-799716df00709f7480f575e8fd626915bafba006
+31c09369cd01b34fb8ba845fa09776576b03a1e2
#define __ATOMIC_SUB(v, p) uatomic_sub(p, v)
#define __ATOMIC_INC(p) uatomic_inc(p)
#define __ATOMIC_DEC(p) uatomic_dec(p)
+#define __ATOMIC_AND(v, p) uatomic_and(p, v)
+#define __ATOMIC_OR(v, p) uatomic_or(p, v)
#define xchg(p, v) uatomic_xchg(p, v)
#define xchg_acquire(p, v) uatomic_xchg(p, v)
#define __ATOMIC_SUB_RETURN(v, p) __atomic_sub_fetch(p, v, __ATOMIC_RELAXED)
#define __ATOMIC_SUB_RETURN_RELEASE(v, p) \
__atomic_sub_fetch(p, v, __ATOMIC_RELEASE)
+#define __ATOMIC_AND(p) __atomic_and_fetch(p, v, __ATOMIC_RELAXED)
+#define __ATOMIC_OR(p) __atomic_or_fetch(p, v, __ATOMIC_RELAXED)
#define xchg(p, v) __atomic_exchange_n(p, v, __ATOMIC_SEQ_CST)
#define xchg_acquire(p, v) __atomic_exchange_n(p, v, __ATOMIC_ACQUIRE)
return a_type##_add_unless(v, 1, 0); \
} \
\
+static inline void a_type##_and(i_type a, a_type##_t *v) \
+{ \
+ __ATOMIC_AND(a, v); \
+} \
+ \
+static inline void a_type##_or(i_type a, a_type##_t *v) \
+{ \
+ __ATOMIC_OR(a, v); \
+} \
+ \
static inline i_type a_type##_xchg(a_type##_t *v, i_type i) \
{ \
return xchg(&v->counter, i); \
#ifndef MEAN_AND_VARIANCE_H_
#define MEAN_AND_VARIANCE_H_
-#include <linux/kernel.h>
#include <linux/types.h>
+#include <linux/kernel.h>
#include <linux/limits.h>
#include <linux/math64.h>
+#include <stdlib.h>
#define SQRT_U64_MAX 4294967295ULL
-/**
- * abs - return absolute value of an argument
- * @x: the value. If it is unsigned type, it is converted to signed type first.
- * char is treated as if it was signed (regardless of whether it really is)
- * but the macro's return type is preserved as char.
- *
- * Return: an absolute value of x.
+/*
+ * u128_u: u128 user mode, because not all architectures support a real int128
+ * type
*/
-#define abs(x) __abs_choose_expr(x, long long, \
- __abs_choose_expr(x, long, \
- __abs_choose_expr(x, int, \
- __abs_choose_expr(x, short, \
- __abs_choose_expr(x, char, \
- __builtin_choose_expr( \
- __builtin_types_compatible_p(typeof(x), char), \
- (char)({ signed char __x = (x); __x<0?-__x:__x; }), \
- ((void)0)))))))
-#define __abs_choose_expr(x, type, other) __builtin_choose_expr( \
- __builtin_types_compatible_p(typeof(x), signed type) || \
- __builtin_types_compatible_p(typeof(x), unsigned type), \
- ({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
+#ifdef __SIZEOF_INT128__
-#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
-
-typedef unsigned __int128 u128;
+typedef struct {
+ unsigned __int128 v;
+} __aligned(16) u128_u;
-static inline u128 u64_to_u128(u64 a)
+static inline u128_u u64_to_u128(u64 a)
{
- return (u128)a;
+ return (u128_u) { .v = a };
}
-static inline u64 u128_to_u64(u128 a)
+static inline u64 u128_lo(u128_u a)
{
- return (u64)a;
+ return a.v;
}
-static inline u64 u128_shr64_to_u64(u128 a)
+static inline u64 u128_hi(u128_u a)
{
- return (u64)(a >> 64);
+ return a.v >> 64;
}
-static inline u128 u128_add(u128 a, u128 b)
+static inline u128_u u128_add(u128_u a, u128_u b)
{
- return a + b;
+ a.v += b.v;
+ return a;
}
-static inline u128 u128_sub(u128 a, u128 b)
+static inline u128_u u128_sub(u128_u a, u128_u b)
{
- return a - b;
+ a.v -= b.v;
+ return a;
}
-static inline u128 u128_shl(u128 i, s8 shift)
+static inline u128_u u128_shl(u128_u a, s8 shift)
{
- return i << shift;
+ a.v <<= shift;
+ return a;
}
-static inline u128 u128_shl64_add(u64 a, u64 b)
+static inline u128_u u128_square(u64 a)
{
- return ((u128)a << 64) + b;
-}
+ u128_u b = u64_to_u128(a);
-static inline u128 u128_square(u64 i)
-{
- return i*i;
+ b.v *= b.v;
+ return b;
}
#else
typedef struct {
u64 hi, lo;
-} u128;
+} __aligned(16) u128_u;
+
+/* conversions */
-static inline u128 u64_to_u128(u64 a)
+static inline u128_u u64_to_u128(u64 a)
{
- return (u128){ .lo = a };
+ return (u128_u) { .lo = a };
}
-static inline u64 u128_to_u64(u128 a)
+static inline u64 u128_lo(u128_u a)
{
return a.lo;
}
-static inline u64 u128_shr64_to_u64(u128 a)
+static inline u64 u128_hi(u128_u a)
{
return a.hi;
}
-static inline u128 u128_add(u128 a, u128 b)
+/* arithmetic */
+
+static inline u128_u u128_add(u128_u a, u128_u b)
{
- u128 c;
+ u128_u c;
c.lo = a.lo + b.lo;
c.hi = a.hi + b.hi + (c.lo < a.lo);
return c;
}
-static inline u128 u128_sub(u128 a, u128 b)
+static inline u128_u u128_sub(u128_u a, u128_u b)
{
- u128 c;
+ u128_u c;
c.lo = a.lo - b.lo;
c.hi = a.hi - b.hi - (c.lo > a.lo);
return c;
}
-static inline u128 u128_shl(u128 i, s8 shift)
+static inline u128_u u128_shl(u128_u i, s8 shift)
{
- u128 r;
+ u128_u r;
r.lo = i.lo << shift;
if (shift < 64)
return r;
}
-static inline u128 u128_shl64_add(u64 a, u64 b)
+static inline u128_u u128_square(u64 i)
{
- return u128_add(u128_shl(u64_to_u128(a), 64), u64_to_u128(b));
-}
-
-static inline u128 u128_square(u64 i)
-{
- u128 r;
- u64 h = i >> 32, l = i & (u64)U32_MAX;
+ u128_u r;
+ u64 h = i >> 32, l = i & U32_MAX;
r = u128_shl(u64_to_u128(h*h), 64);
r = u128_add(r, u128_shl(u64_to_u128(h*l), 32));
#endif
-static inline u128 u128_div(u128 n, u64 d)
+static inline u128_u u64s_to_u128(u64 hi, u64 lo)
{
- u128 r;
- u64 rem;
- u64 hi = u128_shr64_to_u64(n);
- u64 lo = u128_to_u64(n);
- u64 h = hi & ((u64)U32_MAX << 32);
- u64 l = (hi & (u64)U32_MAX) << 32;
+ u128_u c = u64_to_u128(hi);
- r = u128_shl(u64_to_u128(div64_u64_rem(h, d, &rem)), 64);
- r = u128_add(r, u128_shl(u64_to_u128(div64_u64_rem(l + (rem << 32), d, &rem)), 32));
- r = u128_add(r, u64_to_u128(div64_u64_rem(lo + (rem << 32), d, &rem)));
- return r;
+ c = u128_shl(c, 64);
+ c = u128_add(c, u64_to_u128(lo));
+ return c;
}
+u128_u u128_div(u128_u n, u64 d);
+
struct mean_and_variance {
- s64 n;
- s64 sum;
- u128 sum_squares;
+ s64 n;
+ s64 sum;
+ u128_u sum_squares;
};
/* expontentially weighted variant */
struct mean_and_variance_weighted {
- bool init;
- u8 w;
- s64 mean;
- u64 variance;
+ bool init;
+ u8 weight; /* base 2 logarithim */
+ s64 mean;
+ u64 variance;
};
-s64 fast_divpow2(s64 n, u8 d);
+/**
+ * fast_divpow2() - fast approximation for n / (1 << d)
+ * @n: numerator
+ * @d: the power of 2 denominator.
+ *
+ * note: this rounds towards 0.
+ */
+static inline s64 fast_divpow2(s64 n, u8 d)
+{
+ return (n + ((n < 0) ? ((1 << d) - 1) : 0)) >> d;
+}
+/**
+ * mean_and_variance_update() - update a mean_and_variance struct @s1 with a new sample @v1
+ * and return it.
+ * @s1: the mean_and_variance to update.
+ * @v1: the new sample.
+ *
+ * see linked pdf equation 12.
+ */
static inline struct mean_and_variance
-mean_and_variance_update_inlined(struct mean_and_variance s1, s64 v1)
-{
- struct mean_and_variance s2;
- u64 v2 = abs(v1);
-
- s2.n = s1.n + 1;
- s2.sum = s1.sum + v1;
- s2.sum_squares = u128_add(s1.sum_squares, u128_square(v2));
- return s2;
-}
-
-static inline struct mean_and_variance_weighted
-mean_and_variance_weighted_update_inlined(struct mean_and_variance_weighted s1, s64 x)
-{
- struct mean_and_variance_weighted s2;
- // previous weighted variance.
- u64 var_w0 = s1.variance;
- u8 w = s2.w = s1.w;
- // new value weighted.
- s64 x_w = x << w;
- s64 diff_w = x_w - s1.mean;
- s64 diff = fast_divpow2(diff_w, w);
- // new mean weighted.
- s64 u_w1 = s1.mean + diff;
-
- BUG_ON(w % 2 != 0);
-
- if (!s1.init) {
- s2.mean = x_w;
- s2.variance = 0;
- } else {
- s2.mean = u_w1;
- s2.variance = ((var_w0 << w) - var_w0 + ((diff_w * (x_w - u_w1)) >> w)) >> w;
- }
- s2.init = true;
-
- return s2;
+mean_and_variance_update(struct mean_and_variance s, s64 v)
+{
+ return (struct mean_and_variance) {
+ .n = s.n + 1,
+ .sum = s.sum + v,
+ .sum_squares = u128_add(s.sum_squares, u128_square(abs(v))),
+ };
}
-struct mean_and_variance mean_and_variance_update(struct mean_and_variance s1, s64 v1);
- s64 mean_and_variance_get_mean(struct mean_and_variance s);
- u64 mean_and_variance_get_variance(struct mean_and_variance s1);
- u32 mean_and_variance_get_stddev(struct mean_and_variance s);
+s64 mean_and_variance_get_mean(struct mean_and_variance s);
+u64 mean_and_variance_get_variance(struct mean_and_variance s1);
+u32 mean_and_variance_get_stddev(struct mean_and_variance s);
+
+void mean_and_variance_weighted_update(struct mean_and_variance_weighted *s, s64 v);
-struct mean_and_variance_weighted mean_and_variance_weighted_update(struct mean_and_variance_weighted s1, s64 v1);
- s64 mean_and_variance_weighted_get_mean(struct mean_and_variance_weighted s);
- u64 mean_and_variance_weighted_get_variance(struct mean_and_variance_weighted s);
- u32 mean_and_variance_weighted_get_stddev(struct mean_and_variance_weighted s);
+s64 mean_and_variance_weighted_get_mean(struct mean_and_variance_weighted s);
+u64 mean_and_variance_weighted_get_variance(struct mean_and_variance_weighted s);
+u32 mean_and_variance_weighted_get_stddev(struct mean_and_variance_weighted s);
#endif // MEAN_AND_VAIRANCE_H_
#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
- *
- * 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 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(lock, type)
- * six_unlock_type(lock, type)
- * six_relock(lock, type, seq)
- * six_trylock_type(lock, type)
- * six_trylock_convert(lock, from, to)
- *
- * 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.
+ * six_lock_downgrade() convert from intent to read
+ * six_lock_tryupgrade() attempt to convert from read to intent, may fail
+ *
+ * There are also interfaces that take the lock type as an enum:
+ *
+ * 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);
+ *
+ * Lock sequence numbers - unlock(), relock():
+ *
+ * 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>
#include <linux/sched.h>
#include <linux/types.h>
-#define SIX_LOCK_SEPARATE_LOCKFNS
-
-union six_lock_state {
- struct {
- atomic64_t counter;
- };
-
- struct {
- u64 v;
- };
-
- struct {
- /* for waitlist_bitnr() */
- unsigned long l;
- };
-
- struct {
- unsigned read_lock:26;
- unsigned write_locking:1;
- unsigned intent_lock:1;
- unsigned nospin:1;
- unsigned waiters:3;
- /*
- * seq works much like in seqlocks: it's incremented every time
- * we lock and unlock for write.
- *
- * If it's odd write lock is held, even unlocked.
- *
- * Thus readers can unlock, and then lock again later iff it
- * hasn't been modified in the meantime.
- */
- u32 seq;
- };
-};
-
enum six_lock_type {
SIX_LOCK_read,
SIX_LOCK_intent,
};
struct six_lock {
- union six_lock_state state;
+ atomic_t state;
+ u32 seq;
unsigned intent_lock_recurse;
struct task_struct *owner;
unsigned __percpu *readers;
typedef int (*six_lock_should_sleep_fn)(struct six_lock *lock, void *);
-static __always_inline void __six_lock_init(struct six_lock *lock,
- const char *name,
- struct lock_class_key *key)
-{
- atomic64_set(&lock->state.counter, 0);
- raw_spin_lock_init(&lock->wait_lock);
- INIT_LIST_HEAD(&lock->wait_list);
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- debug_check_no_locks_freed((void *) lock, sizeof(*lock));
- lockdep_init_map(&lock->dep_map, name, key, 0);
-#endif
-}
+void six_lock_exit(struct six_lock *lock);
+
+enum six_lock_init_flags {
+ SIX_LOCK_INIT_PCPU = 1U << 0,
+};
-#define six_lock_init(lock) \
+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; \
\
- __six_lock_init((lock), #lock, &__key); \
+ __six_lock_init((lock), #lock, &__key, flags); \
} while (0)
-#define __SIX_VAL(field, _v) (((union six_lock_state) { .field = _v }).v)
+/**
+ * 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 lock->seq;
+}
+
+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(lock, type, _THIS_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);
+
+/**
+ * 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_ip_waiter(lock, type, wait, should_sleep_fn, p, _THIS_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_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_ip_waiter(lock, type, &wait, should_sleep_fn, p, _THIS_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(lock, type, seq, _THIS_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(lock, type, _THIS_IP_);
+}
#define __SIX_LOCK(type) \
-bool six_trylock_ip_##type(struct six_lock *, unsigned long); \
-bool six_relock_ip_##type(struct six_lock *, u32, unsigned long); \
-int six_lock_ip_##type(struct six_lock *, six_lock_should_sleep_fn, \
- void *, unsigned long); \
-int six_lock_ip_waiter_##type(struct six_lock *, struct six_lock_waiter *,\
- six_lock_should_sleep_fn, void *, unsigned long);\
-void six_unlock_ip_##type(struct six_lock *, unsigned long); \
+static inline bool six_trylock_ip_##type(struct six_lock *lock, unsigned long 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, _THIS_IP_); \
+ return six_trylock_ip(lock, SIX_LOCK_##type, _THIS_IP_); \
+} \
+ \
+static inline int six_lock_ip_waiter_##type(struct six_lock *lock, \
+ struct six_lock_waiter *wait, \
+ six_lock_should_sleep_fn should_sleep_fn, void *p,\
+ unsigned long 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(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(lock, SIX_LOCK_##type, seq, ip); \
} \
+ \
static inline bool six_relock_##type(struct six_lock *lock, u32 seq) \
{ \
- return six_relock_ip_##type(lock, seq, _THIS_IP_); \
+ return six_relock_ip(lock, SIX_LOCK_##type, seq, _THIS_IP_); \
} \
+ \
static inline int six_lock_##type(struct six_lock *lock, \
six_lock_should_sleep_fn fn, void *p)\
{ \
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) \
+ \
+static inline void six_unlock_ip_##type(struct six_lock *lock, unsigned long ip) \
{ \
- return six_lock_ip_waiter_##type(lock, wait, fn, p, _THIS_IP_); \
+ six_unlock_ip(lock, SIX_LOCK_##type, ip); \
} \
+ \
static inline void six_unlock_##type(struct six_lock *lock) \
{ \
- return six_unlock_ip_##type(lock, _THIS_IP_); \
+ six_unlock_ip(lock, SIX_LOCK_##type, _THIS_IP_); \
}
__SIX_LOCK(read)
__SIX_LOCK(write)
#undef __SIX_LOCK
-#define SIX_LOCK_DISPATCH(type, fn, ...) \
- switch (type) { \
- case SIX_LOCK_read: \
- return fn##_read(__VA_ARGS__); \
- case SIX_LOCK_intent: \
- return fn##_intent(__VA_ARGS__); \
- case SIX_LOCK_write: \
- return fn##_write(__VA_ARGS__); \
- default: \
- BUG(); \
- }
-
-static inline bool six_trylock_type(struct six_lock *lock, enum six_lock_type type)
-{
- SIX_LOCK_DISPATCH(type, six_trylock, lock);
-}
-
-static inline bool six_relock_type(struct six_lock *lock, enum six_lock_type type,
- unsigned seq)
-{
- SIX_LOCK_DISPATCH(type, six_relock, lock, seq);
-}
-
-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)
-{
- SIX_LOCK_DISPATCH(type, six_lock, lock, should_sleep_fn, p);
-}
-
-static inline 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_DISPATCH(type, six_lock_ip_waiter, lock, wait, should_sleep_fn, p, 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_DISPATCH(type, six_lock_waiter, lock, wait, should_sleep_fn, p);
-}
-
-static inline void six_unlock_type(struct six_lock *lock, enum six_lock_type type)
-{
- SIX_LOCK_DISPATCH(type, six_unlock, lock);
-}
-
void six_lock_downgrade(struct six_lock *);
bool six_lock_tryupgrade(struct six_lock *);
bool six_trylock_convert(struct six_lock *, enum six_lock_type,
void six_lock_wakeup_all(struct six_lock *);
-void six_lock_pcpu_free(struct six_lock *);
-void six_lock_pcpu_alloc(struct six_lock *);
-
struct six_lock_count {
unsigned n[3];
};
struct six_lock_count six_lock_counts(struct six_lock *);
+void six_lock_readers_add(struct six_lock *, int);
#endif /* _LINUX_SIX_H */
struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(k);
int rw = flags & WRITE;
- if (alloc_v4_u64s(a.v) != bkey_val_u64s(k.k)) {
- prt_printf(err, "bad val size (%lu != %u)",
- bkey_val_u64s(k.k), alloc_v4_u64s(a.v));
+ if (alloc_v4_u64s(a.v) > bkey_val_u64s(k.k)) {
+ prt_printf(err, "bad val size (%u > %lu)",
+ alloc_v4_u64s(a.v), bkey_val_u64s(k.k));
return -BCH_ERR_invalid_bkey;
}
return 0;
}
-#ifdef CONFIG_X86_64
+#ifdef HAVE_BCACHEFS_COMPILED_UNPACK
#define I(_x) (*(out)++ = (_x))
#define I1(i0) I(i0)
#include "util.h"
#include "vstructs.h"
+#if 0
+
+/*
+ * compiled unpack functions are disabled, pending a new interface for
+ * dynamically allocating executable memory:
+ */
+
#ifdef CONFIG_X86_64
#define HAVE_BCACHEFS_COMPILED_UNPACK 1
#endif
+#endif
void bch2_bkey_packed_to_binary_text(struct printbuf *,
const struct bkey_format *,
EBUG_ON(btree_node_write_in_flight(b));
+ clear_btree_node_just_written(b);
+
kvpfree(b->data, btree_bytes(c));
b->data = NULL;
#ifdef __KERNEL__
- vfree(b->aux_data);
+ kvfree(b->aux_data);
#else
munmap(b->aux_data, btree_aux_data_bytes(b));
#endif
if (!b->data)
return -BCH_ERR_ENOMEM_btree_node_mem_alloc;
#ifdef __KERNEL__
- b->aux_data = vmalloc_exec(btree_aux_data_bytes(b), gfp);
+ b->aux_data = kvmalloc(btree_aux_data_bytes(b), gfp);
#else
b->aux_data = mmap(NULL, btree_aux_data_bytes(b),
PROT_READ|PROT_WRITE|PROT_EXEC,
return NULL;
bkey_btree_ptr_init(&b->key);
- bch2_btree_lock_init(&b->c);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
lockdep_set_no_check_recursion(&b->c.lock.dep_map);
#endif
return NULL;
}
+ bch2_btree_lock_init(&b->c, 0);
+
bc->used++;
list_add(&b->list, &bc->freeable);
return b;
while (!list_empty(&bc->freed_nonpcpu)) {
b = list_first_entry(&bc->freed_nonpcpu, struct btree, list);
list_del(&b->list);
- six_lock_pcpu_free(&b->c.lock);
+ six_lock_exit(&b->c.lock);
kfree(b);
}
mutex_lock(&bc->lock);
}
- if (pcpu_read_locks)
- six_lock_pcpu_alloc(&b->c.lock);
+ bch2_btree_lock_init(&b->c, pcpu_read_locks ? SIX_LOCK_INIT_PCPU : 0);
BUG_ON(!six_trylock_intent(&b->c.lock));
BUG_ON(!six_trylock_write(&b->c.lock));
/* Try to cannibalize another cached btree node: */
if (bc->alloc_lock == current) {
b2 = btree_node_cannibalize(c);
+ clear_btree_node_just_written(b2);
bch2_btree_node_hash_remove(bc, b2);
if (b) {
set_btree_node_read_in_flight(b);
six_unlock_write(&b->c.lock);
- seq = b->c.lock.state.seq;
+ seq = six_lock_seq(&b->c.lock);
six_unlock_intent(&b->c.lock);
/* Unlock before doing IO: */
}
if (unlikely(btree_node_read_in_flight(b))) {
- u32 seq = b->c.lock.state.seq;
+ u32 seq = six_lock_seq(&b->c.lock);
six_unlock_type(&b->c.lock, lock_type);
bch2_trans_unlock(trans);
}
if (unlikely(btree_node_read_in_flight(b))) {
- u32 seq = b->c.lock.state.seq;
+ u32 seq = six_lock_seq(&b->c.lock);
six_unlock_type(&b->c.lock, lock_type);
bch2_trans_unlock(trans);
struct btree_node_entry *bne;
bool reinit_iter = false;
- EBUG_ON(!(b->c.lock.state.seq & 1));
+ EBUG_ON(!six_lock_counts(&b->c.lock).n[SIX_LOCK_write]);
BUG_ON(bset_written(b, bset(b, &b->set[1])));
BUG_ON(btree_node_just_written(b));
BUG_ON(path->cached);
EBUG_ON(!btree_path_pos_in_node(path, b));
- EBUG_ON(b->c.lock.state.seq & 1);
- path->l[b->c.level].lock_seq = b->c.lock.state.seq;
+ path->l[b->c.level].lock_seq = six_lock_seq(&b->c.lock);
path->l[b->c.level].b = b;
__btree_path_level_init(path, b->c.level);
}
static inline bool btree_node_lock_seq_matches(const struct btree_path *path,
const struct btree *b, unsigned level)
{
- /*
- * We don't compare the low bits of the lock sequence numbers because
- * @path might have taken a write lock on @b, and we don't want to skip
- * the linked path if the sequence numbers were equal before taking that
- * write lock. The lock sequence number is incremented by taking and
- * releasing write locks and is even when unlocked:
- */
- return path->l[level].lock_seq >> 1 == b->c.lock.state.seq >> 1;
+ return path->l[level].lock_seq == six_lock_seq(&b->c.lock);
}
static inline struct btree *btree_node_parent(struct btree_path *path,
}
path->l[0].b = (void *) ck;
- path->l[0].lock_seq = ck->c.lock.state.seq;
+ path->l[0].lock_seq = six_lock_seq(&ck->c.lock);
mark_btree_node_locked(trans, path, 0, SIX_LOCK_intent);
ret = bch2_btree_node_lock_write(trans, path, &ck->c);
return NULL;
init:
INIT_LIST_HEAD(&ck->list);
- bch2_btree_lock_init(&ck->c);
- if (pcpu_readers)
- six_lock_pcpu_alloc(&ck->c.lock);
+ bch2_btree_lock_init(&ck->c, pcpu_readers ? SIX_LOCK_INIT_PCPU : 0);
ck->c.cached = true;
BUG_ON(!six_trylock_intent(&ck->c.lock));
}
mark_btree_node_locked(trans, path, 0, SIX_LOCK_intent);
- } else {
- if (path->btree_id == BTREE_ID_subvolumes)
- six_lock_pcpu_alloc(&ck->c.lock);
}
ck->c.level = 0;
mark_btree_node_locked(trans, path, 0, lock_want);
}
- path->l[0].lock_seq = ck->c.lock.state.seq;
+ path->l[0].lock_seq = six_lock_seq(&ck->c.lock);
path->l[0].b = (void *) ck;
fill:
path->uptodate = BTREE_ITER_UPTODATE;
mark_btree_node_locked(trans, path, 0, lock_want);
}
- path->l[0].lock_seq = ck->c.lock.state.seq;
+ path->l[0].lock_seq = six_lock_seq(&ck->c.lock);
path->l[0].b = (void *) ck;
fill:
if (!ck->valid)
break;
list_del(&ck->list);
- six_lock_pcpu_free(&ck->c.lock);
+ six_lock_exit(&ck->c.lock);
kmem_cache_free(bch2_key_cache, ck);
atomic_long_dec(&bc->nr_freed);
scanned++;
break;
list_del(&ck->list);
- six_lock_pcpu_free(&ck->c.lock);
+ six_lock_exit(&ck->c.lock);
kmem_cache_free(bch2_key_cache, ck);
atomic_long_dec(&bc->nr_freed);
scanned++;
list_del(&ck->list);
kfree(ck->k);
- six_lock_pcpu_free(&ck->c.lock);
+ six_lock_exit(&ck->c.lock);
kmem_cache_free(bch2_key_cache, ck);
}
static struct lock_class_key bch2_btree_node_lock_key;
-void bch2_btree_lock_init(struct btree_bkey_cached_common *b)
+void bch2_btree_lock_init(struct btree_bkey_cached_common *b,
+ enum six_lock_init_flags flags)
{
- __six_lock_init(&b->lock, "b->c.lock", &bch2_btree_node_lock_key);
+ __six_lock_init(&b->lock, "b->c.lock", &bch2_btree_node_lock_key, flags);
}
#ifdef CONFIG_LOCKDEP
/* Btree node locking: */
-static inline void six_lock_readers_add(struct six_lock *lock, int nr)
-{
- if (lock->readers)
- this_cpu_add(*lock->readers, nr);
- else if (nr > 0)
- atomic64_add(__SIX_VAL(read_lock, nr), &lock->state.counter);
- else
- atomic64_sub(__SIX_VAL(read_lock, -nr), &lock->state.counter);
-}
-
struct six_lock_count bch2_btree_node_lock_counts(struct btree_trans *trans,
struct btree_path *skip,
struct btree_bkey_cached_common *b,
#include "btree_iter.h"
-void bch2_btree_lock_init(struct btree_bkey_cached_common *);
+void bch2_btree_lock_init(struct btree_bkey_cached_common *, enum six_lock_init_flags);
#ifdef CONFIG_LOCKDEP
void bch2_assert_btree_nodes_not_locked(void);
struct btree_path *linked;
EBUG_ON(path->l[b->c.level].b != b);
- EBUG_ON(path->l[b->c.level].lock_seq + 1 != b->c.lock.state.seq);
+ EBUG_ON(path->l[b->c.level].lock_seq != six_lock_seq(&b->c.lock));
EBUG_ON(btree_node_locked_type(path, b->c.level) != SIX_LOCK_write);
mark_btree_node_locked_noreset(path, b->c.level, SIX_LOCK_intent);
trans_for_each_path_with_node(trans, b, linked)
- linked->l[b->c.level].lock_seq += 2;
+ linked->l[b->c.level].lock_seq++;
six_unlock_write(&b->c.lock);
}
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;
bool lock_may_not_fail)
{
EBUG_ON(&path->l[b->level].b->c != b);
- EBUG_ON(path->l[b->level].lock_seq != b->lock.state.seq);
+ EBUG_ON(path->l[b->level].lock_seq != six_lock_seq(&b->lock));
EBUG_ON(!btree_node_intent_locked(path, b->level));
/*
bch2_trans_unlock(&trans);
btree_node_lock_nopath_nofail(&trans, &b->c, SIX_LOCK_intent);
mark_btree_node_locked(&trans, path, b->c.level, SIX_LOCK_intent);
- path->l[b->c.level].lock_seq = b->c.lock.state.seq;
+ path->l[b->c.level].lock_seq = six_lock_seq(&b->c.lock);
path->l[b->c.level].b = b;
bch2_btree_node_lock_write_nofail(&trans, path, &b->c);
struct bch_fs_usage_online *bch2_fs_usage_read(struct bch_fs *c)
{
struct bch_fs_usage_online *ret;
- unsigned seq, i, v, u64s = fs_usage_u64s(c) + 1;
+ unsigned nr_replicas = READ_ONCE(c->replicas.nr);
+ unsigned seq, i;
retry:
- ret = kmalloc(u64s * sizeof(u64), GFP_NOFS);
+ ret = kmalloc(__fs_usage_online_u64s(nr_replicas) * sizeof(u64), GFP_NOFS);
if (unlikely(!ret))
return NULL;
percpu_down_read(&c->mark_lock);
- v = fs_usage_u64s(c) + 1;
- if (unlikely(u64s != v)) {
- u64s = v;
+ if (nr_replicas != c->replicas.nr) {
+ nr_replicas = c->replicas.nr;
percpu_up_read(&c->mark_lock);
kfree(ret);
goto retry;
do {
seq = read_seqcount_begin(&c->usage_lock);
- unsafe_memcpy(&ret->u, c->usage_base, u64s * sizeof(u64),
+ unsafe_memcpy(&ret->u, c->usage_base,
+ __fs_usage_u64s(nr_replicas) * sizeof(u64),
"embedded variable length struct");
for (i = 0; i < ARRAY_SIZE(c->usage); i++)
- acc_u64s_percpu((u64 *) &ret->u, (u64 __percpu *) c->usage[i], u64s);
+ acc_u64s_percpu((u64 *) &ret->u, (u64 __percpu *) c->usage[i],
+ __fs_usage_u64s(nr_replicas));
} while (read_seqcount_retry(&c->usage_lock, seq));
return ret;
/* Filesystem usage: */
+static inline unsigned __fs_usage_u64s(unsigned nr_replicas)
+{
+ return sizeof(struct bch_fs_usage) / sizeof(u64) + nr_replicas;
+}
+
static inline unsigned fs_usage_u64s(struct bch_fs *c)
{
- return sizeof(struct bch_fs_usage) / sizeof(u64) +
- READ_ONCE(c->replicas.nr);
+ return __fs_usage_u64s(READ_ONCE(c->replicas.nr));
+}
+
+static inline unsigned __fs_usage_online_u64s(unsigned nr_replicas)
+{
+ return sizeof(struct bch_fs_usage_online) / sizeof(u64) + nr_replicas;
+}
+
+static inline unsigned fs_usage_online_u64s(struct bch_fs *c)
+{
+ return __fs_usage_online_u64s(READ_ONCE(c->replicas.nr));
}
static inline unsigned dev_usage_u64s(void)
else
scnprintf(__entry->node, sizeof(__entry->node), "%px", b);
__entry->iter_lock_seq = path->l[level].lock_seq;
- __entry->node_lock_seq = is_btree_node(path, level) ? path->l[level].b->c.lock.state.seq : 0;
+ __entry->node_lock_seq = is_btree_node(path, level)
+ ? six_lock_seq(&path->l[level].b->c.lock)
+ : 0;
),
TP_printk("%s %pS btree %s pos %llu:%llu:%u level %u node %s iter seq %u lock seq %u",
__entry->read_count = c.n[SIX_LOCK_read];
__entry->intent_count = c.n[SIX_LOCK_read];
__entry->iter_lock_seq = path->l[level].lock_seq;
- __entry->node_lock_seq = is_btree_node(path, level) ? path->l[level].b->c.lock.state.seq : 0;
+ __entry->node_lock_seq = is_btree_node(path, level)
+ ? six_lock_seq(&path->l[level].b->c.lock)
+ : 0;
),
TP_printk("%s %pS btree %s pos %llu:%llu:%u level %u locked %u held %u:%u lock count %u:%u iter seq %u lock seq %u",
if (time_after64(end, start)) {
duration = end - start;
- stats->duration_stats = mean_and_variance_update_inlined(stats->duration_stats,
- duration);
- stats->duration_stats_weighted = mean_and_variance_weighted_update(
- stats->duration_stats_weighted,
- duration);
+ stats->duration_stats = mean_and_variance_update(stats->duration_stats, duration);
+ mean_and_variance_weighted_update(&stats->duration_stats_weighted, duration);
stats->max_duration = max(stats->max_duration, duration);
stats->min_duration = min(stats->min_duration, duration);
bch2_quantiles_update(&stats->quantiles, duration);
if (time_after64(end, stats->last_event)) {
freq = end - stats->last_event;
- stats->freq_stats = mean_and_variance_update_inlined(stats->freq_stats, freq);
- stats->freq_stats_weighted = mean_and_variance_weighted_update(
- stats->freq_stats_weighted,
- freq);
+ stats->freq_stats = mean_and_variance_update(stats->freq_stats, freq);
+ mean_and_variance_weighted_update(&stats->freq_stats_weighted, freq);
stats->max_freq = max(stats->max_freq, freq);
stats->min_freq = min(stats->min_freq, freq);
stats->last_event = end;
void bch2_time_stats_init(struct bch2_time_stats *stats)
{
memset(stats, 0, sizeof(*stats));
- stats->duration_stats_weighted.w = 8;
- stats->freq_stats_weighted.w = 8;
+ stats->duration_stats_weighted.weight = 8;
+ stats->freq_stats_weighted.weight = 8;
stats->min_duration = U64_MAX;
stats->min_freq = U64_MAX;
spin_lock_init(&stats->lock);
#include <linux/mean_and_variance.h>
#include <linux/module.h>
-/**
- * fast_divpow2() - fast approximation for n / (1 << d)
- * @n: numerator
- * @d: the power of 2 denominator.
- *
- * note: this rounds towards 0.
- */
-s64 fast_divpow2(s64 n, u8 d)
+u128_u u128_div(u128_u n, u64 d)
{
- return (n + ((n < 0) ? ((1 << d) - 1) : 0)) >> d;
-}
+ u128_u r;
+ u64 rem;
+ u64 hi = u128_hi(n);
+ u64 lo = u128_lo(n);
+ u64 h = hi & ((u64) U32_MAX << 32);
+ u64 l = (hi & (u64) U32_MAX) << 32;
-/**
- * mean_and_variance_update() - update a mean_and_variance struct @s1 with a new sample @v1
- * and return it.
- * @s1: the mean_and_variance to update.
- * @v1: the new sample.
- *
- * see linked pdf equation 12.
- */
-struct mean_and_variance mean_and_variance_update(struct mean_and_variance s1, s64 v1)
-{
- return mean_and_variance_update_inlined(s1, v1);
+ r = u128_shl(u64_to_u128(div64_u64_rem(h, d, &rem)), 64);
+ r = u128_add(r, u128_shl(u64_to_u128(div64_u64_rem(l + (rem << 32), d, &rem)), 32));
+ r = u128_add(r, u64_to_u128(div64_u64_rem(lo + (rem << 32), d, &rem)));
+ return r;
}
-EXPORT_SYMBOL_GPL(mean_and_variance_update);
+EXPORT_SYMBOL_GPL(u128_div);
/**
* mean_and_variance_get_mean() - get mean from @s
*/
s64 mean_and_variance_get_mean(struct mean_and_variance s)
{
- return div64_u64(s.sum, s.n);
+ return s.n ? div64_u64(s.sum, s.n) : 0;
}
EXPORT_SYMBOL_GPL(mean_and_variance_get_mean);
*/
u64 mean_and_variance_get_variance(struct mean_and_variance s1)
{
- u128 s2 = u128_div(s1.sum_squares, s1.n);
- u64 s3 = abs(mean_and_variance_get_mean(s1));
+ if (s1.n) {
+ u128_u s2 = u128_div(s1.sum_squares, s1.n);
+ u64 s3 = abs(mean_and_variance_get_mean(s1));
- return u128_to_u64(u128_sub(s2, u128_square(s3)));
+ return u128_lo(u128_sub(s2, u128_square(s3)));
+ } else {
+ return 0;
+ }
}
EXPORT_SYMBOL_GPL(mean_and_variance_get_variance);
* see linked pdf: function derived from equations 140-143 where alpha = 2^w.
* values are stored bitshifted for performance and added precision.
*/
-struct mean_and_variance_weighted mean_and_variance_weighted_update(struct mean_and_variance_weighted s1,
- s64 x)
+void mean_and_variance_weighted_update(struct mean_and_variance_weighted *s, s64 x)
{
- return mean_and_variance_weighted_update_inlined(s1, x);
+ // previous weighted variance.
+ u8 w = s->weight;
+ u64 var_w0 = s->variance;
+ // new value weighted.
+ s64 x_w = x << w;
+ s64 diff_w = x_w - s->mean;
+ s64 diff = fast_divpow2(diff_w, w);
+ // new mean weighted.
+ s64 u_w1 = s->mean + diff;
+
+ if (!s->init) {
+ s->mean = x_w;
+ s->variance = 0;
+ } else {
+ s->mean = u_w1;
+ s->variance = ((var_w0 << w) - var_w0 + ((diff_w * (x_w - u_w1)) >> w)) >> w;
+ }
+ s->init = true;
}
EXPORT_SYMBOL_GPL(mean_and_variance_weighted_update);
*/
s64 mean_and_variance_weighted_get_mean(struct mean_and_variance_weighted s)
{
- return fast_divpow2(s.mean, s.w);
+ return fast_divpow2(s.mean, s.weight);
}
EXPORT_SYMBOL_GPL(mean_and_variance_weighted_get_mean);
u64 mean_and_variance_weighted_get_variance(struct mean_and_variance_weighted s)
{
// always positive don't need fast divpow2
- return s.variance >> s.w;
+ return s.variance >> s.weight;
}
EXPORT_SYMBOL_GPL(mean_and_variance_weighted_get_variance);
#include <trace/events/lock.h>
#ifdef DEBUG
-#define EBUG_ON(cond) BUG_ON(cond)
+#define EBUG_ON(cond) BUG_ON(cond)
#else
-#define EBUG_ON(cond) do {} while (0)
+#define EBUG_ON(cond) do {} while (0)
#endif
#define six_acquire(l, t, r, ip) lock_acquire(l, 0, t, r, 1, NULL, ip)
static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type);
+#define SIX_LOCK_HELD_read_OFFSET 0
+#define SIX_LOCK_HELD_read ~(~0U << 26)
+#define SIX_LOCK_HELD_intent (1U << 26)
+#define SIX_LOCK_HELD_write (1U << 27)
+#define SIX_LOCK_WAITING_read (1U << (28 + SIX_LOCK_read))
+#define SIX_LOCK_WAITING_intent (1U << (28 + SIX_LOCK_intent))
+#define SIX_LOCK_WAITING_write (1U << (28 + SIX_LOCK_write))
+#define SIX_LOCK_NOSPIN (1U << 31)
+
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;
-
- /* Value we add to the lock in order to release the lock: */
- u64 unlock_val;
+ 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;
};
-#define __SIX_LOCK_HELD_read __SIX_VAL(read_lock, ~0)
-#define __SIX_LOCK_HELD_intent __SIX_VAL(intent_lock, ~0)
-#define __SIX_LOCK_HELD_write __SIX_VAL(seq, 1)
-
#define LOCK_VALS { \
[SIX_LOCK_read] = { \
- .lock_val = __SIX_VAL(read_lock, 1), \
- .lock_fail = __SIX_LOCK_HELD_write + __SIX_VAL(write_locking, 1),\
- .unlock_val = -__SIX_VAL(read_lock, 1), \
- .held_mask = __SIX_LOCK_HELD_read, \
+ .lock_val = 1U << SIX_LOCK_HELD_read_OFFSET, \
+ .lock_fail = SIX_LOCK_HELD_write, \
+ .held_mask = SIX_LOCK_HELD_read, \
.unlock_wakeup = SIX_LOCK_write, \
}, \
[SIX_LOCK_intent] = { \
- .lock_val = __SIX_VAL(intent_lock, 1), \
- .lock_fail = __SIX_LOCK_HELD_intent, \
- .unlock_val = -__SIX_VAL(intent_lock, 1), \
- .held_mask = __SIX_LOCK_HELD_intent, \
+ .lock_val = SIX_LOCK_HELD_intent, \
+ .lock_fail = SIX_LOCK_HELD_intent, \
+ .held_mask = SIX_LOCK_HELD_intent, \
.unlock_wakeup = SIX_LOCK_intent, \
}, \
[SIX_LOCK_write] = { \
- .lock_val = __SIX_VAL(seq, 1), \
- .lock_fail = __SIX_LOCK_HELD_read, \
- .unlock_val = __SIX_VAL(seq, 1), \
- .held_mask = __SIX_LOCK_HELD_write, \
+ .lock_val = SIX_LOCK_HELD_write, \
+ .lock_fail = SIX_LOCK_HELD_read, \
+ .held_mask = SIX_LOCK_HELD_write, \
.unlock_wakeup = SIX_LOCK_read, \
}, \
}
+static inline void six_set_bitmask(struct six_lock *lock, u32 mask)
+{
+ if ((atomic_read(&lock->state) & mask) != mask)
+ atomic_or(mask, &lock->state);
+}
+
+static inline void six_clear_bitmask(struct six_lock *lock, u32 mask)
+{
+ 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,
- union six_lock_state old,
- struct task_struct *owner)
+ u32 old, struct task_struct *owner)
{
if (type != SIX_LOCK_intent)
return;
- if (!old.intent_lock) {
+ if (!(old & SIX_LOCK_HELD_intent)) {
EBUG_ON(lock->owner);
lock->owner = owner;
} else {
return read_count;
}
-/* This is probably up there with the more evil things I've done */
-#define waitlist_bitnr(id) ilog2((((union six_lock_state) { .waiters = 1 << (id) }).l))
-
-static int __do_six_trylock_type(struct six_lock *lock,
- enum six_lock_type type,
- struct task_struct *task,
- bool try)
+/*
+ * __do_six_trylock() - main trylock routine
+ *
+ * Returns 1 on success, 0 on failure
+ *
+ * In percpu reader mode, a failed trylock may cause a spurious trylock failure
+ * for anoter thread taking the competing lock type, and we may havve to do a
+ * wakeup: when a wakeup is required, we return -1 - wakeup_type.
+ */
+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;
- union six_lock_state old, new;
int ret;
- u64 v;
+ u32 old, new, v;
EBUG_ON(type == SIX_LOCK_write && lock->owner != task);
- EBUG_ON(type == SIX_LOCK_write && (lock->state.seq & 1));
- EBUG_ON(type == SIX_LOCK_write && (try != !(lock->state.write_locking)));
+ EBUG_ON(type == SIX_LOCK_write &&
+ (try != !(atomic_read(&lock->state) & SIX_LOCK_HELD_write)));
/*
* Percpu reader mode:
* the lock, then issues a full memory barrier, then reads from the
* other thread's variable to check if the other thread thinks it has
* the lock. If we raced, we backoff and retry/sleep.
+ *
+ * Failure to take the lock may cause a spurious trylock failure in
+ * another thread, because we temporarily set the lock to indicate that
+ * we held it. This would be a problem for a thread in six_lock(), when
+ * they are calling trylock after adding themself to the waitlist and
+ * prior to sleeping.
+ *
+ * Therefore, if we fail to get the lock, and there were waiters of the
+ * type we conflict with, we will have to issue a wakeup.
+ *
+ * Since we may be called under wait_lock (and by the wakeup code
+ * itself), we return that the wakeup has to be done instead of doing it
+ * here.
*/
-
if (type == SIX_LOCK_read && lock->readers) {
preempt_disable();
this_cpu_inc(*lock->readers); /* signal that we own lock */
smp_mb();
- old.v = READ_ONCE(lock->state.v);
- ret = !(old.v & l[type].lock_fail);
+ old = atomic_read(&lock->state);
+ ret = !(old & l[type].lock_fail);
this_cpu_sub(*lock->readers, !ret);
preempt_enable();
- /*
- * If we failed because a writer was trying to take the
- * lock, issue a wakeup because we might have caused a
- * spurious trylock failure:
- */
-#if 0
- /*
- * This code should be sufficient, but we're seeing unexplained
- * lost wakeups:
- */
- if (old.write_locking)
+ if (!ret && (old & SIX_LOCK_WAITING_write))
ret = -1 - SIX_LOCK_write;
-#else
- if (!ret)
- ret = -1 - SIX_LOCK_write;
-#endif
} else if (type == SIX_LOCK_write && lock->readers) {
if (try) {
- atomic64_add(__SIX_VAL(write_locking, 1),
- &lock->state.counter);
- smp_mb__after_atomic();
- } else if (!(lock->state.waiters & (1 << SIX_LOCK_write))) {
- atomic64_add(__SIX_VAL(waiters, 1 << SIX_LOCK_write),
- &lock->state.counter);
- /*
- * pairs with barrier after unlock and before checking
- * for readers in unlock path
- */
+ atomic_add(SIX_LOCK_HELD_write, &lock->state);
smp_mb__after_atomic();
}
ret = !pcpu_read_count(lock);
- /*
- * On success, we increment lock->seq; also we clear
- * write_locking unless we failed from the lock path:
- */
- v = 0;
- if (ret)
- v += __SIX_VAL(seq, 1);
- if (ret || try)
- v -= __SIX_VAL(write_locking, 1);
-
if (try && !ret) {
- old.v = atomic64_add_return(v, &lock->state.counter);
- if (old.waiters & (1 << SIX_LOCK_read))
+ old = atomic_sub_return(SIX_LOCK_HELD_write, &lock->state);
+ if (old & SIX_LOCK_WAITING_read)
ret = -1 - SIX_LOCK_read;
- } else {
- atomic64_add(v, &lock->state.counter);
}
} else {
- v = READ_ONCE(lock->state.v);
+ v = atomic_read(&lock->state);
do {
- new.v = old.v = v;
+ new = old = v;
- if (!(old.v & l[type].lock_fail)) {
- new.v += l[type].lock_val;
+ ret = !(old & l[type].lock_fail);
- if (type == SIX_LOCK_write)
- new.write_locking = 0;
- } else if (!try && !(new.waiters & (1 << type)))
- new.waiters |= 1 << type;
- else
- break; /* waiting bit already set */
- } while ((v = atomic64_cmpxchg_acquire(&lock->state.counter,
- old.v, new.v)) != old.v);
+ if (!ret || (type == SIX_LOCK_write && !try)) {
+ smp_mb();
+ break;
+ }
- ret = !(old.v & l[type].lock_fail);
+ new += l[type].lock_val;
+ } while ((v = atomic_cmpxchg_acquire(&lock->state, old, new)) != old);
- EBUG_ON(ret && !(lock->state.v & 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) && (lock->state.write_locking));
+ EBUG_ON(type == SIX_LOCK_write && try && ret <= 0 &&
+ (atomic_read(&lock->state) & SIX_LOCK_HELD_write));
return ret;
}
-static inline void __six_lock_wakeup(struct six_lock *lock, enum six_lock_type lock_type)
+static void __six_lock_wakeup(struct six_lock *lock, enum six_lock_type lock_type)
{
struct six_lock_waiter *w, *next;
struct task_struct *task;
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;
wake_up_process(task);
}
- clear_bit(waitlist_bitnr(lock_type), (unsigned long *) &lock->state.v);
+ six_clear_bitmask(lock, SIX_LOCK_WAITING_read << lock_type);
unlock:
raw_spin_unlock(&lock->wait_lock);
}
}
-static inline void six_lock_wakeup(struct six_lock *lock,
- union six_lock_state state,
- enum six_lock_type lock_type)
+__always_inline
+static void six_lock_wakeup(struct six_lock *lock, u32 state,
+ enum six_lock_type lock_type)
{
- if (lock_type == SIX_LOCK_write && state.read_lock)
+ if (lock_type == SIX_LOCK_write && (state & SIX_LOCK_HELD_read))
return;
- if (!(state.waiters & (1 << lock_type)))
+ if (!(state & (SIX_LOCK_WAITING_read << lock_type)))
return;
__six_lock_wakeup(lock, lock_type);
}
-static bool do_six_trylock_type(struct six_lock *lock,
- enum six_lock_type type,
- bool try)
+__always_inline
+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;
}
-__always_inline __flatten
-static bool __six_trylock_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;
}
-
-__always_inline __flatten
-static bool __six_relock_type(struct six_lock *lock, enum six_lock_type type,
- unsigned seq, unsigned long ip)
+EXPORT_SYMBOL_GPL(six_trylock_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;
- union six_lock_state old;
- u64 v;
-
- EBUG_ON(type == SIX_LOCK_write);
-
- if (type == SIX_LOCK_read &&
- lock->readers) {
- bool ret;
-
- preempt_disable();
- this_cpu_inc(*lock->readers);
-
- smp_mb();
-
- old.v = READ_ONCE(lock->state.v);
- ret = !(old.v & l[type].lock_fail) && old.seq == seq;
-
- this_cpu_sub(*lock->readers, !ret);
- preempt_enable();
-
- /*
- * Similar to the lock path, we may have caused a spurious write
- * lock fail and need to issue a wakeup:
- */
- if (ret)
- six_acquire(&lock->dep_map, 1, type == SIX_LOCK_read, ip);
- else
- six_lock_wakeup(lock, old, SIX_LOCK_write);
+ if (lock->seq != seq || !six_trylock_ip(lock, type, ip))
+ return false;
- return ret;
+ if (lock->seq != seq) {
+ six_unlock_ip(lock, type, ip);
+ return false;
}
- v = READ_ONCE(lock->state.v);
- do {
- old.v = v;
-
- if (old.seq != seq || old.v & l[type].lock_fail)
- return false;
- } while ((v = atomic64_cmpxchg_acquire(&lock->state.counter,
- old.v,
- old.v + l[type].lock_val)) != old.v);
-
- 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);
#ifdef CONFIG_LOCK_SPIN_ON_OWNER
return ret;
}
-static inline void six_set_nospin(struct six_lock *lock)
-{
- union six_lock_state old, new;
- u64 v = READ_ONCE(lock->state.v);
-
- do {
- new.v = old.v = v;
- new.nospin = true;
- } while ((v = atomic64_cmpxchg(&lock->state.counter, old.v, new.v)) != old.v);
-}
-
static inline bool six_spin_on_owner(struct six_lock *lock,
struct task_struct *owner,
u64 end_time)
}
if (!(++loop & 0xf) && (time_after64(sched_clock(), end_time))) {
- six_set_nospin(lock);
+ six_set_bitmask(lock, SIX_LOCK_NOSPIN);
ret = false;
break;
}
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;
#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)
{
- union six_lock_state old;
int ret = 0;
if (type == SIX_LOCK_write) {
- EBUG_ON(lock->state.write_locking);
- atomic64_add(__SIX_VAL(write_locking, 1), &lock->state.counter);
+ EBUG_ON(atomic_read(&lock->state) & SIX_LOCK_HELD_write);
+ atomic_add(SIX_LOCK_HELD_write, &lock->state);
smp_mb__after_atomic();
}
wait->lock_acquired = false;
raw_spin_lock(&lock->wait_lock);
- if (!(lock->state.waiters & (1 << type)))
- set_bit(waitlist_bitnr(type), (unsigned long *) &lock->state.v);
+ six_set_bitmask(lock, SIX_LOCK_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();
list_del(&wait->list);
raw_spin_unlock(&lock->wait_lock);
- if (wait->lock_acquired)
+ if (unlikely(wait->lock_acquired))
do_six_unlock_type(lock, type);
break;
}
__set_current_state(TASK_RUNNING);
out:
- if (ret && type == SIX_LOCK_write && lock->state.write_locking) {
- old.v = atomic64_sub_return(__SIX_VAL(write_locking, 1),
- &lock->state.counter);
- six_lock_wakeup(lock, old, SIX_LOCK_read);
+ if (ret && type == SIX_LOCK_write) {
+ six_clear_bitmask(lock, SIX_LOCK_HELD_write);
+ six_lock_wakeup(lock, atomic_read(&lock->state), SIX_LOCK_read);
}
trace_contention_end(lock, 0);
return ret;
}
-__always_inline __flatten
-static 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,
- 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;
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);
return ret;
}
+EXPORT_SYMBOL_GPL(six_lock_ip_waiter);
__always_inline
-static int __six_lock_type(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_waiter(lock, type, &wait, should_sleep_fn, p, ip);
-}
-
-__always_inline __flatten
static void do_six_unlock_type(struct six_lock *lock, enum six_lock_type type)
{
const struct six_lock_vals l[] = LOCK_VALS;
- union six_lock_state state;
+ u32 state;
if (type == SIX_LOCK_intent)
lock->owner = NULL;
smp_mb(); /* unlock barrier */
this_cpu_dec(*lock->readers);
smp_mb(); /* between unlocking and checking for waiters */
- state.v = READ_ONCE(lock->state.v);
+ state = atomic_read(&lock->state);
} else {
- u64 v = l[type].unlock_val;
+ u32 v = l[type].lock_val;
if (type != SIX_LOCK_read)
- v -= lock->state.v & __SIX_VAL(nospin, 1);
+ v += atomic_read(&lock->state) & SIX_LOCK_NOSPIN;
- EBUG_ON(!(lock->state.v & l[type].held_mask));
- state.v = atomic64_add_return_release(v, &lock->state.counter);
+ 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);
}
-__always_inline __flatten
-static void __six_unlock_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 &&
- !(lock->state.v & __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);
return;
}
+ lock->seq += type == SIX_LOCK_write;
+
do_six_unlock_type(lock, type);
}
+EXPORT_SYMBOL_GPL(six_unlock_ip);
-#define __SIX_LOCK(type) \
-bool six_trylock_ip_##type(struct six_lock *lock, unsigned long ip) \
-{ \
- return __six_trylock_type(lock, SIX_LOCK_##type, ip); \
-} \
-EXPORT_SYMBOL_GPL(six_trylock_ip_##type); \
- \
-bool six_relock_ip_##type(struct six_lock *lock, u32 seq, unsigned long ip)\
-{ \
- return __six_relock_type(lock, SIX_LOCK_##type, seq, ip); \
-} \
-EXPORT_SYMBOL_GPL(six_relock_ip_##type); \
- \
-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_type(lock, SIX_LOCK_##type, should_sleep_fn, p, ip);\
-} \
-EXPORT_SYMBOL_GPL(six_lock_ip_##type); \
- \
-int six_lock_ip_waiter_##type(struct six_lock *lock, \
- struct six_lock_waiter *wait, \
- six_lock_should_sleep_fn should_sleep_fn, void *p,\
- unsigned long ip) \
-{ \
- return __six_lock_type_waiter(lock, SIX_LOCK_##type, wait, should_sleep_fn, p, ip);\
-} \
-EXPORT_SYMBOL_GPL(six_lock_ip_waiter_##type); \
- \
-void six_unlock_ip_##type(struct six_lock *lock, unsigned long ip) \
-{ \
- __six_unlock_type(lock, SIX_LOCK_##type, ip); \
-} \
-EXPORT_SYMBOL_GPL(six_unlock_ip_##type);
-
-__SIX_LOCK(read)
-__SIX_LOCK(intent)
-__SIX_LOCK(write)
-
-#undef __SIX_LOCK
-
-/* 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);
}
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)
{
- union six_lock_state old, new;
- u64 v = READ_ONCE(lock->state.v);
+ const struct six_lock_vals l[] = LOCK_VALS;
+ u32 old, new, v = atomic_read(&lock->state);
do {
- new.v = old.v = v;
+ new = old = v;
- if (new.intent_lock)
+ if (new & SIX_LOCK_HELD_intent)
return false;
if (!lock->readers) {
- EBUG_ON(!new.read_lock);
- new.read_lock--;
+ EBUG_ON(!(new & SIX_LOCK_HELD_read));
+ new -= l[SIX_LOCK_read].lock_val;
}
- new.intent_lock = 1;
- } while ((v = atomic64_cmpxchg_acquire(&lock->state.counter,
- old.v, new.v)) != old.v);
+ new |= SIX_LOCK_HELD_intent;
+ } while ((v = atomic_cmpxchg_acquire(&lock->state, old, new)) != old);
if (lock->readers)
this_cpu_dec(*lock->readers);
}
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)
}
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)
{
if (lock->readers) {
this_cpu_inc(*lock->readers);
} else {
- EBUG_ON(!lock->state.read_lock &&
- !lock->state.intent_lock);
- atomic64_add(l[type].lock_val, &lock->state.counter);
+ EBUG_ON(!(atomic_read(&lock->state) &
+ (SIX_LOCK_HELD_read|
+ SIX_LOCK_HELD_intent)));
+ atomic_add(l[type].lock_val, &lock->state);
}
break;
case SIX_LOCK_intent:
- EBUG_ON(!lock->state.intent_lock);
+ EBUG_ON(!(atomic_read(&lock->state) & SIX_LOCK_HELD_intent));
lock->intent_lock_recurse++;
break;
case SIX_LOCK_write:
}
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)
{
- union six_lock_state state = lock->state;
+ u32 state = atomic_read(&lock->state);
struct six_lock_waiter *w;
six_lock_wakeup(lock, state, SIX_LOCK_read);
}
EXPORT_SYMBOL_GPL(six_lock_wakeup_all);
-void six_lock_pcpu_free(struct six_lock *lock)
-{
- BUG_ON(lock->readers && pcpu_read_count(lock));
- BUG_ON(lock->state.read_lock);
-
- free_percpu(lock->readers);
- lock->readers = NULL;
-}
-EXPORT_SYMBOL_GPL(six_lock_pcpu_free);
-
-void six_lock_pcpu_alloc(struct six_lock *lock)
-{
-#ifdef __KERNEL__
- if (!lock->readers)
- lock->readers = alloc_percpu(unsigned);
-#endif
-}
-EXPORT_SYMBOL_GPL(six_lock_pcpu_alloc);
-
-/*
- * 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)
{
struct six_lock_count ret;
ret.n[SIX_LOCK_read] = !lock->readers
- ? lock->state.read_lock
+ ? atomic_read(&lock->state) & SIX_LOCK_HELD_read
: pcpu_read_count(lock);
- ret.n[SIX_LOCK_intent] = lock->state.intent_lock + lock->intent_lock_recurse;
- ret.n[SIX_LOCK_write] = lock->state.seq & 1;
+ ret.n[SIX_LOCK_intent] = !!(atomic_read(&lock->state) & SIX_LOCK_HELD_intent) +
+ lock->intent_lock_recurse;
+ ret.n[SIX_LOCK_write] = !!(atomic_read(&lock->state) & SIX_LOCK_HELD_write);
return ret;
}
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) {
+ this_cpu_add(*lock->readers, nr);
+ } else {
+ EBUG_ON((int) (atomic_read(&lock->state) & SIX_LOCK_HELD_read) + nr < 0);
+ /* reader count starts at bit 0 */
+ atomic_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));
+ WARN_ON(atomic_read(&lock->state) & SIX_LOCK_HELD_read);
+
+ free_percpu(lock->readers);
+ lock->readers = NULL;
+}
+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)
+{
+ atomic_set(&lock->state, 0);
+ raw_spin_lock_init(&lock->wait_lock);
+ INIT_LIST_HEAD(&lock->wait_list);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ debug_check_no_locks_freed((void *) lock, sizeof(*lock));
+ lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
+
+ if (flags & SIX_LOCK_INIT_PCPU) {
+ /*
+ * We don't return an error here on memory allocation failure
+ * since percpu is an optimization, and locks will work with the
+ * same semantics in non-percpu mode: callers can check for
+ * failure if they wish by checking lock->readers, but generally
+ * will not want to treat it as an error.
+ */
+ lock->readers = alloc_percpu(unsigned);
+ }
+}
+EXPORT_SYMBOL_GPL(__six_lock_init);
projects / bcachefs-tools-debian / commitdiff