diff options
Diffstat (limited to 'arch/i386/kernel/semaphore.c')
| -rw-r--r-- | arch/i386/kernel/semaphore.c | 285 |
1 files changed, 0 insertions, 285 deletions
diff --git a/arch/i386/kernel/semaphore.c b/arch/i386/kernel/semaphore.c index 82664365aa85..338c6d7e3c3d 100644 --- a/arch/i386/kernel/semaphore.c +++ b/arch/i386/kernel/semaphore.c @@ -233,291 +233,6 @@ asm( "ret" ); -asm( -" -.text -.align 4 -.globl __down_read_failed -__down_read_failed: - pushl %edx - pushl %ecx - call down_read_failed - popl %ecx - popl %edx - ret -" -); - -asm( -" -.text -.align 4 -.globl __down_write_failed -__down_write_failed: - pushl %edx - pushl %ecx - call down_write_failed - popl %ecx - popl %edx - ret -" -); - -asm( -" -.text -.align 4 -.globl __rwsem_wake -__rwsem_wake: - pushl %edx - pushl %ecx - call rwsem_wake - popl %ecx - popl %edx - ret -" -); - -struct rw_semaphore *FASTCALL(rwsem_wake(struct rw_semaphore *sem)); -struct rw_semaphore *FASTCALL(down_read_failed(struct rw_semaphore *sem)); -struct rw_semaphore *FASTCALL(down_write_failed(struct rw_semaphore *sem)); - -/* - * implement exchange and add functionality - */ -static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem) -{ - int tmp = delta; - -#ifndef CONFIG_USING_SPINLOCK_BASED_RWSEM - __asm__ __volatile__( - LOCK_PREFIX "xadd %0,(%1)" - : "+r"(tmp) - : "r"(sem) - : "memory"); - -#else - - __asm__ __volatile__( - "# beginning rwsem_atomic_update\n\t" -#ifdef CONFIG_SMP -LOCK_PREFIX " decb "RWSEM_SPINLOCK_OFFSET_STR"(%1)\n\t" /* try to grab the spinlock */ - " js 3f\n" /* jump if failed */ - "1:\n\t" -#endif - " xchgl %0,(%1)\n\t" /* retrieve the old value */ - " addl %0,(%1)\n\t" /* add 0xffff0001, result in memory */ -#ifdef CONFIG_SMP - " movb $1,"RWSEM_SPINLOCK_OFFSET_STR"(%1)\n\t" /* release the spinlock */ -#endif - ".section .text.lock,\"ax\"\n" -#ifdef CONFIG_SMP - "3:\n\t" /* spin on the spinlock till we get it */ - " cmpb $0,"RWSEM_SPINLOCK_OFFSET_STR"(%1)\n\t" - " rep;nop \n\t" - " jle 3b\n\t" - " jmp 1b\n" -#endif - ".previous\n" - "# ending rwsem_atomic_update\n\t" - : "+r"(tmp) - : "r"(sem) - : "memory"); - -#endif - return tmp+delta; -} - -/* - * implement compare and exchange functionality on the rw-semaphore count LSW - */ -static inline __u16 rwsem_cmpxchgw(struct rw_semaphore *sem, __u16 old, __u16 new) -{ -#ifndef CONFIG_USING_SPINLOCK_BASED_RWSEM - return cmpxchg((__u16*)&sem->count.counter,0,RWSEM_ACTIVE_BIAS); - -#else - __u16 prev; - - __asm__ __volatile__( - "# beginning rwsem_cmpxchgw\n\t" -#ifdef CONFIG_SMP -LOCK_PREFIX " decb "RWSEM_SPINLOCK_OFFSET_STR"(%3)\n\t" /* try to grab the spinlock */ - " js 3f\n" /* jump if failed */ - "1:\n\t" -#endif - " cmpw %w1,(%3)\n\t" - " jne 4f\n\t" /* jump if old doesn't match sem->count LSW */ - " movw %w2,(%3)\n\t" /* replace sem->count LSW with the new value */ - "2:\n\t" -#ifdef CONFIG_SMP - " movb $1,"RWSEM_SPINLOCK_OFFSET_STR"(%3)\n\t" /* release the spinlock */ -#endif - ".section .text.lock,\"ax\"\n" -#ifdef CONFIG_SMP - "3:\n\t" /* spin on the spinlock till we get it */ - " cmpb $0,"RWSEM_SPINLOCK_OFFSET_STR"(%3)\n\t" - " rep;nop \n\t" - " jle 3b\n\t" - " jmp 1b\n" -#endif - "4:\n\t" - " movw (%3),%w0\n" /* we'll want to return the current value */ - " jmp 2b\n" - ".previous\n" - "# ending rwsem_cmpxchgw\n\t" - : "=r"(prev) - : "r0"(old), "r"(new), "r"(sem) - : "memory"); - - return prev; -#endif -} - -/* - * wait for the read lock to be granted - * - need to repeal the increment made inline by the caller - * - need to throw a write-lock style spanner into the works (sub 0x00010000 from count) - */ -struct rw_semaphore *down_read_failed(struct rw_semaphore *sem) -{ - struct task_struct *tsk = current; - DECLARE_WAITQUEUE(wait,tsk); - int count; - - rwsemdebug("[%d] Entering down_read_failed(%08x)\n",current->pid,atomic_read(&sem->count)); - - /* this waitqueue context flag will be cleared when we are granted the lock */ - __set_bit(RWSEM_WAITING_FOR_READ,&wait.flags); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - - add_wait_queue_exclusive(&sem->wait, &wait); /* FIFO */ - - /* note that we're now waiting on the lock, but no longer actively read-locking */ - count = rwsem_atomic_update(RWSEM_WAITING_BIAS-RWSEM_ACTIVE_BIAS,sem); - rwsemdebug("X(%08x)\n",count); - - /* if there are no longer active locks, wake the front queued process(es) up - * - it might even be this process, since the waker takes a more active part - */ - if (!(count & RWSEM_ACTIVE_MASK)) - rwsem_wake(sem); - - /* wait to be given the lock */ - for (;;) { - if (!test_bit(RWSEM_WAITING_FOR_READ,&wait.flags)) - break; - schedule(); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - } - - remove_wait_queue(&sem->wait,&wait); - tsk->state = TASK_RUNNING; - - rwsemdebug("[%d] Leaving down_read_failed(%08x)\n",current->pid,atomic_read(&sem->count)); - - return sem; -} - -/* - * wait for the write lock to be granted - */ -struct rw_semaphore *down_write_failed(struct rw_semaphore *sem) -{ - struct task_struct *tsk = current; - DECLARE_WAITQUEUE(wait,tsk); - int count; - - rwsemdebug("[%d] Entering down_write_failed(%08x)\n", - current->pid,atomic_read(&sem->count)); - - /* this waitqueue context flag will be cleared when we are granted the lock */ - __set_bit(RWSEM_WAITING_FOR_WRITE,&wait.flags); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - - add_wait_queue_exclusive(&sem->wait, &wait); /* FIFO */ - - /* note that we're waiting on the lock, but no longer actively locking */ - count = rwsem_atomic_update(-RWSEM_ACTIVE_BIAS,sem); - rwsemdebug("[%d] updated(%08x)\n",current->pid,count); - - /* if there are no longer active locks, wake the front queued process(es) up - * - it might even be this process, since the waker takes a more active part - */ - if (!(count & RWSEM_ACTIVE_MASK)) - rwsem_wake(sem); - - /* wait to be given the lock */ - for (;;) { - if (!test_bit(RWSEM_WAITING_FOR_WRITE,&wait.flags)) - break; - schedule(); - set_task_state(tsk, TASK_UNINTERRUPTIBLE); - } - - remove_wait_queue(&sem->wait,&wait); - tsk->state = TASK_RUNNING; - - rwsemdebug("[%d] Leaving down_write_failed(%08x)\n",current->pid,atomic_read(&sem->count)); - - return sem; -} - -/* - * handle the lock being released whilst there are processes blocked on it that can now run - * - if we come here, then: - * - the 'active part' of the count (&0x0000ffff) reached zero (but may no longer be zero) - * - the 'waiting part' of the count (&0xffff0000) is negative (and will still be so) - */ -struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem) -{ - int woken, count; - - rwsemdebug("[%d] Entering rwsem_wake(%08x)\n",current->pid,atomic_read(&sem->count)); - - try_again: - /* try to grab an 'activity' marker - * - need to make sure two copies of rwsem_wake() don't do this for two separate processes - * simultaneously - * - be horribly naughty, and only deal with the LSW of the atomic counter - */ - if (rwsem_cmpxchgw(sem,0,RWSEM_ACTIVE_BIAS)!=0) { - rwsemdebug("[%d] rwsem_wake: abort wakeup due to renewed activity\n",current->pid); - goto out; - } - - /* try to grant a single write lock if there's a writer at the front of the queue - * - note we leave the 'active part' of the count incremented by 1 and the waiting part - * incremented by 0x00010000 - */ - if (wake_up_ctx(&sem->wait,1,-RWSEM_WAITING_FOR_WRITE)==1) - goto out; - - /* grant an infinite number of read locks to the readers at the front of the queue - * - note we increment the 'active part' of the count by the number of readers just woken, - * less one for the activity decrement we've already done - */ - woken = wake_up_ctx(&sem->wait,65535,-RWSEM_WAITING_FOR_READ); - if (woken<=0) - goto counter_correction; - - woken *= RWSEM_ACTIVE_BIAS-RWSEM_WAITING_BIAS; - woken -= RWSEM_ACTIVE_BIAS; - rwsem_atomic_update(woken,sem); - - out: - rwsemdebug("[%d] Leaving rwsem_wake(%08x)\n",current->pid,atomic_read(&sem->count)); - return sem; - - /* come here if we need to correct the counter for odd SMP-isms */ - counter_correction: - count = rwsem_atomic_update(-RWSEM_ACTIVE_BIAS,sem); - rwsemdebug("[%d] corrected(%08x)\n",current->pid,count); - if (!(count & RWSEM_ACTIVE_MASK)) - goto try_again; - goto out; -} - /* * rw spinlock fallbacks */ |