| 0,0 → 1,161 |
|---|
| /* |
| * 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 |
| |
| /** 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 |
| 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 printf_lock 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 |
| * printf_lock and fb_lock. |
| * |
| * Possible deadlocks on both printf_lock and fb_lock |
| * are therefore not reported as they would cause an |
| * infinite recursion. |
| */ |
| if (sl == &printf_lock) |
| continue; |
| #ifdef CONFIG_FB |
| if (sl == &fb_lock) |
| continue; |
| #endif |
| if (i++ > DEADLOCK_THRESHOLD) { |
| printf("cpu%u: looping on spinlock %" PRIp ":%s, caller=%" PRIp, |
| CPU->id, sl, sl->name, CALLER); |
| symbol = get_symtab_entry(CALLER); |
| if (symbol) |
| printf("(%s)", symbol); |
| printf("\n"); |
| i = 0; |
| deadlock_reported = true; |
| } |
| } |
| |
| if (deadlock_reported) |
| printf("cpu%u: 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 |
| |
| /** @} |
| */ |