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496 lines
14 KiB
496 lines
14 KiB
/* 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 <linux/lockdep.h> |
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#include <asm/barrier.h> |
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#include <asm/mmiowb.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 __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, short inner); |
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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, LD_WAIT_SPIN); \ |
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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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mmiowb_spin_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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mmiowb_spin_lock(); |
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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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int ret = arch_spin_trylock(&(lock)->raw_lock); |
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if (ret) |
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mmiowb_spin_lock(); |
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return ret; |
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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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mmiowb_spin_unlock(); |
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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_PREEMPTION 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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#ifdef CONFIG_DEBUG_SPINLOCK |
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# define 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(spinlock_check(lock), \ |
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#lock, &__key, LD_WAIT_CONFIG); \ |
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} while (0) |
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#else |
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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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*(_lock) = __SPIN_LOCK_UNLOCKED(_lock); \ |
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} while (0) |
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#endif |
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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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