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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
83 lines
2.0 KiB
C
83 lines
2.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/export.h>
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#include <linux/spinlock.h>
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#include <linux/atomic.h>
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/*
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* This is an implementation of the notion of "decrement a
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* reference count, and return locked if it decremented to zero".
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*
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* NOTE NOTE NOTE! This is _not_ equivalent to
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*
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* if (atomic_dec_and_test(&atomic)) {
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* spin_lock(&lock);
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* return 1;
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* }
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* return 0;
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*
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* because the spin-lock and the decrement must be
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* "atomic".
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*/
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int atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
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{
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/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
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if (atomic_add_unless(atomic, -1, 1))
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return 0;
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/* Otherwise do it the slow way */
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spin_lock(lock);
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if (atomic_dec_and_test(atomic))
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return 1;
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spin_unlock(lock);
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return 0;
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}
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EXPORT_SYMBOL(atomic_dec_and_lock);
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int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
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unsigned long *flags)
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{
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/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
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if (atomic_add_unless(atomic, -1, 1))
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return 0;
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/* Otherwise do it the slow way */
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spin_lock_irqsave(lock, *flags);
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if (atomic_dec_and_test(atomic))
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return 1;
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spin_unlock_irqrestore(lock, *flags);
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return 0;
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}
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EXPORT_SYMBOL(_atomic_dec_and_lock_irqsave);
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int atomic_dec_and_raw_lock(atomic_t *atomic, raw_spinlock_t *lock)
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{
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/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
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if (atomic_add_unless(atomic, -1, 1))
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return 0;
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/* Otherwise do it the slow way */
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raw_spin_lock(lock);
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if (atomic_dec_and_test(atomic))
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return 1;
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raw_spin_unlock(lock);
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return 0;
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}
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EXPORT_SYMBOL(atomic_dec_and_raw_lock);
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int _atomic_dec_and_raw_lock_irqsave(atomic_t *atomic, raw_spinlock_t *lock,
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unsigned long *flags)
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{
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/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
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if (atomic_add_unless(atomic, -1, 1))
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return 0;
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/* Otherwise do it the slow way */
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raw_spin_lock_irqsave(lock, *flags);
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if (atomic_dec_and_test(atomic))
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return 1;
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raw_spin_unlock_irqrestore(lock, *flags);
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return 0;
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}
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EXPORT_SYMBOL(_atomic_dec_and_raw_lock_irqsave);
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