seq - obtain current lock sequence number
* @lock: six_lock to obtain sequence number for
*
* @lock should be held for read or intent, and not write
*
* By saving the lock sequence number, we can unlock @lock and then (typically
* after some blocking operation) attempt to relock it: the relock will succeed
* if the sequence number hasn't changed, meaning no write locks have been taken
* and state corresponding to what @lock protects is still valid.
*/
static inline u32 six_lock_seq(const struct six_lock *lock)
{
return atomic64_read(&lock->state) >> 32;
}
bool six_trylock_ip_type(struct six_lock *lock, enum six_lock_type type,
unsigned long ip);
bool six_trylock_ip(struct six_lock *lock, enum six_lock_type type, unsigned long ip);
/**
* six_trylock_type - attempt to take a six lock without blocking
* @lock: lock to take
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
*
* Return: true on success, false on failure.
*/
static inline bool six_trylock_type(struct six_lock *lock, enum six_lock_type type)
{
return six_trylock_ip_type(lock, type, _THIS_IP_);
return six_trylock_ip(lock, type, _THIS_IP_);
}
int six_lock_type_ip_waiter(struct six_lock *lock, enum six_lock_type type,
struct six_lock_waiter *wait,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip);
int six_lock_ip_waiter(struct six_lock *lock, enum six_lock_type type,
struct six_lock_waiter *wait,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip);
static inline int six_lock_type_waiter(struct six_lock *lock, enum six_lock_type type,
struct six_lock_waiter *wait,
six_lock_should_sleep_fn should_sleep_fn, void *p)
/**
* six_lock_waiter - take a lock, with full waitlist interface
* @lock: lock to take
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
* @wait: pointer to wait object, which will be added to lock's waitlist
* @should_sleep_fn: callback run after adding to waitlist, immediately prior
* to scheduling
* @p: passed through to @should_sleep_fn
*
* This is a convenience wrapper around six_lock_ip_waiter(), see that function
* for full documentation.
*
* Return: 0 on success, or the return code from @should_sleep_fn on failure.
*/
static inline int six_lock_waiter(struct six_lock *lock, enum six_lock_type type,
struct six_lock_waiter *wait,
six_lock_should_sleep_fn should_sleep_fn, void *p)
{
return six_lock_type_ip_waiter(lock, type, wait, should_sleep_fn, p, _THIS_IP_);
return six_lock_ip_waiter(lock, type, wait, should_sleep_fn, p, _THIS_IP_);
}
static inline int six_lock_ip_type(struct six_lock *lock, enum six_lock_type type,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip)
/**
* six_lock_ip - take a six lock lock
* @lock: lock to take
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
* @should_sleep_fn: callback run after adding to waitlist, immediately prior
* to scheduling
* @p: passed through to @should_sleep_fn
* @ip: ip parameter for lockdep/lockstat, i.e. _THIS_IP_
*
* Return: 0 on success, or the return code from @should_sleep_fn on failure.
*/
static inline int six_lock_ip(struct six_lock *lock, enum six_lock_type type,
six_lock_should_sleep_fn should_sleep_fn, void *p,
unsigned long ip)
{
struct six_lock_waiter wait;
return six_lock_type_ip_waiter(lock, type, &wait, should_sleep_fn, p, ip);
return six_lock_ip_waiter(lock, type, &wait, should_sleep_fn, p, ip);
}
/**
* six_lock_type - take a six lock lock
* @lock: lock to take
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
* @should_sleep_fn: callback run after adding to waitlist, immediately prior
* to scheduling
* @p: passed through to @should_sleep_fn
*
* Return: 0 on success, or the return code from @should_sleep_fn on failure.
*/
static inline int six_lock_type(struct six_lock *lock, enum six_lock_type type,
six_lock_should_sleep_fn should_sleep_fn, void *p)
{
struct six_lock_waiter wait;
return six_lock_type_ip_waiter(lock, type, &wait, should_sleep_fn, p, _THIS_IP_);
return six_lock_ip_waiter(lock, type, &wait, should_sleep_fn, p, _THIS_IP_);
}
bool six_relock_ip_type(struct six_lock *lock, enum six_lock_type type,
unsigned seq, unsigned long ip);
bool six_relock_ip(struct six_lock *lock, enum six_lock_type type,
unsigned seq, unsigned long ip);
/**
* six_relock_type - attempt to re-take a lock that was held previously
* @lock: lock to take
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
* @seq: lock sequence number obtained from six_lock_seq() while lock was
* held previously
*
* Return: true on success, false on failure.
*/
static inline bool six_relock_type(struct six_lock *lock, enum six_lock_type type,
unsigned seq)
{
return six_relock_ip_type(lock, type, seq, _THIS_IP_);
return six_relock_ip(lock, type, seq, _THIS_IP_);
}
void six_unlock_ip_type(struct six_lock *lock, enum six_lock_type type, unsigned long ip);
void six_unlock_ip(struct six_lock *lock, enum six_lock_type type, unsigned long ip);
/**
* six_unlock_type - drop a six lock
* @lock: lock to unlock
* @type: SIX_LOCK_read, SIX_LOCK_intent, or SIX_LOCK_write
*
* When a lock is held multiple times (because six_lock_incement()) was used),
* this decrements the 'lock held' counter by one.
*
* For example:
* six_lock_read(&foo->lock); read count 1
* six_lock_increment(&foo->lock, SIX_LOCK_read); read count 2
* six_lock_unlock(&foo->lock, SIX_LOCK_read); read count 1
* six_lock_unlock(&foo->lock, SIX_LOCK_read); read count 0
*/
static inline void six_unlock_type(struct six_lock *lock, enum six_lock_type type)
{
six_unlock_ip_type(lock, type, _THIS_IP_);
six_unlock_ip(lock, type, _THIS_IP_);
}
#define __SIX_LOCK(type) \
static inline bool six_trylock_ip_##type(struct six_lock *lock, unsigned long ip)\
{ \
return six_trylock_ip_type(lock, SIX_LOCK_##type, ip); \
return six_trylock_ip(lock, SIX_LOCK_##type, ip); \
} \
\
static inline bool six_trylock_##type(struct six_lock *lock) \
{ \
return six_trylock_ip_type(lock, SIX_LOCK_##type, _THIS_IP_); \
return six_trylock_ip(lock, SIX_LOCK_##type, _THIS_IP_); \
} \
\
static inline int six_lock_ip_waiter_##type(struct six_lock *lock, \
@ -189,24 +332,24 @@ static inline int six_lock_ip_waiter_##type(struct six_lock *lock, \
six_lock_should_sleep_fn should_sleep_fn, void *p,\
unsigned long ip) \
{ \
return six_lock_type_ip_waiter(lock, SIX_LOCK_##type, wait, should_sleep_fn, p, ip);\
return six_lock_ip_waiter(lock, SIX_LOCK_##type, wait, should_sleep_fn, p, ip);\
} \
\
static inline int six_lock_ip_##type(struct six_lock *lock, \
six_lock_should_sleep_fn should_sleep_fn, void *p, \
unsigned long ip) \
{ \
return six_lock_ip_type(lock, SIX_LOCK_##type, should_sleep_fn, p, ip);\
return six_lock_ip(lock, SIX_LOCK_##type, should_sleep_fn, p, ip);\
} \
\
static inline bool six_relock_ip_##type(struct six_lock *lock, u32 seq, unsigned long ip)\
{ \
return six_relock_ip_type(lock, SIX_LOCK_##type, seq, ip); \
return six_relock_ip(lock, SIX_LOCK_##type, seq, ip); \
} \
\
static inline bool six_relock_##type(struct six_lock *lock, u32 seq) \
{ \
return six_relock_ip_type(lock, SIX_LOCK_##type, seq, _THIS_IP_);\
return six_relock_ip(lock, SIX_LOCK_##type, seq, _THIS_IP_); \
} \
\
static inline int six_lock_##type(struct six_lock *lock, \
@ -215,21 +358,14 @@ static inline int six_lock_##type(struct six_lock *lock, \
return six_lock_ip_##type(lock, fn, p, _THIS_IP_); \
} \
\
static inline int six_lock_waiter_##type(struct six_lock *lock, \
struct six_lock_waiter *wait, \
six_lock_should_sleep_fn fn, void *p) \
{ \
return six_lock_ip_waiter_##type(lock, wait, fn, p, _THIS_IP_); \
} \
\
static inline void six_unlock_ip_##type(struct six_lock *lock, unsigned long ip) \
{ \
six_unlock_ip_type(lock, SIX_LOCK_##type, ip); \
six_unlock_ip(lock, SIX_LOCK_##type, ip); \
} \
\
static inline void six_unlock_##type(struct six_lock *lock) \
{ \
six_unlock_ip_type(lock, SIX_LOCK_##type, _THIS_IP_); \
six_unlock_ip(lock, SIX_LOCK_##type, _THIS_IP_); \
}
__SIX_LOCK(read)