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Subject[PATCH RFC 25/26] tile: Remove spin_unlock_wait() arch-specific definitions
Date
There is no agreed-upon definition of spin_unlock_wait()'s semantics,
and it appears that all callers could do just as well with a lock/unlock
pair. This commit therefore removes the underlying arch-specific
arch_spin_unlock_wait().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/tile/include/asm/spinlock_32.h | 2 --
arch/tile/include/asm/spinlock_64.h | 2 --
arch/tile/lib/spinlock_32.c | 23 -----------------------
arch/tile/lib/spinlock_64.c | 22 ----------------------
4 files changed, 49 deletions(-)

diff --git a/arch/tile/include/asm/spinlock_32.h b/arch/tile/include/asm/spinlock_32.h
index b14b1ba5bf9c..cba8ba9b8da6 100644
--- a/arch/tile/include/asm/spinlock_32.h
+++ b/arch/tile/include/asm/spinlock_32.h
@@ -64,8 +64,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
lock->current_ticket = old_ticket + TICKET_QUANTUM;
}

-void arch_spin_unlock_wait(arch_spinlock_t *lock);
-
/*
* Read-write spinlocks, allowing multiple readers
* but only one writer.
diff --git a/arch/tile/include/asm/spinlock_64.h b/arch/tile/include/asm/spinlock_64.h
index b9718fb4e74a..9a2c2d605752 100644
--- a/arch/tile/include/asm/spinlock_64.h
+++ b/arch/tile/include/asm/spinlock_64.h
@@ -58,8 +58,6 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
__insn_fetchadd4(&lock->lock, 1U << __ARCH_SPIN_CURRENT_SHIFT);
}

-void arch_spin_unlock_wait(arch_spinlock_t *lock);
-
void arch_spin_lock_slow(arch_spinlock_t *lock, u32 val);

/* Grab the "next" ticket number and bump it atomically.
diff --git a/arch/tile/lib/spinlock_32.c b/arch/tile/lib/spinlock_32.c
index 076c6cc43113..db9333f2447c 100644
--- a/arch/tile/lib/spinlock_32.c
+++ b/arch/tile/lib/spinlock_32.c
@@ -62,29 +62,6 @@ int arch_spin_trylock(arch_spinlock_t *lock)
}
EXPORT_SYMBOL(arch_spin_trylock);

-void arch_spin_unlock_wait(arch_spinlock_t *lock)
-{
- u32 iterations = 0;
- int curr = READ_ONCE(lock->current_ticket);
- int next = READ_ONCE(lock->next_ticket);
-
- /* Return immediately if unlocked. */
- if (next == curr)
- return;
-
- /* Wait until the current locker has released the lock. */
- do {
- delay_backoff(iterations++);
- } while (READ_ONCE(lock->current_ticket) == curr);
-
- /*
- * The TILE architecture doesn't do read speculation; therefore
- * a control dependency guarantees a LOAD->{LOAD,STORE} order.
- */
- barrier();
-}
-EXPORT_SYMBOL(arch_spin_unlock_wait);
-
/*
* The low byte is always reserved to be the marker for a "tns" operation
* since the low bit is set to "1" by a tns. The next seven bits are
diff --git a/arch/tile/lib/spinlock_64.c b/arch/tile/lib/spinlock_64.c
index a4b5b2cbce93..de414c22892f 100644
--- a/arch/tile/lib/spinlock_64.c
+++ b/arch/tile/lib/spinlock_64.c
@@ -62,28 +62,6 @@ int arch_spin_trylock(arch_spinlock_t *lock)
}
EXPORT_SYMBOL(arch_spin_trylock);

-void arch_spin_unlock_wait(arch_spinlock_t *lock)
-{
- u32 iterations = 0;
- u32 val = READ_ONCE(lock->lock);
- u32 curr = arch_spin_current(val);
-
- /* Return immediately if unlocked. */
- if (arch_spin_next(val) == curr)
- return;
-
- /* Wait until the current locker has released the lock. */
- do {
- delay_backoff(iterations++);
- } while (arch_spin_current(READ_ONCE(lock->lock)) == curr);
-
- /*
- * The TILE architecture doesn't do read speculation; therefore
- * a control dependency guarantees a LOAD->{LOAD,STORE} order.
- */
- barrier();
-}
-EXPORT_SYMBOL(arch_spin_unlock_wait);

/*
* If the read lock fails due to a writer, we retry periodically
--
2.5.2
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