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| author | Rob Herring (Arm) <robh@kernel.org> | 2026-08-31 14:43:51 -0500 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2026-09-13 18:17:31 -0700 |
| commit | 55fc280e951ab2b39f3dcb640edc1b1eebc6d173 (patch) | |
| tree | f0b5f37b42fc13b9908a31b657c646b024231cdd /include/asm-generic/qspinlock.h | |
| download | linux-stable-55fc280e951ab2b39f3dcb640edc1b1eebc6d173.tar.gz linux-stable-55fc280e951ab2b39f3dcb640edc1b1eebc6d173.zip | |
Input: tsc2007 - read "ti,poll-period" as u32grafted
The "ti,poll-period" property is documented as a normal uint32 cell.
The driver used a u64 helper, which makes the helper type disagree with
the schema even though the stored value is still small.
Read "ti,poll-period" with the u32 helper matching the documented DT
cell size.
Assisted-by: Codex:gpt-5-5
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20260831194352.1185860-1-robh@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'include/asm-generic/qspinlock.h')
| -rw-r--r-- | include/asm-generic/qspinlock.h | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h new file mode 100644 index 000000000..bf47cca2c --- /dev/null +++ b/include/asm-generic/qspinlock.h @@ -0,0 +1,152 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Queued spinlock + * + * A 'generic' spinlock implementation that is based on MCS locks. For an + * architecture that's looking for a 'generic' spinlock, please first consider + * ticket-lock.h and only come looking here when you've considered all the + * constraints below and can show your hardware does actually perform better + * with qspinlock. + * + * qspinlock relies on atomic_*_release()/atomic_*_acquire() to be RCsc (or no + * weaker than RCtso if you're power), where regular code only expects atomic_t + * to be RCpc. + * + * qspinlock relies on a far greater (compared to asm-generic/spinlock.h) set + * of atomic operations to behave well together, please audit them carefully to + * ensure they all have forward progress. Many atomic operations may default to + * cmpxchg() loops which will not have good forward progress properties on + * LL/SC architectures. + * + * One notable example is atomic_fetch_or_acquire(), which x86 cannot (cheaply) + * do. Carefully read the patches that introduced + * queued_fetch_set_pending_acquire(). + * + * qspinlock also heavily relies on mixed size atomic operations, in specific + * it requires architectures to have xchg16; something which many LL/SC + * architectures need to implement as a 32bit and+or in order to satisfy the + * forward progress guarantees mentioned above. + * + * Further reading on mixed size atomics that might be relevant: + * + * http://www.cl.cam.ac.uk/~pes20/popl17/mixed-size.pdf + * + * (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P. + * (C) Copyright 2015 Hewlett-Packard Enterprise Development LP + * + * Authors: Waiman Long <waiman.long@hpe.com> + */ +#ifndef __ASM_GENERIC_QSPINLOCK_H +#define __ASM_GENERIC_QSPINLOCK_H + +#include <asm-generic/qspinlock_types.h> +#include <linux/atomic.h> + +#ifndef queued_spin_is_locked +/** + * queued_spin_is_locked - is the spinlock locked? + * @lock: Pointer to queued spinlock structure + * Return: 1 if it is locked, 0 otherwise + */ +static __always_inline int queued_spin_is_locked(struct qspinlock *lock) +{ + /* + * Any !0 state indicates it is locked, even if _Q_LOCKED_VAL + * isn't immediately observable. + */ + return atomic_read(&lock->val); +} +#endif + +/** + * queued_spin_value_unlocked - is the spinlock structure unlocked? + * @lock: queued spinlock structure + * Return: 1 if it is unlocked, 0 otherwise + * + * N.B. Whenever there are tasks waiting for the lock, it is considered + * locked wrt the lockref code to avoid lock stealing by the lockref + * code and change things underneath the lock. This also allows some + * optimizations to be applied without conflict with lockref. + */ +static __always_inline int queued_spin_value_unlocked(struct qspinlock lock) +{ + return !lock.val.counter; +} + +/** + * queued_spin_is_contended - check if the lock is contended + * @lock : Pointer to queued spinlock structure + * Return: 1 if lock contended, 0 otherwise + */ +static __always_inline int queued_spin_is_contended(struct qspinlock *lock) +{ + return atomic_read(&lock->val) & ~_Q_LOCKED_MASK; +} +/** + * queued_spin_trylock - try to acquire the queued spinlock + * @lock : Pointer to queued spinlock structure + * Return: 1 if lock acquired, 0 if failed + */ +static __always_inline int queued_spin_trylock(struct qspinlock *lock) +{ + int val = atomic_read(&lock->val); + + if (unlikely(val)) + return 0; + + return likely(atomic_try_cmpxchg_acquire(&lock->val, &val, _Q_LOCKED_VAL)); +} + +extern void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val); + +#ifndef queued_spin_lock +/** + * queued_spin_lock - acquire a queued spinlock + * @lock: Pointer to queued spinlock structure + */ +static __always_inline void queued_spin_lock(struct qspinlock *lock) +{ + int val = 0; + + if (likely(atomic_try_cmpxchg_acquire(&lock->val, &val, _Q_LOCKED_VAL))) + return; + + queued_spin_lock_slowpath(lock, val); +} +#endif + +#ifndef queued_spin_unlock +/** + * queued_spin_unlock - release a queued spinlock + * @lock : Pointer to queued spinlock structure + */ +static __always_inline void queued_spin_unlock(struct qspinlock *lock) +{ + /* + * unlock() needs release semantics: + */ + smp_store_release(&lock->locked, 0); +} +#endif + +#ifndef virt_spin_lock +static __always_inline bool virt_spin_lock(struct qspinlock *lock) +{ + return false; +} +#endif + +#ifndef __no_arch_spinlock_redefine +/* + * Remapping spinlock architecture specific functions to the corresponding + * queued spinlock functions. + */ +#define arch_spin_is_locked(l) queued_spin_is_locked(l) +#define arch_spin_is_contended(l) queued_spin_is_contended(l) +#define arch_spin_value_unlocked(l) queued_spin_value_unlocked(l) +#define arch_spin_lock(l) queued_spin_lock(l) +#define arch_spin_trylock(l) queued_spin_trylock(l) +#define arch_spin_unlock(l) queued_spin_unlock(l) +#endif + +#endif /* __ASM_GENERIC_QSPINLOCK_H */ |
