533d396761
Any number of readers may be in the critical section at a time and writers are mutually exclusive to all other threads. They are a better choice when data is rarely modified but often read and multiple threads can safely access it for reading. Priority inheritance is fully implemented along with other changes to the kernel to fully support it on multiowner objects. This also cleans up priority code in the kernel and updates some associated structures in existing objects to the cleaner form. Currently doesn't add the mrsw_lock.[ch] files since they're not yet needed by anything but the supporting improvements are still useful. This includes a typed bitarray API (bitarray.h) which is pretty basic for now. Change-Id: Idbe43dcd9170358e06d48d00f1c69728ff45b0e3 Reviewed-on: http://gerrit.rockbox.org/801 Reviewed-by: Michael Sevakis <jethead71@rockbox.org> Tested: Michael Sevakis <jethead71@rockbox.org>
56 lines
2.1 KiB
C
56 lines
2.1 KiB
C
/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2002 by Björn Stenberg
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#ifndef MUTEX_H
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#define MUTEX_H
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#include <stdbool.h>
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#include "config.h"
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#include "thread.h"
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struct mutex
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{
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struct thread_entry *queue; /* waiter list */
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int recursion; /* lock owner recursion count */
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struct blocker blocker; /* priority inheritance info
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for waiters and owner*/
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IF_COP( struct corelock cl; ) /* multiprocessor sync */
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#ifdef HAVE_PRIORITY_SCHEDULING
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bool no_preempt;
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#endif
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};
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extern void mutex_init(struct mutex *m);
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extern void mutex_lock(struct mutex *m);
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extern void mutex_unlock(struct mutex *m);
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#ifdef HAVE_PRIORITY_SCHEDULING
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/* Deprecated temporary function to disable mutex preempting a thread on
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* unlock - firmware/drivers/fat.c and a couple places in apps/buffering.c -
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* reliance on it is a bug! */
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static inline void mutex_set_preempt(struct mutex *m, bool preempt)
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{ m->no_preempt = !preempt; }
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#else
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/* Deprecated but needed for now - firmware/drivers/ata_mmc.c */
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static inline bool mutex_test(const struct mutex *m)
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{ return m->blocker.thread != NULL; }
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#endif /* HAVE_PRIORITY_SCHEDULING */
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#endif /* MUTEX_H */
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