Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "The locking tree was busier in this cycle than the usual pattern - a
  couple of major projects happened to coincide.

  The main changes are:

   - implement the atomic_fetch_{add,sub,and,or,xor}() API natively
     across all SMP architectures (Peter Zijlstra)

   - add atomic_fetch_{inc/dec}() as well, using the generic primitives
     (Davidlohr Bueso)

   - optimize various aspects of rwsems (Jason Low, Davidlohr Bueso,
     Waiman Long)

   - optimize smp_cond_load_acquire() on arm64 and implement LSE based
     atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()
     on arm64 (Will Deacon)

   - introduce smp_acquire__after_ctrl_dep() and fix various barrier
     mis-uses and bugs (Peter Zijlstra)

   - after discovering ancient spin_unlock_wait() barrier bugs in its
     implementation and usage, strengthen its semantics and update/fix
     usage sites (Peter Zijlstra)

   - optimize mutex_trylock() fastpath (Peter Zijlstra)

   - ... misc fixes and cleanups"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
  locking/atomic: Introduce inc/dec variants for the atomic_fetch_$op() API
  locking/barriers, arch/arm64: Implement LDXR+WFE based smp_cond_load_acquire()
  locking/static_keys: Fix non static symbol Sparse warning
  locking/qspinlock: Use __this_cpu_dec() instead of full-blown this_cpu_dec()
  locking/atomic, arch/tile: Fix tilepro build
  locking/atomic, arch/m68k: Remove comment
  locking/atomic, arch/arc: Fix build
  locking/Documentation: Clarify limited control-dependency scope
  locking/atomic, arch/rwsem: Employ atomic_long_fetch_add()
  locking/atomic, arch/qrwlock: Employ atomic_fetch_add_acquire()
  locking/atomic, arch/mips: Convert to _relaxed atomics
  locking/atomic, arch/alpha: Convert to _relaxed atomics
  locking/atomic: Remove the deprecated atomic_{set,clear}_mask() functions
  locking/atomic: Remove linux/atomic.h:atomic_fetch_or()
  locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()
  locking/atomic: Fix atomic64_relaxed() bits
  locking/atomic, arch/xtensa: Implement atomic_fetch_{add,sub,and,or,xor}()
  locking/atomic, arch/x86: Implement atomic{,64}_fetch_{add,sub,and,or,xor}()
  locking/atomic, arch/tile: Implement atomic{,64}_fetch_{add,sub,and,or,xor}()
  locking/atomic, arch/sparc: Implement atomic{,64}_fetch_{add,sub,and,or,xor}()
  ...
This commit is contained in:
Linus Torvalds 2016-07-25 12:41:29 -07:00
commit c86ad14d30
108 changed files with 3268 additions and 958 deletions

View file

@ -112,6 +112,62 @@ static __always_inline void atomic_long_dec(atomic_long_t *l)
ATOMIC_LONG_PFX(_dec)(v);
}
#define ATOMIC_LONG_FETCH_OP(op, mo) \
static inline long \
atomic_long_fetch_##op##mo(long i, atomic_long_t *l) \
{ \
ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \
\
return (long)ATOMIC_LONG_PFX(_fetch_##op##mo)(i, v); \
}
ATOMIC_LONG_FETCH_OP(add, )
ATOMIC_LONG_FETCH_OP(add, _relaxed)
ATOMIC_LONG_FETCH_OP(add, _acquire)
ATOMIC_LONG_FETCH_OP(add, _release)
ATOMIC_LONG_FETCH_OP(sub, )
ATOMIC_LONG_FETCH_OP(sub, _relaxed)
ATOMIC_LONG_FETCH_OP(sub, _acquire)
ATOMIC_LONG_FETCH_OP(sub, _release)
ATOMIC_LONG_FETCH_OP(and, )
ATOMIC_LONG_FETCH_OP(and, _relaxed)
ATOMIC_LONG_FETCH_OP(and, _acquire)
ATOMIC_LONG_FETCH_OP(and, _release)
ATOMIC_LONG_FETCH_OP(andnot, )
ATOMIC_LONG_FETCH_OP(andnot, _relaxed)
ATOMIC_LONG_FETCH_OP(andnot, _acquire)
ATOMIC_LONG_FETCH_OP(andnot, _release)
ATOMIC_LONG_FETCH_OP(or, )
ATOMIC_LONG_FETCH_OP(or, _relaxed)
ATOMIC_LONG_FETCH_OP(or, _acquire)
ATOMIC_LONG_FETCH_OP(or, _release)
ATOMIC_LONG_FETCH_OP(xor, )
ATOMIC_LONG_FETCH_OP(xor, _relaxed)
ATOMIC_LONG_FETCH_OP(xor, _acquire)
ATOMIC_LONG_FETCH_OP(xor, _release)
#undef ATOMIC_LONG_FETCH_OP
#define ATOMIC_LONG_FETCH_INC_DEC_OP(op, mo) \
static inline long \
atomic_long_fetch_##op##mo(atomic_long_t *l) \
{ \
ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \
\
return (long)ATOMIC_LONG_PFX(_fetch_##op##mo)(v); \
}
ATOMIC_LONG_FETCH_INC_DEC_OP(inc,)
ATOMIC_LONG_FETCH_INC_DEC_OP(inc, _relaxed)
ATOMIC_LONG_FETCH_INC_DEC_OP(inc, _acquire)
ATOMIC_LONG_FETCH_INC_DEC_OP(inc, _release)
ATOMIC_LONG_FETCH_INC_DEC_OP(dec,)
ATOMIC_LONG_FETCH_INC_DEC_OP(dec, _relaxed)
ATOMIC_LONG_FETCH_INC_DEC_OP(dec, _acquire)
ATOMIC_LONG_FETCH_INC_DEC_OP(dec, _release)
#undef ATOMIC_LONG_FETCH_INC_DEC_OP
#define ATOMIC_LONG_OP(op) \
static __always_inline void \
atomic_long_##op(long i, atomic_long_t *l) \
@ -124,9 +180,9 @@ atomic_long_##op(long i, atomic_long_t *l) \
ATOMIC_LONG_OP(add)
ATOMIC_LONG_OP(sub)
ATOMIC_LONG_OP(and)
ATOMIC_LONG_OP(andnot)
ATOMIC_LONG_OP(or)
ATOMIC_LONG_OP(xor)
ATOMIC_LONG_OP(andnot)
#undef ATOMIC_LONG_OP

View file

@ -61,6 +61,18 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
return c c_op i; \
}
#define ATOMIC_FETCH_OP(op, c_op) \
static inline int atomic_fetch_##op(int i, atomic_t *v) \
{ \
int c, old; \
\
c = v->counter; \
while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \
c = old; \
\
return c; \
}
#else
#include <linux/irqflags.h>
@ -88,6 +100,20 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \
return ret; \
}
#define ATOMIC_FETCH_OP(op, c_op) \
static inline int atomic_fetch_##op(int i, atomic_t *v) \
{ \
unsigned long flags; \
int ret; \
\
raw_local_irq_save(flags); \
ret = v->counter; \
v->counter = v->counter c_op i; \
raw_local_irq_restore(flags); \
\
return ret; \
}
#endif /* CONFIG_SMP */
#ifndef atomic_add_return
@ -98,6 +124,26 @@ ATOMIC_OP_RETURN(add, +)
ATOMIC_OP_RETURN(sub, -)
#endif
#ifndef atomic_fetch_add
ATOMIC_FETCH_OP(add, +)
#endif
#ifndef atomic_fetch_sub
ATOMIC_FETCH_OP(sub, -)
#endif
#ifndef atomic_fetch_and
ATOMIC_FETCH_OP(and, &)
#endif
#ifndef atomic_fetch_or
ATOMIC_FETCH_OP(or, |)
#endif
#ifndef atomic_fetch_xor
ATOMIC_FETCH_OP(xor, ^)
#endif
#ifndef atomic_and
ATOMIC_OP(and, &)
#endif
@ -110,6 +156,7 @@ ATOMIC_OP(or, |)
ATOMIC_OP(xor, ^)
#endif
#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP

View file

@ -27,16 +27,23 @@ extern void atomic64_##op(long long a, atomic64_t *v);
#define ATOMIC64_OP_RETURN(op) \
extern long long atomic64_##op##_return(long long a, atomic64_t *v);
#define ATOMIC64_OPS(op) ATOMIC64_OP(op) ATOMIC64_OP_RETURN(op)
#define ATOMIC64_FETCH_OP(op) \
extern long long atomic64_fetch_##op(long long a, atomic64_t *v);
#define ATOMIC64_OPS(op) ATOMIC64_OP(op) ATOMIC64_OP_RETURN(op) ATOMIC64_FETCH_OP(op)
ATOMIC64_OPS(add)
ATOMIC64_OPS(sub)
ATOMIC64_OP(and)
ATOMIC64_OP(or)
ATOMIC64_OP(xor)
#undef ATOMIC64_OPS
#define ATOMIC64_OPS(op) ATOMIC64_OP(op) ATOMIC64_FETCH_OP(op)
ATOMIC64_OPS(and)
ATOMIC64_OPS(or)
ATOMIC64_OPS(xor)
#undef ATOMIC64_OPS
#undef ATOMIC64_FETCH_OP
#undef ATOMIC64_OP_RETURN
#undef ATOMIC64_OP

View file

@ -194,7 +194,7 @@ do { \
})
#endif
#endif
#endif /* CONFIG_SMP */
/* Barriers for virtual machine guests when talking to an SMP host */
#define virt_mb() __smp_mb()
@ -207,5 +207,44 @@ do { \
#define virt_store_release(p, v) __smp_store_release(p, v)
#define virt_load_acquire(p) __smp_load_acquire(p)
/**
* smp_acquire__after_ctrl_dep() - Provide ACQUIRE ordering after a control dependency
*
* A control dependency provides a LOAD->STORE order, the additional RMB
* provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order,
* aka. (load)-ACQUIRE.
*
* Architectures that do not do load speculation can have this be barrier().
*/
#ifndef smp_acquire__after_ctrl_dep
#define smp_acquire__after_ctrl_dep() smp_rmb()
#endif
/**
* smp_cond_load_acquire() - (Spin) wait for cond with ACQUIRE ordering
* @ptr: pointer to the variable to wait on
* @cond: boolean expression to wait for
*
* Equivalent to using smp_load_acquire() on the condition variable but employs
* the control dependency of the wait to reduce the barrier on many platforms.
*
* Due to C lacking lambda expressions we load the value of *ptr into a
* pre-named variable @VAL to be used in @cond.
*/
#ifndef smp_cond_load_acquire
#define smp_cond_load_acquire(ptr, cond_expr) ({ \
typeof(ptr) __PTR = (ptr); \
typeof(*ptr) VAL; \
for (;;) { \
VAL = READ_ONCE(*__PTR); \
if (cond_expr) \
break; \
cpu_relax(); \
} \
smp_acquire__after_ctrl_dep(); \
VAL; \
})
#endif
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_GENERIC_BARRIER_H */

View file

@ -80,7 +80,7 @@ __mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
static inline int
__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
{
if (likely(atomic_cmpxchg_acquire(count, 1, 0) == 1))
if (likely(atomic_read(count) == 1 && atomic_cmpxchg_acquire(count, 1, 0) == 1))
return 1;
return 0;
}

View file

@ -91,8 +91,12 @@ __mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
static inline int
__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
{
int prev = atomic_xchg_acquire(count, 0);
int prev;
if (atomic_read(count) != 1)
return 0;
prev = atomic_xchg_acquire(count, 0);
if (unlikely(prev < 0)) {
/*
* The lock was marked contended so we must restore that

View file

@ -111,10 +111,9 @@ static __always_inline void queued_spin_lock(struct qspinlock *lock)
static __always_inline void queued_spin_unlock(struct qspinlock *lock)
{
/*
* smp_mb__before_atomic() in order to guarantee release semantics
* unlock() needs release semantics:
*/
smp_mb__before_atomic();
atomic_sub(_Q_LOCKED_VAL, &lock->val);
(void)atomic_sub_return_release(_Q_LOCKED_VAL, &lock->val);
}
#endif

View file

@ -41,8 +41,8 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
{
long tmp;
while ((tmp = sem->count) >= 0) {
if (tmp == cmpxchg_acquire(&sem->count, tmp,
while ((tmp = atomic_long_read(&sem->count)) >= 0) {
if (tmp == atomic_long_cmpxchg_acquire(&sem->count, tmp,
tmp + RWSEM_ACTIVE_READ_BIAS)) {
return 1;
}
@ -79,7 +79,7 @@ static inline int __down_write_trylock(struct rw_semaphore *sem)
{
long tmp;
tmp = cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE,
tmp = atomic_long_cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE,
RWSEM_ACTIVE_WRITE_BIAS);
return tmp == RWSEM_UNLOCKED_VALUE;
}
@ -106,14 +106,6 @@ static inline void __up_write(struct rw_semaphore *sem)
rwsem_wake(sem);
}
/*
* implement atomic add functionality
*/
static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem)
{
atomic_long_add(delta, (atomic_long_t *)&sem->count);
}
/*
* downgrade write lock to read lock
*/
@ -134,13 +126,5 @@ static inline void __downgrade_write(struct rw_semaphore *sem)
rwsem_downgrade_wake(sem);
}
/*
* implement exchange and add functionality
*/
static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
{
return atomic_long_add_return(delta, (atomic_long_t *)&sem->count);
}
#endif /* __KERNEL__ */
#endif /* _ASM_GENERIC_RWSEM_H */