472 lines
13 KiB
C
472 lines
13 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_SPINLOCK_H
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#define __LINUX_SPINLOCK_H
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/*
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* include/linux/spinlock.h - generic spinlock/rwlock declarations
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*
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* here's the role of the various spinlock/rwlock related include files:
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*
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* on SMP builds:
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*
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* asm/spinlock_types.h: contains the arch_spinlock_t/arch_rwlock_t and the
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* initializers
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*
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* linux/spinlock_types.h:
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* defines the generic type and initializers
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*
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* asm/spinlock.h: contains the arch_spin_*()/etc. lowlevel
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* implementations, mostly inline assembly code
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*
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* (also included on UP-debug builds:)
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*
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* linux/spinlock_api_smp.h:
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* contains the prototypes for the _spin_*() APIs.
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*
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* linux/spinlock.h: builds the final spin_*() APIs.
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*
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* on UP builds:
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*
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* linux/spinlock_type_up.h:
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* contains the generic, simplified UP spinlock type.
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* (which is an empty structure on non-debug builds)
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*
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* linux/spinlock_types.h:
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* defines the generic type and initializers
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*
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* linux/spinlock_up.h:
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* contains the arch_spin_*()/etc. version of UP
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* builds. (which are NOPs on non-debug, non-preempt
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* builds)
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*
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* (included on UP-non-debug builds:)
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*
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* linux/spinlock_api_up.h:
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* builds the _spin_*() APIs.
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*
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* linux/spinlock.h: builds the final spin_*() APIs.
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*/
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#include <linux/typecheck.h>
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#include <linux/preempt.h>
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#include <linux/linkage.h>
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#include <linux/compiler.h>
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#include <linux/irqflags.h>
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#include <linux/thread_info.h>
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#include <linux/kernel.h>
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#include <linux/stringify.h>
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#include <linux/bottom_half.h>
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#include <asm/barrier.h>
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/*
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* Must define these before including other files, inline functions need them
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*/
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#define LOCK_SECTION_NAME ".text..lock."KBUILD_BASENAME
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#define LOCK_SECTION_START(extra) \
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".subsection 1\n\t" \
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extra \
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".ifndef " LOCK_SECTION_NAME "\n\t" \
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LOCK_SECTION_NAME ":\n\t" \
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".endif\n"
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#define LOCK_SECTION_END \
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".previous\n\t"
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#define __lockfunc __attribute__((section(".spinlock.text")))
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/*
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* Pull the arch_spinlock_t and arch_rwlock_t definitions:
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*/
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#include <linux/spinlock_types.h>
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/*
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* Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them):
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*/
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#ifdef CONFIG_SMP
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# include <asm/spinlock.h>
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#else
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# include <linux/spinlock_up.h>
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#endif
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#ifdef CONFIG_DEBUG_SPINLOCK
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extern void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
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struct lock_class_key *key);
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# define raw_spin_lock_init(lock) \
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do { \
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static struct lock_class_key __key; \
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\
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__raw_spin_lock_init((lock), #lock, &__key); \
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} while (0)
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#else
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# define raw_spin_lock_init(lock) \
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do { *(lock) = __RAW_SPIN_LOCK_UNLOCKED(lock); } while (0)
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#endif
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#define raw_spin_is_locked(lock) arch_spin_is_locked(&(lock)->raw_lock)
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#ifdef arch_spin_is_contended
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#define raw_spin_is_contended(lock) arch_spin_is_contended(&(lock)->raw_lock)
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#else
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#define raw_spin_is_contended(lock) (((void)(lock), 0))
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#endif /*arch_spin_is_contended*/
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/*
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* smp_mb__after_spinlock() provides the equivalent of a full memory barrier
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* between program-order earlier lock acquisitions and program-order later
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* memory accesses.
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*
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* This guarantees that the following two properties hold:
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*
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* 1) Given the snippet:
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*
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* { X = 0; Y = 0; }
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*
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* CPU0 CPU1
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*
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* WRITE_ONCE(X, 1); WRITE_ONCE(Y, 1);
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* spin_lock(S); smp_mb();
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* smp_mb__after_spinlock(); r1 = READ_ONCE(X);
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* r0 = READ_ONCE(Y);
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* spin_unlock(S);
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*
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* it is forbidden that CPU0 does not observe CPU1's store to Y (r0 = 0)
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* and CPU1 does not observe CPU0's store to X (r1 = 0); see the comments
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* preceding the call to smp_mb__after_spinlock() in __schedule() and in
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* try_to_wake_up().
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*
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* 2) Given the snippet:
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*
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* { X = 0; Y = 0; }
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*
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* CPU0 CPU1 CPU2
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*
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* spin_lock(S); spin_lock(S); r1 = READ_ONCE(Y);
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* WRITE_ONCE(X, 1); smp_mb__after_spinlock(); smp_rmb();
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* spin_unlock(S); r0 = READ_ONCE(X); r2 = READ_ONCE(X);
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* WRITE_ONCE(Y, 1);
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* spin_unlock(S);
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*
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* it is forbidden that CPU0's critical section executes before CPU1's
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* critical section (r0 = 1), CPU2 observes CPU1's store to Y (r1 = 1)
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* and CPU2 does not observe CPU0's store to X (r2 = 0); see the comments
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* preceding the calls to smp_rmb() in try_to_wake_up() for similar
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* snippets but "projected" onto two CPUs.
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*
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* Property (2) upgrades the lock to an RCsc lock.
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*
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* Since most load-store architectures implement ACQUIRE with an smp_mb() after
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* the LL/SC loop, they need no further barriers. Similarly all our TSO
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* architectures imply an smp_mb() for each atomic instruction and equally don't
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* need more.
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*
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* Architectures that can implement ACQUIRE better need to take care.
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*/
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#ifndef smp_mb__after_spinlock
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#define smp_mb__after_spinlock() do { } while (0)
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#endif
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#ifdef CONFIG_DEBUG_SPINLOCK
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extern void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock);
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#define do_raw_spin_lock_flags(lock, flags) do_raw_spin_lock(lock)
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extern int do_raw_spin_trylock(raw_spinlock_t *lock);
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extern void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock);
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#else
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static inline void do_raw_spin_lock(raw_spinlock_t *lock) __acquires(lock)
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{
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__acquire(lock);
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arch_spin_lock(&lock->raw_lock);
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}
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#ifndef arch_spin_lock_flags
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#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
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#endif
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static inline void
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do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
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{
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__acquire(lock);
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arch_spin_lock_flags(&lock->raw_lock, *flags);
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}
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static inline int do_raw_spin_trylock(raw_spinlock_t *lock)
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{
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return arch_spin_trylock(&(lock)->raw_lock);
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}
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static inline void do_raw_spin_unlock(raw_spinlock_t *lock) __releases(lock)
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{
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arch_spin_unlock(&lock->raw_lock);
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__release(lock);
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}
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#endif
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/*
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* Define the various spin_lock methods. Note we define these
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* regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The
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* various methods are defined as nops in the case they are not
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* required.
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*/
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#define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock))
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#define raw_spin_lock(lock) _raw_spin_lock(lock)
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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# define raw_spin_lock_nested(lock, subclass) \
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_raw_spin_lock_nested(lock, subclass)
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# define raw_spin_lock_nest_lock(lock, nest_lock) \
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do { \
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typecheck(struct lockdep_map *, &(nest_lock)->dep_map);\
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_raw_spin_lock_nest_lock(lock, &(nest_lock)->dep_map); \
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} while (0)
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#else
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/*
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* Always evaluate the 'subclass' argument to avoid that the compiler
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* warns about set-but-not-used variables when building with
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* CONFIG_DEBUG_LOCK_ALLOC=n and with W=1.
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*/
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# define raw_spin_lock_nested(lock, subclass) \
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_raw_spin_lock(((void)(subclass), (lock)))
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# define raw_spin_lock_nest_lock(lock, nest_lock) _raw_spin_lock(lock)
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#endif
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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#define raw_spin_lock_irqsave(lock, flags) \
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do { \
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typecheck(unsigned long, flags); \
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flags = _raw_spin_lock_irqsave(lock); \
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} while (0)
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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#define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
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do { \
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typecheck(unsigned long, flags); \
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flags = _raw_spin_lock_irqsave_nested(lock, subclass); \
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} while (0)
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#else
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#define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
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do { \
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typecheck(unsigned long, flags); \
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flags = _raw_spin_lock_irqsave(lock); \
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} while (0)
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#endif
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#else
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#define raw_spin_lock_irqsave(lock, flags) \
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do { \
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typecheck(unsigned long, flags); \
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_raw_spin_lock_irqsave(lock, flags); \
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} while (0)
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#define raw_spin_lock_irqsave_nested(lock, flags, subclass) \
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raw_spin_lock_irqsave(lock, flags)
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#endif
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#define raw_spin_lock_irq(lock) _raw_spin_lock_irq(lock)
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#define raw_spin_lock_bh(lock) _raw_spin_lock_bh(lock)
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#define raw_spin_unlock(lock) _raw_spin_unlock(lock)
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#define raw_spin_unlock_irq(lock) _raw_spin_unlock_irq(lock)
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#define raw_spin_unlock_irqrestore(lock, flags) \
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do { \
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typecheck(unsigned long, flags); \
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_raw_spin_unlock_irqrestore(lock, flags); \
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} while (0)
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#define raw_spin_unlock_bh(lock) _raw_spin_unlock_bh(lock)
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#define raw_spin_trylock_bh(lock) \
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__cond_lock(lock, _raw_spin_trylock_bh(lock))
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#define raw_spin_trylock_irq(lock) \
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({ \
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local_irq_disable(); \
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raw_spin_trylock(lock) ? \
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1 : ({ local_irq_enable(); 0; }); \
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})
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#define raw_spin_trylock_irqsave(lock, flags) \
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({ \
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local_irq_save(flags); \
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raw_spin_trylock(lock) ? \
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1 : ({ local_irq_restore(flags); 0; }); \
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})
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/* Include rwlock functions */
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#include <linux/rwlock.h>
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/*
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* Pull the _spin_*()/_read_*()/_write_*() functions/declarations:
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*/
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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# include <linux/spinlock_api_smp.h>
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#else
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# include <linux/spinlock_api_up.h>
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#endif
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/*
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* Map the spin_lock functions to the raw variants for PREEMPT_RT=n
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*/
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static __always_inline raw_spinlock_t *spinlock_check(spinlock_t *lock)
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{
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return &lock->rlock;
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}
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#define spin_lock_init(_lock) \
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do { \
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spinlock_check(_lock); \
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raw_spin_lock_init(&(_lock)->rlock); \
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} while (0)
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static __always_inline void spin_lock(spinlock_t *lock)
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{
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raw_spin_lock(&lock->rlock);
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}
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static __always_inline void spin_lock_bh(spinlock_t *lock)
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{
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raw_spin_lock_bh(&lock->rlock);
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}
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static __always_inline int spin_trylock(spinlock_t *lock)
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{
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return raw_spin_trylock(&lock->rlock);
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}
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#define spin_lock_nested(lock, subclass) \
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do { \
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raw_spin_lock_nested(spinlock_check(lock), subclass); \
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} while (0)
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#define spin_lock_nest_lock(lock, nest_lock) \
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do { \
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raw_spin_lock_nest_lock(spinlock_check(lock), nest_lock); \
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} while (0)
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static __always_inline void spin_lock_irq(spinlock_t *lock)
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{
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raw_spin_lock_irq(&lock->rlock);
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}
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#define spin_lock_irqsave(lock, flags) \
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do { \
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raw_spin_lock_irqsave(spinlock_check(lock), flags); \
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} while (0)
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#define spin_lock_irqsave_nested(lock, flags, subclass) \
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do { \
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raw_spin_lock_irqsave_nested(spinlock_check(lock), flags, subclass); \
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} while (0)
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static __always_inline void spin_unlock(spinlock_t *lock)
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{
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raw_spin_unlock(&lock->rlock);
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}
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static __always_inline void spin_unlock_bh(spinlock_t *lock)
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{
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raw_spin_unlock_bh(&lock->rlock);
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}
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static __always_inline void spin_unlock_irq(spinlock_t *lock)
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{
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raw_spin_unlock_irq(&lock->rlock);
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}
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static __always_inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
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{
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raw_spin_unlock_irqrestore(&lock->rlock, flags);
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}
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static __always_inline int spin_trylock_bh(spinlock_t *lock)
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{
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return raw_spin_trylock_bh(&lock->rlock);
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}
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static __always_inline int spin_trylock_irq(spinlock_t *lock)
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{
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return raw_spin_trylock_irq(&lock->rlock);
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}
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#define spin_trylock_irqsave(lock, flags) \
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({ \
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raw_spin_trylock_irqsave(spinlock_check(lock), flags); \
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})
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/**
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* spin_is_locked() - Check whether a spinlock is locked.
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* @lock: Pointer to the spinlock.
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*
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* This function is NOT required to provide any memory ordering
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* guarantees; it could be used for debugging purposes or, when
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* additional synchronization is needed, accompanied with other
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* constructs (memory barriers) enforcing the synchronization.
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*
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* Returns: 1 if @lock is locked, 0 otherwise.
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*
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* Note that the function only tells you that the spinlock is
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* seen to be locked, not that it is locked on your CPU.
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*
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* Further, on CONFIG_SMP=n builds with CONFIG_DEBUG_SPINLOCK=n,
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* the return value is always 0 (see include/linux/spinlock_up.h).
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* Therefore you should not rely heavily on the return value.
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*/
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static __always_inline int spin_is_locked(spinlock_t *lock)
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{
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return raw_spin_is_locked(&lock->rlock);
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}
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static __always_inline int spin_is_contended(spinlock_t *lock)
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{
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return raw_spin_is_contended(&lock->rlock);
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}
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#define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock)
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/*
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* Pull the atomic_t declaration:
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* (asm-mips/atomic.h needs above definitions)
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*/
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#include <linux/atomic.h>
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/**
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* atomic_dec_and_lock - lock on reaching reference count zero
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* @atomic: the atomic counter
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* @lock: the spinlock in question
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*
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* Decrements @atomic by 1. If the result is 0, returns true and locks
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* @lock. Returns false for all other cases.
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*/
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extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
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#define atomic_dec_and_lock(atomic, lock) \
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__cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
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extern int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
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unsigned long *flags);
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#define atomic_dec_and_lock_irqsave(atomic, lock, flags) \
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__cond_lock(lock, _atomic_dec_and_lock_irqsave(atomic, lock, &(flags)))
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int __alloc_bucket_spinlocks(spinlock_t **locks, unsigned int *lock_mask,
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size_t max_size, unsigned int cpu_mult,
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gfp_t gfp, const char *name,
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struct lock_class_key *key);
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#define alloc_bucket_spinlocks(locks, lock_mask, max_size, cpu_mult, gfp) \
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({ \
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static struct lock_class_key key; \
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int ret; \
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\
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ret = __alloc_bucket_spinlocks(locks, lock_mask, max_size, \
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cpu_mult, gfp, #locks, &key); \
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ret; \
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})
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void free_bucket_spinlocks(spinlock_t *locks);
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#endif /* __LINUX_SPINLOCK_H */
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