0,0 → 1,163 |
/* |
* Copyright (C) 2001-2004 Jakub Jermar |
* All rights reserved. |
* |
* Redistribution and use in source and binary forms, with or without |
* modification, are permitted provided that the following conditions |
* are met: |
* |
* - Redistributions of source code must retain the above copyright |
* notice, this list of conditions and the following disclaimer. |
* - Redistributions in binary form must reproduce the above copyright |
* notice, this list of conditions and the following disclaimer in the |
* documentation and/or other materials provided with the distribution. |
* - The name of the author may not be used to endorse or promote products |
* derived from this software without specific prior written permission. |
* |
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
*/ |
|
/** @addtogroup sync |
* @{ |
*/ |
|
/** |
* @file |
* @brief Spinlocks. |
*/ |
|
#include <synch/spinlock.h> |
#include <atomic.h> |
#include <arch/barrier.h> |
#include <arch.h> |
#include <preemption.h> |
#include <print.h> |
#include <debug.h> |
#include <symtab.h> |
|
#ifdef CONFIG_FB |
#include <genarch/fb/fb.h> |
#endif |
|
#ifdef CONFIG_SMP |
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/** Initialize spinlock |
* |
* Initialize spinlock. |
* |
* @param sl Pointer to spinlock_t structure. |
*/ |
void spinlock_initialize(spinlock_t *sl, char *name) |
{ |
atomic_set(&sl->val, 0); |
#ifdef CONFIG_DEBUG_SPINLOCK |
sl->name = name; |
#endif |
} |
|
/** Lock spinlock |
* |
* Lock spinlock. |
* This version has limitted ability to report |
* possible occurence of deadlock. |
* |
* @param sl Pointer to spinlock_t structure. |
*/ |
#ifdef CONFIG_DEBUG_SPINLOCK |
#define DEADLOCK_THRESHOLD 100000000 |
void spinlock_lock_debug(spinlock_t *sl) |
{ |
count_t i = 0; |
char *symbol; |
bool deadlock_reported = false; |
|
preemption_disable(); |
while (test_and_set(&sl->val)) { |
|
/* |
* We need to be careful about printflock and fb_lock. |
* Both of them are used to report deadlocks via |
* printf() and fb_putchar(). |
* |
* We trust our code that there is no possible deadlock |
* caused by these two locks (except when an exception |
* is triggered for instance by printf() or fb_putchar()). |
* However, we encountered false positives caused by very |
* slow VESA framebuffer interaction (especially when |
* run in a simulator) that caused problems with both |
* printflock and fb_lock. |
* |
* Possible deadlocks on both printflock and fb_lock |
* are therefore not reported as they would cause an |
* infinite recursion. |
*/ |
if (sl == &printflock) |
continue; |
#ifdef CONFIG_FB |
if (sl == &fb_lock) |
continue; |
#endif |
if (i++ > DEADLOCK_THRESHOLD) { |
printf("cpu%d: looping on spinlock %.*p:%s, caller=%.*p", |
CPU->id, sizeof(__address) * 2, sl, sl->name, sizeof(__address) * 2, CALLER); |
symbol = get_symtab_entry(CALLER); |
if (symbol) |
printf("(%s)", symbol); |
printf("\n"); |
i = 0; |
deadlock_reported = true; |
} |
} |
|
if (deadlock_reported) |
printf("cpu%d: not deadlocked\n", CPU->id); |
|
/* |
* Prevent critical section code from bleeding out this way up. |
*/ |
CS_ENTER_BARRIER(); |
} |
#endif |
|
/** Lock spinlock conditionally |
* |
* Lock spinlock conditionally. |
* If the spinlock is not available at the moment, |
* signal failure. |
* |
* @param sl Pointer to spinlock_t structure. |
* |
* @return Zero on failure, non-zero otherwise. |
*/ |
int spinlock_trylock(spinlock_t *sl) |
{ |
int rc; |
|
preemption_disable(); |
rc = !test_and_set(&sl->val); |
|
/* |
* Prevent critical section code from bleeding out this way up. |
*/ |
CS_ENTER_BARRIER(); |
|
if (!rc) |
preemption_enable(); |
|
return rc; |
} |
|
#endif |
|
/** @} |
*/ |
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