Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
83 lines
2.0 KiB
C
83 lines
2.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/export.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/atomic.h>
|
|
|
|
/*
|
|
* This is an implementation of the notion of "decrement a
|
|
* reference count, and return locked if it decremented to zero".
|
|
*
|
|
* NOTE NOTE NOTE! This is _not_ equivalent to
|
|
*
|
|
* if (atomic_dec_and_test(&atomic)) {
|
|
* spin_lock(&lock);
|
|
* return 1;
|
|
* }
|
|
* return 0;
|
|
*
|
|
* because the spin-lock and the decrement must be
|
|
* "atomic".
|
|
*/
|
|
int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
|
|
{
|
|
/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
|
|
if (atomic_add_unless(atomic, -1, 1))
|
|
return 0;
|
|
|
|
/* Otherwise do it the slow way */
|
|
spin_lock(lock);
|
|
if (atomic_dec_and_test(atomic))
|
|
return 1;
|
|
spin_unlock(lock);
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(_atomic_dec_and_lock);
|
|
|
|
int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
|
|
unsigned long *flags)
|
|
{
|
|
/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
|
|
if (atomic_add_unless(atomic, -1, 1))
|
|
return 0;
|
|
|
|
/* Otherwise do it the slow way */
|
|
spin_lock_irqsave(lock, *flags);
|
|
if (atomic_dec_and_test(atomic))
|
|
return 1;
|
|
spin_unlock_irqrestore(lock, *flags);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(_atomic_dec_and_lock_irqsave);
|
|
|
|
int _atomic_dec_and_raw_lock(atomic_t *atomic, raw_spinlock_t *lock)
|
|
{
|
|
/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
|
|
if (atomic_add_unless(atomic, -1, 1))
|
|
return 0;
|
|
|
|
/* Otherwise do it the slow way */
|
|
raw_spin_lock(lock);
|
|
if (atomic_dec_and_test(atomic))
|
|
return 1;
|
|
raw_spin_unlock(lock);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(_atomic_dec_and_raw_lock);
|
|
|
|
int _atomic_dec_and_raw_lock_irqsave(atomic_t *atomic, raw_spinlock_t *lock,
|
|
unsigned long *flags)
|
|
{
|
|
/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
|
|
if (atomic_add_unless(atomic, -1, 1))
|
|
return 0;
|
|
|
|
/* Otherwise do it the slow way */
|
|
raw_spin_lock_irqsave(lock, *flags);
|
|
if (atomic_dec_and_test(atomic))
|
|
return 1;
|
|
raw_spin_unlock_irqrestore(lock, *flags);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(_atomic_dec_and_raw_lock_irqsave);
|