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e4588c25c9
As discussed in [1], removing __cond_lock() will improve the readability of trylock code. Now that Sparse context tracking support has been removed, we can also remove __cond_lock(). Change existing APIs to either drop __cond_lock() completely, or make use of the __cond_acquires() function attribute instead. In particular, spinlock and rwlock implementations required switching over to inline helpers rather than statement-expressions for their trylock_* variants. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/all/20250207082832.GU7145@noisy.programming.kicks-ass.net/ [1] Link: https://patch.msgid.link/20251219154418.3592607-25-elver@google.com
64 lines
1.7 KiB
C
64 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_LOCKREF_H
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#define __LINUX_LOCKREF_H
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/*
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* Locked reference counts.
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*
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* These are different from just plain atomic refcounts in that they
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* are atomic with respect to the spinlock that goes with them. In
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* particular, there can be implementations that don't actually get
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* the spinlock for the common decrement/increment operations, but they
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* still have to check that the operation is done semantically as if
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* the spinlock had been taken (using a cmpxchg operation that covers
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* both the lock and the count word, or using memory transactions, for
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* example).
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*/
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#include <linux/spinlock.h>
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#include <generated/bounds.h>
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#define USE_CMPXCHG_LOCKREF \
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(IS_ENABLED(CONFIG_ARCH_USE_CMPXCHG_LOCKREF) && \
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IS_ENABLED(CONFIG_SMP) && SPINLOCK_SIZE <= 4)
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struct lockref {
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union {
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#if USE_CMPXCHG_LOCKREF
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aligned_u64 lock_count;
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#endif
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struct {
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spinlock_t lock;
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int count;
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};
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};
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};
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/**
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* lockref_init - Initialize a lockref
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* @lockref: pointer to lockref structure
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*
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* Initializes @lockref->count to 1.
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*/
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static inline void lockref_init(struct lockref *lockref)
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{
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spin_lock_init(&lockref->lock);
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lockref->count = 1;
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}
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void lockref_get(struct lockref *lockref);
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int lockref_put_return(struct lockref *lockref);
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bool lockref_get_not_zero(struct lockref *lockref);
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bool lockref_put_or_lock(struct lockref *lockref) __cond_acquires(false, &lockref->lock);
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void lockref_mark_dead(struct lockref *lockref);
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bool lockref_get_not_dead(struct lockref *lockref);
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/* Must be called under spinlock for reliable results */
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static inline bool __lockref_is_dead(const struct lockref *l)
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{
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return ((int)l->count < 0);
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}
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#endif /* __LINUX_LOCKREF_H */
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