10f02d1c59
In _spin_unlock_bh(lock):
do { \
_raw_spin_unlock(lock); \
preempt_enable(); \
local_bh_enable(); \
__release(lock); \
} while (0)
there is no reason for using preempt_enable() instead of a simple
preempt_enable_no_resched()
Since we know bottom halves are disabled, preempt_schedule() will always
return at once (preempt_count!=0), and hence preempt_check_resched() is
useless here...
This fixes it by using "preempt_enable_no_resched()" instead of the
"preempt_enable()", and thus avoids the useless preempt_check_resched()
just before re-enabling bottom halves.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
606 lines
16 KiB
C
606 lines
16 KiB
C
#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 locking declarations
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*/
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#include <linux/config.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/thread_info.h>
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#include <linux/kernel.h>
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#include <linux/stringify.h>
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#include <asm/processor.h> /* for cpu relax */
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#include <asm/system.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 \
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".text.lock." __stringify(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 fastcall __attribute__((section(".spinlock.text")))
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/*
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* If CONFIG_SMP is set, pull in the _raw_* definitions
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*/
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#ifdef CONFIG_SMP
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#define assert_spin_locked(x) BUG_ON(!spin_is_locked(x))
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#include <asm/spinlock.h>
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int __lockfunc _spin_trylock(spinlock_t *lock);
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int __lockfunc _read_trylock(rwlock_t *lock);
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int __lockfunc _write_trylock(rwlock_t *lock);
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void __lockfunc _spin_lock(spinlock_t *lock) __acquires(spinlock_t);
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void __lockfunc _read_lock(rwlock_t *lock) __acquires(rwlock_t);
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void __lockfunc _write_lock(rwlock_t *lock) __acquires(rwlock_t);
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void __lockfunc _spin_unlock(spinlock_t *lock) __releases(spinlock_t);
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void __lockfunc _read_unlock(rwlock_t *lock) __releases(rwlock_t);
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void __lockfunc _write_unlock(rwlock_t *lock) __releases(rwlock_t);
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unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock) __acquires(spinlock_t);
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unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock) __acquires(rwlock_t);
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unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock) __acquires(rwlock_t);
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void __lockfunc _spin_lock_irq(spinlock_t *lock) __acquires(spinlock_t);
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void __lockfunc _spin_lock_bh(spinlock_t *lock) __acquires(spinlock_t);
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void __lockfunc _read_lock_irq(rwlock_t *lock) __acquires(rwlock_t);
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void __lockfunc _read_lock_bh(rwlock_t *lock) __acquires(rwlock_t);
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void __lockfunc _write_lock_irq(rwlock_t *lock) __acquires(rwlock_t);
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void __lockfunc _write_lock_bh(rwlock_t *lock) __acquires(rwlock_t);
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void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags) __releases(spinlock_t);
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void __lockfunc _spin_unlock_irq(spinlock_t *lock) __releases(spinlock_t);
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void __lockfunc _spin_unlock_bh(spinlock_t *lock) __releases(spinlock_t);
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void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags) __releases(rwlock_t);
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void __lockfunc _read_unlock_irq(rwlock_t *lock) __releases(rwlock_t);
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void __lockfunc _read_unlock_bh(rwlock_t *lock) __releases(rwlock_t);
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void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags) __releases(rwlock_t);
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void __lockfunc _write_unlock_irq(rwlock_t *lock) __releases(rwlock_t);
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void __lockfunc _write_unlock_bh(rwlock_t *lock) __releases(rwlock_t);
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int __lockfunc _spin_trylock_bh(spinlock_t *lock);
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int __lockfunc generic_raw_read_trylock(rwlock_t *lock);
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int in_lock_functions(unsigned long addr);
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#else
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#define in_lock_functions(ADDR) 0
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#if !defined(CONFIG_PREEMPT) && !defined(CONFIG_DEBUG_SPINLOCK)
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# define _atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)
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# define ATOMIC_DEC_AND_LOCK
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#endif
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#ifdef CONFIG_DEBUG_SPINLOCK
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#define SPINLOCK_MAGIC 0x1D244B3C
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typedef struct {
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unsigned long magic;
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volatile unsigned long lock;
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volatile unsigned int babble;
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const char *module;
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char *owner;
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int oline;
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} spinlock_t;
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#define SPIN_LOCK_UNLOCKED (spinlock_t) { SPINLOCK_MAGIC, 0, 10, __FILE__ , NULL, 0}
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#define spin_lock_init(x) \
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do { \
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(x)->magic = SPINLOCK_MAGIC; \
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(x)->lock = 0; \
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(x)->babble = 5; \
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(x)->module = __FILE__; \
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(x)->owner = NULL; \
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(x)->oline = 0; \
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} while (0)
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#define CHECK_LOCK(x) \
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do { \
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if ((x)->magic != SPINLOCK_MAGIC) { \
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printk(KERN_ERR "%s:%d: spin_is_locked on uninitialized spinlock %p.\n", \
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__FILE__, __LINE__, (x)); \
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} \
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} while(0)
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#define _raw_spin_lock(x) \
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do { \
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CHECK_LOCK(x); \
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if ((x)->lock&&(x)->babble) { \
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(x)->babble--; \
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printk("%s:%d: spin_lock(%s:%p) already locked by %s/%d\n", \
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__FILE__,__LINE__, (x)->module, \
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(x), (x)->owner, (x)->oline); \
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} \
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(x)->lock = 1; \
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(x)->owner = __FILE__; \
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(x)->oline = __LINE__; \
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} while (0)
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/* without debugging, spin_is_locked on UP always says
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* FALSE. --> printk if already locked. */
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#define spin_is_locked(x) \
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({ \
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CHECK_LOCK(x); \
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if ((x)->lock&&(x)->babble) { \
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(x)->babble--; \
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printk("%s:%d: spin_is_locked(%s:%p) already locked by %s/%d\n", \
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__FILE__,__LINE__, (x)->module, \
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(x), (x)->owner, (x)->oline); \
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} \
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0; \
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})
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/* with debugging, assert_spin_locked() on UP does check
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* the lock value properly */
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#define assert_spin_locked(x) \
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({ \
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CHECK_LOCK(x); \
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BUG_ON(!(x)->lock); \
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})
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/* without debugging, spin_trylock on UP always says
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* TRUE. --> printk if already locked. */
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#define _raw_spin_trylock(x) \
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({ \
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CHECK_LOCK(x); \
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if ((x)->lock&&(x)->babble) { \
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(x)->babble--; \
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printk("%s:%d: spin_trylock(%s:%p) already locked by %s/%d\n", \
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__FILE__,__LINE__, (x)->module, \
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(x), (x)->owner, (x)->oline); \
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} \
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(x)->lock = 1; \
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(x)->owner = __FILE__; \
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(x)->oline = __LINE__; \
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1; \
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})
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#define spin_unlock_wait(x) \
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do { \
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CHECK_LOCK(x); \
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if ((x)->lock&&(x)->babble) { \
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(x)->babble--; \
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printk("%s:%d: spin_unlock_wait(%s:%p) owned by %s/%d\n", \
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__FILE__,__LINE__, (x)->module, (x), \
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(x)->owner, (x)->oline); \
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}\
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} while (0)
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#define _raw_spin_unlock(x) \
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do { \
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CHECK_LOCK(x); \
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if (!(x)->lock&&(x)->babble) { \
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(x)->babble--; \
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printk("%s:%d: spin_unlock(%s:%p) not locked\n", \
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__FILE__,__LINE__, (x)->module, (x));\
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} \
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(x)->lock = 0; \
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} while (0)
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#else
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/*
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* gcc versions before ~2.95 have a nasty bug with empty initializers.
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*/
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#if (__GNUC__ > 2)
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typedef struct { } spinlock_t;
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#define SPIN_LOCK_UNLOCKED (spinlock_t) { }
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#else
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typedef struct { int gcc_is_buggy; } spinlock_t;
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#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
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#endif
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/*
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* If CONFIG_SMP is unset, declare the _raw_* definitions as nops
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*/
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#define spin_lock_init(lock) do { (void)(lock); } while(0)
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#define _raw_spin_lock(lock) do { (void)(lock); } while(0)
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#define spin_is_locked(lock) ((void)(lock), 0)
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#define assert_spin_locked(lock) do { (void)(lock); } while(0)
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#define _raw_spin_trylock(lock) (((void)(lock), 1))
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#define spin_unlock_wait(lock) (void)(lock)
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#define _raw_spin_unlock(lock) do { (void)(lock); } while(0)
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#endif /* CONFIG_DEBUG_SPINLOCK */
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/* RW spinlocks: No debug version */
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#if (__GNUC__ > 2)
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typedef struct { } rwlock_t;
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#define RW_LOCK_UNLOCKED (rwlock_t) { }
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#else
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typedef struct { int gcc_is_buggy; } rwlock_t;
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#define RW_LOCK_UNLOCKED (rwlock_t) { 0 }
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#endif
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#define rwlock_init(lock) do { (void)(lock); } while(0)
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#define _raw_read_lock(lock) do { (void)(lock); } while(0)
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#define _raw_read_unlock(lock) do { (void)(lock); } while(0)
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#define _raw_write_lock(lock) do { (void)(lock); } while(0)
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#define _raw_write_unlock(lock) do { (void)(lock); } while(0)
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#define read_can_lock(lock) (((void)(lock), 1))
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#define write_can_lock(lock) (((void)(lock), 1))
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#define _raw_read_trylock(lock) ({ (void)(lock); (1); })
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#define _raw_write_trylock(lock) ({ (void)(lock); (1); })
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#define _spin_trylock(lock) ({preempt_disable(); _raw_spin_trylock(lock) ? \
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1 : ({preempt_enable(); 0;});})
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#define _read_trylock(lock) ({preempt_disable();_raw_read_trylock(lock) ? \
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1 : ({preempt_enable(); 0;});})
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#define _write_trylock(lock) ({preempt_disable(); _raw_write_trylock(lock) ? \
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1 : ({preempt_enable(); 0;});})
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#define _spin_trylock_bh(lock) ({preempt_disable(); local_bh_disable(); \
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_raw_spin_trylock(lock) ? \
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1 : ({preempt_enable_no_resched(); local_bh_enable(); 0;});})
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#define _spin_lock(lock) \
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do { \
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preempt_disable(); \
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_raw_spin_lock(lock); \
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__acquire(lock); \
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} while(0)
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#define _write_lock(lock) \
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do { \
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preempt_disable(); \
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_raw_write_lock(lock); \
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__acquire(lock); \
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} while(0)
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#define _read_lock(lock) \
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do { \
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preempt_disable(); \
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_raw_read_lock(lock); \
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__acquire(lock); \
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} while(0)
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#define _spin_unlock(lock) \
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do { \
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_raw_spin_unlock(lock); \
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preempt_enable(); \
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__release(lock); \
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} while (0)
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#define _write_unlock(lock) \
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do { \
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_raw_write_unlock(lock); \
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preempt_enable(); \
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__release(lock); \
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} while(0)
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#define _read_unlock(lock) \
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do { \
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_raw_read_unlock(lock); \
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preempt_enable(); \
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__release(lock); \
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} while(0)
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#define _spin_lock_irqsave(lock, flags) \
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do { \
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local_irq_save(flags); \
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preempt_disable(); \
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_raw_spin_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _spin_lock_irq(lock) \
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do { \
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local_irq_disable(); \
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preempt_disable(); \
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_raw_spin_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _spin_lock_bh(lock) \
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do { \
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local_bh_disable(); \
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preempt_disable(); \
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_raw_spin_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _read_lock_irqsave(lock, flags) \
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do { \
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local_irq_save(flags); \
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preempt_disable(); \
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_raw_read_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _read_lock_irq(lock) \
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do { \
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local_irq_disable(); \
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preempt_disable(); \
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_raw_read_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _read_lock_bh(lock) \
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do { \
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local_bh_disable(); \
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preempt_disable(); \
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_raw_read_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _write_lock_irqsave(lock, flags) \
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do { \
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local_irq_save(flags); \
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preempt_disable(); \
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_raw_write_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _write_lock_irq(lock) \
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do { \
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local_irq_disable(); \
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preempt_disable(); \
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_raw_write_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _write_lock_bh(lock) \
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do { \
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local_bh_disable(); \
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preempt_disable(); \
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_raw_write_lock(lock); \
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__acquire(lock); \
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} while (0)
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#define _spin_unlock_irqrestore(lock, flags) \
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do { \
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_raw_spin_unlock(lock); \
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local_irq_restore(flags); \
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preempt_enable(); \
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__release(lock); \
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} while (0)
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#define _spin_unlock_irq(lock) \
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do { \
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_raw_spin_unlock(lock); \
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local_irq_enable(); \
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preempt_enable(); \
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__release(lock); \
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} while (0)
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#define _spin_unlock_bh(lock) \
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do { \
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_raw_spin_unlock(lock); \
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preempt_enable_no_resched(); \
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local_bh_enable(); \
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__release(lock); \
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} while (0)
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#define _write_unlock_bh(lock) \
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do { \
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_raw_write_unlock(lock); \
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preempt_enable_no_resched(); \
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local_bh_enable(); \
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__release(lock); \
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} while (0)
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#define _read_unlock_irqrestore(lock, flags) \
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do { \
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_raw_read_unlock(lock); \
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local_irq_restore(flags); \
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preempt_enable(); \
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__release(lock); \
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} while (0)
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#define _write_unlock_irqrestore(lock, flags) \
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do { \
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_raw_write_unlock(lock); \
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local_irq_restore(flags); \
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preempt_enable(); \
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__release(lock); \
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} while (0)
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#define _read_unlock_irq(lock) \
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do { \
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_raw_read_unlock(lock); \
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local_irq_enable(); \
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preempt_enable(); \
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__release(lock); \
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} while (0)
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#define _read_unlock_bh(lock) \
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do { \
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_raw_read_unlock(lock); \
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preempt_enable_no_resched(); \
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local_bh_enable(); \
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__release(lock); \
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} while (0)
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#define _write_unlock_irq(lock) \
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do { \
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_raw_write_unlock(lock); \
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local_irq_enable(); \
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preempt_enable(); \
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__release(lock); \
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} while (0)
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#endif /* !SMP */
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/*
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* Define the various spin_lock and rw_lock methods. Note we define these
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* regardless of whether CONFIG_SMP or CONFIG_PREEMPT are set. The various
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* methods are defined as nops in the case they are not required.
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*/
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#define spin_trylock(lock) __cond_lock(_spin_trylock(lock))
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#define read_trylock(lock) __cond_lock(_read_trylock(lock))
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#define write_trylock(lock) __cond_lock(_write_trylock(lock))
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#define spin_lock(lock) _spin_lock(lock)
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#define write_lock(lock) _write_lock(lock)
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#define read_lock(lock) _read_lock(lock)
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#ifdef CONFIG_SMP
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#define spin_lock_irqsave(lock, flags) flags = _spin_lock_irqsave(lock)
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#define read_lock_irqsave(lock, flags) flags = _read_lock_irqsave(lock)
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#define write_lock_irqsave(lock, flags) flags = _write_lock_irqsave(lock)
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#else
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#define spin_lock_irqsave(lock, flags) _spin_lock_irqsave(lock, flags)
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#define read_lock_irqsave(lock, flags) _read_lock_irqsave(lock, flags)
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#define write_lock_irqsave(lock, flags) _write_lock_irqsave(lock, flags)
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#endif
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#define spin_lock_irq(lock) _spin_lock_irq(lock)
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#define spin_lock_bh(lock) _spin_lock_bh(lock)
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#define read_lock_irq(lock) _read_lock_irq(lock)
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#define read_lock_bh(lock) _read_lock_bh(lock)
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#define write_lock_irq(lock) _write_lock_irq(lock)
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#define write_lock_bh(lock) _write_lock_bh(lock)
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#define spin_unlock(lock) _spin_unlock(lock)
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#define write_unlock(lock) _write_unlock(lock)
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#define read_unlock(lock) _read_unlock(lock)
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#define spin_unlock_irqrestore(lock, flags) _spin_unlock_irqrestore(lock, flags)
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#define spin_unlock_irq(lock) _spin_unlock_irq(lock)
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#define spin_unlock_bh(lock) _spin_unlock_bh(lock)
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#define read_unlock_irqrestore(lock, flags) _read_unlock_irqrestore(lock, flags)
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#define read_unlock_irq(lock) _read_unlock_irq(lock)
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#define read_unlock_bh(lock) _read_unlock_bh(lock)
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#define write_unlock_irqrestore(lock, flags) _write_unlock_irqrestore(lock, flags)
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#define write_unlock_irq(lock) _write_unlock_irq(lock)
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#define write_unlock_bh(lock) _write_unlock_bh(lock)
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#define spin_trylock_bh(lock) __cond_lock(_spin_trylock_bh(lock))
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#define spin_trylock_irq(lock) \
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({ \
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local_irq_disable(); \
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_spin_trylock(lock) ? \
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1 : ({local_irq_enable(); 0; }); \
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})
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#define spin_trylock_irqsave(lock, flags) \
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({ \
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local_irq_save(flags); \
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_spin_trylock(lock) ? \
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1 : ({local_irq_restore(flags); 0;}); \
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})
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#ifdef CONFIG_LOCKMETER
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extern void _metered_spin_lock (spinlock_t *lock);
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extern void _metered_spin_unlock (spinlock_t *lock);
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extern int _metered_spin_trylock(spinlock_t *lock);
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extern void _metered_read_lock (rwlock_t *lock);
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extern void _metered_read_unlock (rwlock_t *lock);
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extern void _metered_write_lock (rwlock_t *lock);
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extern void _metered_write_unlock (rwlock_t *lock);
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extern int _metered_read_trylock (rwlock_t *lock);
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extern int _metered_write_trylock(rwlock_t *lock);
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#endif
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|
/* "lock on reference count zero" */
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#ifndef ATOMIC_DEC_AND_LOCK
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#include <asm/atomic.h>
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extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
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#endif
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|
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#define atomic_dec_and_lock(atomic,lock) __cond_lock(_atomic_dec_and_lock(atomic,lock))
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|
|
|
/*
|
|
* bit-based spin_lock()
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|
*
|
|
* Don't use this unless you really need to: spin_lock() and spin_unlock()
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|
* are significantly faster.
|
|
*/
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|
static inline void bit_spin_lock(int bitnum, unsigned long *addr)
|
|
{
|
|
/*
|
|
* Assuming the lock is uncontended, this never enters
|
|
* the body of the outer loop. If it is contended, then
|
|
* within the inner loop a non-atomic test is used to
|
|
* busywait with less bus contention for a good time to
|
|
* attempt to acquire the lock bit.
|
|
*/
|
|
preempt_disable();
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
while (test_and_set_bit(bitnum, addr)) {
|
|
while (test_bit(bitnum, addr)) {
|
|
preempt_enable();
|
|
cpu_relax();
|
|
preempt_disable();
|
|
}
|
|
}
|
|
#endif
|
|
__acquire(bitlock);
|
|
}
|
|
|
|
/*
|
|
* Return true if it was acquired
|
|
*/
|
|
static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
|
|
{
|
|
preempt_disable();
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
if (test_and_set_bit(bitnum, addr)) {
|
|
preempt_enable();
|
|
return 0;
|
|
}
|
|
#endif
|
|
__acquire(bitlock);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* bit-based spin_unlock()
|
|
*/
|
|
static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
|
|
{
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
BUG_ON(!test_bit(bitnum, addr));
|
|
smp_mb__before_clear_bit();
|
|
clear_bit(bitnum, addr);
|
|
#endif
|
|
preempt_enable();
|
|
__release(bitlock);
|
|
}
|
|
|
|
/*
|
|
* Return true if the lock is held.
|
|
*/
|
|
static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
|
|
{
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
|
|
return test_bit(bitnum, addr);
|
|
#elif defined CONFIG_PREEMPT
|
|
return preempt_count();
|
|
#else
|
|
return 1;
|
|
#endif
|
|
}
|
|
|
|
#define DEFINE_SPINLOCK(x) spinlock_t x = SPIN_LOCK_UNLOCKED
|
|
#define DEFINE_RWLOCK(x) rwlock_t x = RW_LOCK_UNLOCKED
|
|
|
|
/**
|
|
* spin_can_lock - would spin_trylock() succeed?
|
|
* @lock: the spinlock in question.
|
|
*/
|
|
#define spin_can_lock(lock) (!spin_is_locked(lock))
|
|
|
|
#endif /* __LINUX_SPINLOCK_H */
|