a8a217c221
Outside of the locking code itself, {read,spin,write}_can_lock() have no
users in tree. Apparmor (the last remaining user of write_can_lock()) got
moved over to lockdep by the previous patch.
This patch removes the use of {read,spin,write}_can_lock() from the
BUILD_LOCK_OPS macro, deferring to the trylock operation for testing the
lock status, and subsequently removes the unused macros altogether. They
aren't guaranteed to work in a concurrent environment and can give
incorrect results in the case of qrwlock.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: paulmck@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/1507055129-12300-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
81 lines
2.3 KiB
C
81 lines
2.3 KiB
C
#ifndef __LINUX_SPINLOCK_UP_H
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#define __LINUX_SPINLOCK_UP_H
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#ifndef __LINUX_SPINLOCK_H
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# error "please don't include this file directly"
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#endif
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#include <asm/processor.h> /* for cpu_relax() */
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#include <asm/barrier.h>
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/*
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* include/linux/spinlock_up.h - UP-debug version of spinlocks.
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*
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* portions Copyright 2005, Red Hat, Inc., Ingo Molnar
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* Released under the General Public License (GPL).
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*
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* In the debug case, 1 means unlocked, 0 means locked. (the values
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* are inverted, to catch initialization bugs)
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*
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* No atomicity anywhere, we are on UP. However, we still need
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* the compiler barriers, because we do not want the compiler to
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* move potentially faulting instructions (notably user accesses)
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* into the locked sequence, resulting in non-atomic execution.
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*/
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#ifdef CONFIG_DEBUG_SPINLOCK
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#define arch_spin_is_locked(x) ((x)->slock == 0)
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static inline void arch_spin_lock(arch_spinlock_t *lock)
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{
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lock->slock = 0;
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barrier();
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}
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static inline void
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arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
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{
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local_irq_save(flags);
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lock->slock = 0;
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barrier();
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}
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static inline int arch_spin_trylock(arch_spinlock_t *lock)
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{
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char oldval = lock->slock;
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lock->slock = 0;
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barrier();
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return oldval > 0;
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}
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static inline void arch_spin_unlock(arch_spinlock_t *lock)
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{
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barrier();
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lock->slock = 1;
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}
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/*
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* Read-write spinlocks. No debug version.
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*/
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#define arch_read_lock(lock) do { barrier(); (void)(lock); } while (0)
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#define arch_write_lock(lock) do { barrier(); (void)(lock); } while (0)
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#define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; })
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#define arch_write_trylock(lock) ({ barrier(); (void)(lock); 1; })
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#define arch_read_unlock(lock) do { barrier(); (void)(lock); } while (0)
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#define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0)
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#else /* DEBUG_SPINLOCK */
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#define arch_spin_is_locked(lock) ((void)(lock), 0)
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/* for sched/core.c and kernel_lock.c: */
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# define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0)
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# define arch_spin_lock_flags(lock, flags) do { barrier(); (void)(lock); } while (0)
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# define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0)
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# define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; })
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#endif /* DEBUG_SPINLOCK */
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#define arch_spin_is_contended(lock) (((void)(lock), 0))
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#endif /* __LINUX_SPINLOCK_UP_H */
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