threeeye
bc1d038eac
Squashed backup commit (no shallow-clone history issues) of xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2 branch, upstream commit 9eece662e) plus all fixes applied to get everpal_defconfig building clean against a modern (GCC 15.2.0) toolchain -- see the previous commit message on the lineage-23.2 branch (also in this repo history is not available here since this is a squashed snapshot; full incremental history lives in the local DL380 checkout and the upstream GitHub remote). Upstream: https://github.com/xiaomi-mt6833-dev/kernel_xiaomi_mt6833 (lineage-23.2)
69 lines
1.7 KiB
C
69 lines
1.7 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);
|
|
|
|
/* It's the lock irq safe version of _atomic_dec_and_lock */
|
|
int _atomic_dec_and_lock_irqsafe(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_irqsafe);
|
|
|
|
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);
|