diff options
| -rw-r--r-- | drivers/acpi/osl.c | 89 | ||||
| -rw-r--r-- | include/linux/semaphore.h | 6 | ||||
| -rw-r--r-- | kernel/semaphore.c | 42 |
3 files changed, 62 insertions, 75 deletions
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index a697fb6..a498a6c 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -4,6 +4,8 @@ * Copyright (C) 2000 Andrew Henroid * Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com> * Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com> + * Copyright (c) 2008 Intel Corporation + * Author: Matthew Wilcox <willy@linux.intel.com> * * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * @@ -37,15 +39,18 @@ #include <linux/workqueue.h> #include <linux/nmi.h> #include <linux/acpi.h> -#include <acpi/acpi.h> -#include <asm/io.h> -#include <acpi/acpi_bus.h> -#include <acpi/processor.h> -#include <asm/uaccess.h> - #include <linux/efi.h> #include <linux/ioport.h> #include <linux/list.h> +#include <linux/jiffies.h> +#include <linux/semaphore.h> + +#include <asm/io.h> +#include <asm/uaccess.h> + +#include <acpi/acpi.h> +#include <acpi/acpi_bus.h> +#include <acpi/processor.h> #define _COMPONENT ACPI_OS_SERVICES ACPI_MODULE_NAME("osl"); @@ -764,7 +769,6 @@ acpi_os_create_semaphore(u32 max_units, u32 initial_units, acpi_handle * handle) { struct semaphore *sem = NULL; - sem = acpi_os_allocate(sizeof(struct semaphore)); if (!sem) return AE_NO_MEMORY; @@ -791,12 +795,12 @@ acpi_status acpi_os_delete_semaphore(acpi_handle handle) { struct semaphore *sem = (struct semaphore *)handle; - if (!sem) return AE_BAD_PARAMETER; ACPI_DEBUG_PRINT((ACPI_DB_MUTEX, "Deleting semaphore[%p].\n", handle)); + BUG_ON(!list_empty(&sem->wait_list)); kfree(sem); sem = NULL; @@ -804,21 +808,15 @@ acpi_status acpi_os_delete_semaphore(acpi_handle handle) } /* - * TODO: The kernel doesn't have a 'down_timeout' function -- had to - * improvise. The process is to sleep for one scheduler quantum - * until the semaphore becomes available. Downside is that this - * may result in starvation for timeout-based waits when there's - * lots of semaphore activity. - * * TODO: Support for units > 1? */ acpi_status acpi_os_wait_semaphore(acpi_handle handle, u32 units, u16 timeout) { acpi_status status = AE_OK; struct semaphore *sem = (struct semaphore *)handle; + long jiffies; int ret = 0; - if (!sem || (units < 1)) return AE_BAD_PARAMETER; @@ -828,58 +826,14 @@ acpi_status acpi_os_wait_semaphore(acpi_handle handle, u32 units, u16 timeout) ACPI_DEBUG_PRINT((ACPI_DB_MUTEX, "Waiting for semaphore[%p|%d|%d]\n", handle, units, timeout)); - /* - * This can be called during resume with interrupts off. - * Like boot-time, we should be single threaded and will - * always get the lock if we try -- timeout or not. - * If this doesn't succeed, then we will oops courtesy of - * might_sleep() in down(). - */ - if (!down_trylock(sem)) - return AE_OK; - - switch (timeout) { - /* - * No Wait: - * -------- - * A zero timeout value indicates that we shouldn't wait - just - * acquire the semaphore if available otherwise return AE_TIME - * (a.k.a. 'would block'). - */ - case 0: - if (down_trylock(sem)) - status = AE_TIME; - break; - - /* - * Wait Indefinitely: - * ------------------ - */ - case ACPI_WAIT_FOREVER: - down(sem); - break; - - /* - * Wait w/ Timeout: - * ---------------- - */ - default: - // TODO: A better timeout algorithm? - { - int i = 0; - static const int quantum_ms = 1000 / HZ; - - ret = down_trylock(sem); - for (i = timeout; (i > 0 && ret != 0); i -= quantum_ms) { - schedule_timeout_interruptible(1); - ret = down_trylock(sem); - } - - if (ret != 0) - status = AE_TIME; - } - break; - } + if (timeout == ACPI_WAIT_FOREVER) + jiffies = MAX_SCHEDULE_TIMEOUT; + else + jiffies = msecs_to_jiffies(timeout); + + ret = down_timeout(sem, jiffies); + if (ret) + status = AE_TIME; if (ACPI_FAILURE(status)) { ACPI_DEBUG_PRINT((ACPI_DB_MUTEX, @@ -902,7 +856,6 @@ acpi_status acpi_os_signal_semaphore(acpi_handle handle, u32 units) { struct semaphore *sem = (struct semaphore *)handle; - if (!sem || (units < 1)) return AE_BAD_PARAMETER; diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h index 88f2a28..a107aeb 100644 --- a/include/linux/semaphore.h +++ b/include/linux/semaphore.h @@ -75,6 +75,12 @@ extern int __must_check down_killable(struct semaphore *sem); extern int __must_check down_trylock(struct semaphore *sem); /* + * As down(), except this function will return -ETIME if it fails to + * acquire the semaphore within the specified number of jiffies. + */ +extern int __must_check down_timeout(struct semaphore *sem, long jiffies); + +/* * Release the semaphore. Unlike mutexes, up() may be called from any * context and even by tasks which have never called down(). */ diff --git a/kernel/semaphore.c b/kernel/semaphore.c index 2da2aed..5a12a85 100644 --- a/kernel/semaphore.c +++ b/kernel/semaphore.c @@ -35,6 +35,7 @@ static noinline void __down(struct semaphore *sem); static noinline int __down_interruptible(struct semaphore *sem); static noinline int __down_killable(struct semaphore *sem); +static noinline int __down_timeout(struct semaphore *sem, long jiffies); static noinline void __up(struct semaphore *sem); void down(struct semaphore *sem) @@ -104,6 +105,20 @@ int down_trylock(struct semaphore *sem) } EXPORT_SYMBOL(down_trylock); +int down_timeout(struct semaphore *sem, long jiffies) +{ + unsigned long flags; + int result = 0; + + spin_lock_irqsave(&sem->lock, flags); + if (unlikely(sem->count-- <= 0)) + result = __down_timeout(sem, jiffies); + spin_unlock_irqrestore(&sem->lock, flags); + + return result; +} +EXPORT_SYMBOL(down_timeout); + void up(struct semaphore *sem) { unsigned long flags; @@ -142,10 +157,12 @@ static noinline void __sched __up_down_common(struct semaphore *sem) } /* - * Because this function is inlined, the 'state' parameter will be constant, - * and thus optimised away by the compiler. + * Because this function is inlined, the 'state' parameter will be + * constant, and thus optimised away by the compiler. Likewise the + * 'timeout' parameter for the cases without timeouts. */ -static inline int __sched __down_common(struct semaphore *sem, long state) +static inline int __sched __down_common(struct semaphore *sem, long state, + long timeout) { int result = 0; struct task_struct *task = current; @@ -160,14 +177,20 @@ static inline int __sched __down_common(struct semaphore *sem, long state) goto interrupted; if (state == TASK_KILLABLE && fatal_signal_pending(task)) goto interrupted; + if (timeout <= 0) + goto timed_out; __set_task_state(task, state); spin_unlock_irq(&sem->lock); - schedule(); + timeout = schedule_timeout(timeout); spin_lock_irq(&sem->lock); if (waiter.up) goto woken; } + timed_out: + list_del(&waiter.list); + result = -ETIME; + goto woken; interrupted: list_del(&waiter.list); result = -EINTR; @@ -187,17 +210,22 @@ static inline int __sched __down_common(struct semaphore *sem, long state) static noinline void __sched __down(struct semaphore *sem) { - __down_common(sem, TASK_UNINTERRUPTIBLE); + __down_common(sem, TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); } static noinline int __sched __down_interruptible(struct semaphore *sem) { - return __down_common(sem, TASK_INTERRUPTIBLE); + return __down_common(sem, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); } static noinline int __sched __down_killable(struct semaphore *sem) { - return __down_common(sem, TASK_KILLABLE); + return __down_common(sem, TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT); +} + +static noinline int __sched __down_timeout(struct semaphore *sem, long jiffies) +{ + return __down_common(sem, TASK_UNINTERRUPTIBLE, jiffies); } static noinline void __sched __up(struct semaphore *sem) |
