linux_dsm_epyc7002/arch/blackfin/include/asm/spinlock.h
Peter Zijlstra 726328d92a locking/spinlock, arch: Update and fix spin_unlock_wait() implementations
This patch updates/fixes all spin_unlock_wait() implementations.

The update is in semantics; where it previously was only a control
dependency, we now upgrade to a full load-acquire to match the
store-release from the spin_unlock() we waited on. This ensures that
when spin_unlock_wait() returns, we're guaranteed to observe the full
critical section we waited on.

This fixes a number of spin_unlock_wait() users that (not
unreasonably) rely on this.

I also fixed a number of ticket lock versions to only wait on the
current lock holder, instead of for a full unlock, as this is
sufficient.

Furthermore; again for ticket locks; I added an smp_rmb() in between
the initial ticket load and the spin loop testing the current value
because I could not convince myself the address dependency is
sufficient, esp. if the loads are of different sizes.

I'm more than happy to remove this smp_rmb() again if people are
certain the address dependency does indeed work as expected.

Note: PPC32 will be fixed independently

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: chris@zankel.net
Cc: cmetcalf@mellanox.com
Cc: davem@davemloft.net
Cc: dhowells@redhat.com
Cc: james.hogan@imgtec.com
Cc: jejb@parisc-linux.org
Cc: linux@armlinux.org.uk
Cc: mpe@ellerman.id.au
Cc: ralf@linux-mips.org
Cc: realmz6@gmail.com
Cc: rkuo@codeaurora.org
Cc: rth@twiddle.net
Cc: schwidefsky@de.ibm.com
Cc: tony.luck@intel.com
Cc: vgupta@synopsys.com
Cc: ysato@users.sourceforge.jp
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-06-14 11:55:15 +02:00

107 lines
2.5 KiB
C

/*
* Copyright 2004-2009 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*/
#ifndef __BFIN_SPINLOCK_H
#define __BFIN_SPINLOCK_H
#ifndef CONFIG_SMP
# include <asm-generic/spinlock.h>
#else
#include <linux/atomic.h>
#include <asm/processor.h>
#include <asm/barrier.h>
asmlinkage int __raw_spin_is_locked_asm(volatile int *ptr);
asmlinkage void __raw_spin_lock_asm(volatile int *ptr);
asmlinkage int __raw_spin_trylock_asm(volatile int *ptr);
asmlinkage void __raw_spin_unlock_asm(volatile int *ptr);
asmlinkage void __raw_read_lock_asm(volatile int *ptr);
asmlinkage int __raw_read_trylock_asm(volatile int *ptr);
asmlinkage void __raw_read_unlock_asm(volatile int *ptr);
asmlinkage void __raw_write_lock_asm(volatile int *ptr);
asmlinkage int __raw_write_trylock_asm(volatile int *ptr);
asmlinkage void __raw_write_unlock_asm(volatile int *ptr);
static inline int arch_spin_is_locked(arch_spinlock_t *lock)
{
return __raw_spin_is_locked_asm(&lock->lock);
}
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
__raw_spin_lock_asm(&lock->lock);
}
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
return __raw_spin_trylock_asm(&lock->lock);
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
__raw_spin_unlock_asm(&lock->lock);
}
static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
{
smp_cond_load_acquire(&lock->lock, !VAL);
}
static inline int arch_read_can_lock(arch_rwlock_t *rw)
{
return __raw_uncached_fetch_asm(&rw->lock) > 0;
}
static inline int arch_write_can_lock(arch_rwlock_t *rw)
{
return __raw_uncached_fetch_asm(&rw->lock) == RW_LOCK_BIAS;
}
static inline void arch_read_lock(arch_rwlock_t *rw)
{
__raw_read_lock_asm(&rw->lock);
}
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
return __raw_read_trylock_asm(&rw->lock);
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
__raw_read_unlock_asm(&rw->lock);
}
static inline void arch_write_lock(arch_rwlock_t *rw)
{
__raw_write_lock_asm(&rw->lock);
}
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
return __raw_write_trylock_asm(&rw->lock);
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
__raw_write_unlock_asm(&rw->lock);
}
#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
#endif
#endif /* !__BFIN_SPINLOCK_H */