summaryrefslogtreecommitdiffstats
path: root/include/asm-generic/qrwlock.h
diff options
context:
space:
mode:
authorSang-Heon Jeon <ekffu200098@gmail.com>2026-08-24 01:18:14 +0900
committerJulia Lawall <Julia.Lawall@inria.fr>2026-08-23 22:12:11 +0200
commit2bd30b8dc75b823dd7bbef9d7bc68e1fd7ecee5c (patch)
treedcc4da1d99f17541c5590ac63c77da4bf372a4ab /include/asm-generic/qrwlock.h
downloadlinux-stable-2bd30b8dc75b823dd7bbef9d7bc68e1fd7ecee5c.tar.gz
linux-stable-2bd30b8dc75b823dd7bbef9d7bc68e1fd7ecee5c.zip
coccinelle: alloc_cast: drop removed allocatorsgrafted
- pci_alloc_consistent() and pci_zalloc_consistent() were removed by commit 7968778914e5 ("PCI: Remove the deprecated "pci-dma-compat.h" API") - kmem_alloc() was removed by commit f078d4ea8276 ("xfs: convert kmem_alloc() to kmalloc()") - kmem_zalloc() was removed by commit 10634530f7ba ("xfs: convert kmem_zalloc() to kzalloc()") - kmem_zone_alloc() and kmem_zone_zalloc() were removed by commit bae633a4a283 ("xfs: remove xfs_zone_{alloc,zalloc} helpers") So drop them from the rules. No functional change. Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com> Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Diffstat (limited to 'include/asm-generic/qrwlock.h')
-rw-r--r--include/asm-generic/qrwlock.h147
1 files changed, 147 insertions, 0 deletions
diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
new file mode 100644
index 000000000..75b8f4601
--- /dev/null
+++ b/include/asm-generic/qrwlock.h
@@ -0,0 +1,147 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Queue read/write lock
+ *
+ * These use generic atomic and locking routines, but depend on a fair spinlock
+ * implementation in order to be fair themselves. The implementation in
+ * asm-generic/spinlock.h meets these requirements.
+ *
+ * (C) Copyright 2013-2014 Hewlett-Packard Development Company, L.P.
+ *
+ * Authors: Waiman Long <waiman.long@hp.com>
+ */
+#ifndef __ASM_GENERIC_QRWLOCK_H
+#define __ASM_GENERIC_QRWLOCK_H
+
+#include <linux/atomic.h>
+#include <asm/barrier.h>
+#include <asm/processor.h>
+
+#include <asm-generic/qrwlock_types.h>
+
+/* Must be included from asm/spinlock.h after defining arch_spin_is_locked. */
+
+/*
+ * Writer states & reader shift and bias.
+ */
+#define _QW_WAITING 0x100 /* A writer is waiting */
+#define _QW_LOCKED 0x0ff /* A writer holds the lock */
+#define _QW_WMASK 0x1ff /* Writer mask */
+#define _QR_SHIFT 9 /* Reader count shift */
+#define _QR_BIAS (1U << _QR_SHIFT)
+
+/*
+ * External function declarations
+ */
+extern void queued_read_lock_slowpath(struct qrwlock *lock);
+extern void queued_write_lock_slowpath(struct qrwlock *lock);
+
+/**
+ * queued_read_trylock - try to acquire read lock of a queued rwlock
+ * @lock : Pointer to queued rwlock structure
+ * Return: 1 if lock acquired, 0 if failed
+ */
+static inline int queued_read_trylock(struct qrwlock *lock)
+{
+ int cnts;
+
+ cnts = atomic_read(&lock->cnts);
+ if (likely(!(cnts & _QW_WMASK))) {
+ cnts = (u32)atomic_add_return_acquire(_QR_BIAS, &lock->cnts);
+ if (likely(!(cnts & _QW_WMASK)))
+ return 1;
+ atomic_sub(_QR_BIAS, &lock->cnts);
+ }
+ return 0;
+}
+
+/**
+ * queued_write_trylock - try to acquire write lock of a queued rwlock
+ * @lock : Pointer to queued rwlock structure
+ * Return: 1 if lock acquired, 0 if failed
+ */
+static inline int queued_write_trylock(struct qrwlock *lock)
+{
+ int cnts;
+
+ cnts = atomic_read(&lock->cnts);
+ if (unlikely(cnts))
+ return 0;
+
+ return likely(atomic_try_cmpxchg_acquire(&lock->cnts, &cnts,
+ _QW_LOCKED));
+}
+/**
+ * queued_read_lock - acquire read lock of a queued rwlock
+ * @lock: Pointer to queued rwlock structure
+ */
+static inline void queued_read_lock(struct qrwlock *lock)
+{
+ int cnts;
+
+ cnts = atomic_add_return_acquire(_QR_BIAS, &lock->cnts);
+ if (likely(!(cnts & _QW_WMASK)))
+ return;
+
+ /* The slowpath will decrement the reader count, if necessary. */
+ queued_read_lock_slowpath(lock);
+}
+
+/**
+ * queued_write_lock - acquire write lock of a queued rwlock
+ * @lock : Pointer to queued rwlock structure
+ */
+static inline void queued_write_lock(struct qrwlock *lock)
+{
+ int cnts = 0;
+ /* Optimize for the unfair lock case where the fair flag is 0. */
+ if (likely(atomic_try_cmpxchg_acquire(&lock->cnts, &cnts, _QW_LOCKED)))
+ return;
+
+ queued_write_lock_slowpath(lock);
+}
+
+/**
+ * queued_read_unlock - release read lock of a queued rwlock
+ * @lock : Pointer to queued rwlock structure
+ */
+static inline void queued_read_unlock(struct qrwlock *lock)
+{
+ /*
+ * Atomically decrement the reader count
+ */
+ (void)atomic_sub_return_release(_QR_BIAS, &lock->cnts);
+}
+
+/**
+ * queued_write_unlock - release write lock of a queued rwlock
+ * @lock : Pointer to queued rwlock structure
+ */
+static inline void queued_write_unlock(struct qrwlock *lock)
+{
+ smp_store_release(&lock->wlocked, 0);
+}
+
+/**
+ * queued_rwlock_is_contended - check if the lock is contended
+ * @lock : Pointer to queued rwlock structure
+ * Return: 1 if lock contended, 0 otherwise
+ */
+static inline int queued_rwlock_is_contended(struct qrwlock *lock)
+{
+ return arch_spin_is_locked(&lock->wait_lock);
+}
+
+/*
+ * Remapping rwlock architecture specific functions to the corresponding
+ * queued rwlock functions.
+ */
+#define arch_read_lock(l) queued_read_lock(l)
+#define arch_write_lock(l) queued_write_lock(l)
+#define arch_read_trylock(l) queued_read_trylock(l)
+#define arch_write_trylock(l) queued_write_trylock(l)
+#define arch_read_unlock(l) queued_read_unlock(l)
+#define arch_write_unlock(l) queued_write_unlock(l)
+#define arch_rwlock_is_contended(l) queued_rwlock_is_contended(l)
+
+#endif /* __ASM_GENERIC_QRWLOCK_H */