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* locking, semaphores: Annotate inner lock as rawThomas Gleixner2011-09-131-2/+2
| | | | | | | | | | | | | | | There is no reason to have the spin_lock protecting the semaphore preemptible on -rt. Annotate it as a raw_spinlock. In mainline this change documents the low level nature of the lock - otherwise there's no functional difference. Lockdep and Sparse checking will work as usual. ( On rt this also solves lockdep complaining about the rt_mutex.wait_lock being not initialized. ) Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* semaphore: Remove mutex emulationThomas Gleixner2010-10-301-6/+0
| | | | | | | | | | | | Semaphores used as mutexes have been deprecated for years. Now that all users are either converted to real semaphores or to mutexes remove the cruft. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Christoph Hellwig <hch@infradead.org> LKML-Reference: <20100907125057.562399240@linutronix.de>
* semaphore: Add DEFINE_SEMAPHOREThomas Gleixner2010-09-081-0/+3
| | | | | | | | | | | | | | | The full cleanup of init_MUTEX[_LOCKED] and DECLARE_MUTEX has not been done. Some of the users are real semaphores and we should name them as such instead of confusing everyone with "MUTEX". Provide the infrastructure to get finally rid of init_MUTEX[_LOCKED] and DECLARE_MUTEX. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Christoph Hellwig <hch@infradead.org> LKML-Reference: <20100907125054.795929962@linutronix.de>
* Remove __DECLARE_SEMAPHORE_GENERICMatthew Wilcox2008-07-241-4/+2
| | | | | | There are no users of __DECLARE_SEMAPHORE_GENERIC in the kernel Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
* Improve semaphore documentationMatthew Wilcox2008-04-171-37/+2
| | | | | | | | Move documentation from semaphore.h to semaphore.c as requested by Andrew Morton. Also reformat to kernel-doc style and add some more notes about the implementation. Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
* Simplify semaphore implementationMatthew Wilcox2008-04-171-6/+3
| | | | | | | | | By removing the negative values of 'count' and relying on the wait_list to indicate whether we have any waiters, we can simplify the implementation by removing the protection against an unlikely race condition. Thanks to David Howells for his suggestions. Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
* Add down_timeout and change ACPI to use itMatthew Wilcox2008-04-171-0/+6
| | | | | | | | | ACPI currently emulates a timeout for semaphores with calls to down_trylock and sleep. This produces horrible behaviour in terms of fairness and excessive wakeups. Now that we have a unified semaphore implementation, adding a real down_trylock is almost trivial. Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
* Introduce down_killable()Matthew Wilcox2008-04-171-0/+6
| | | | | | down_killable() is the functional counterpart of mutex_lock_killable. Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
* Generic semaphore implementationMatthew Wilcox2008-04-171-0/+77
Semaphores are no longer performance-critical, so a generic C implementation is better for maintainability, debuggability and extensibility. Thanks to Peter Zijlstra for fixing the lockdep warning. Thanks to Harvey Harrison for pointing out that the unlikely() was unnecessary. Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Acked-by: Ingo Molnar <mingo@elte.hu>
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