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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-19 10:09:22 -0700
commitf4cdf7ca9a1fdcca413157df19753f388a5a224e (patch)
tree60a31895b2446cd7fa27514e8c2843534a0de0da /include/asm-generic/qspinlock.h
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Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted
Pull media updates from Mauro Carvalho Chehab: - v4l2-core: added ISP statistics support and per-block validation - v4l2-core: Allow unknown HDR10 white point and luminance - New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor - New codec: Milos: VPU v2.0 codec support - isp driver: gained support for Dreamchip RPPX1 ISP framework - vsp1 driver: gained support for RZ/T2H and RZ/N2H - Novalake driver: gained CVS support for new NVL hardware - dvb-core: fix feed leak on failed DMX_ADD_PID - several driver fixes, cleanups and minor improvements * tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits) media: ipu-bridge: check all DMI entries when overriding sensor rotation media: v4l2-async: avoid deleting unlinked ASC entry on link error media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement media: intel/ipu6: fix async notifier cleanup leak on parse error media: staging/ipu7: fix async notifier UAF on probe error path media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem() media: rcar-isp: Fix VSPX reference leaks media: rcar-isp: Release ISPCORE resources media: i2c: imx415: Release runtime PM reference on VBLANK error media: i2c: imx415: Return test pattern write errors media: renesas: vsp1: Declare index variables in for loop statement media: renesas: vsp1: Make reset control optional to support platforms without a reset line media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs media: nxp: imx8-isi: Add additional 32-bit RGB format support media: nxp: imx8-isi: Add 16-bit raw Bayer format support media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks media: nxp: imx8-isi: Correct color map between V4L2 and ISI ...
Diffstat (limited to 'include/asm-generic/qspinlock.h')
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diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h
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+++ b/include/asm-generic/qspinlock.h
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+/* 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>
+#include <linux/tracepoint-defs.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_release
+/**
+ * queued_spin_release - release a queued spinlock
+ * @lock : Pointer to queued spinlock structure
+ */
+static __always_inline void queued_spin_release(struct qspinlock *lock)
+{
+ /*
+ * unlock() needs release semantics:
+ */
+ smp_store_release(&lock->locked, 0);
+}
+#endif
+
+#ifndef queued_spin_unlock
+
+DECLARE_TRACEPOINT(contended_release);
+
+extern void queued_spin_release_traced(struct qspinlock *lock);
+
+/**
+ * queued_spin_unlock - unlock a queued spinlock
+ * @lock : Pointer to queued spinlock structure
+ *
+ * Generic tracing wrapper around the arch-overridable
+ * queued_spin_release().
+ */
+static __always_inline void queued_spin_unlock(struct qspinlock *lock)
+{
+ /*
+ * Trace and release are combined in queued_spin_release_traced() so
+ * the compiler does not need to preserve the lock pointer across the
+ * function call, avoiding callee-saved register save/restore on the
+ * hot path. queued_spin_release() is therefore called both here and in
+ * queued_spin_release_traced(). Keep the two in sync.
+ */
+ if (IS_ENABLED(CONFIG_QUEUED_SPINLOCKS_TRACE_CONTENDED_RELEASE) &&
+ tracepoint_enabled(contended_release)) {
+ queued_spin_release_traced(lock);
+ return;
+ }
+ queued_spin_release(lock);
+}
+#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 */