coroutines: Locks

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2011-06-30 17:56:46 +02:00
parent f9f05dc58c
commit b96e92470a
5 changed files with 198 additions and 1 deletions

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@ -12,7 +12,7 @@ oslib-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o
#######################################################################
# coroutines
coroutine-obj-y = qemu-coroutine.o
coroutine-obj-y = qemu-coroutine.o qemu-coroutine-lock.o
ifeq ($(CONFIG_UCONTEXT_COROUTINE),y)
coroutine-obj-$(CONFIG_POSIX) += coroutine-ucontext.o
else

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@ -38,6 +38,7 @@ struct Coroutine {
void *entry_arg;
Coroutine *caller;
QLIST_ENTRY(Coroutine) pool_next;
QTAILQ_ENTRY(Coroutine) co_queue_next;
};
Coroutine *qemu_coroutine_new(void);

124
qemu-coroutine-lock.c Normal file
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@ -0,0 +1,124 @@
/*
* coroutine queues and locks
*
* Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu-common.h"
#include "qemu-coroutine.h"
#include "qemu-coroutine-int.h"
#include "qemu-queue.h"
#include "trace.h"
static QTAILQ_HEAD(, Coroutine) unlock_bh_queue =
QTAILQ_HEAD_INITIALIZER(unlock_bh_queue);
struct unlock_bh {
QEMUBH *bh;
};
static void qemu_co_queue_next_bh(void *opaque)
{
struct unlock_bh *unlock_bh = opaque;
Coroutine *next;
trace_qemu_co_queue_next_bh();
while ((next = QTAILQ_FIRST(&unlock_bh_queue))) {
QTAILQ_REMOVE(&unlock_bh_queue, next, co_queue_next);
qemu_coroutine_enter(next, NULL);
}
qemu_bh_delete(unlock_bh->bh);
qemu_free(unlock_bh);
}
void qemu_co_queue_init(CoQueue *queue)
{
QTAILQ_INIT(&queue->entries);
}
void coroutine_fn qemu_co_queue_wait(CoQueue *queue)
{
Coroutine *self = qemu_coroutine_self();
QTAILQ_INSERT_TAIL(&queue->entries, self, co_queue_next);
qemu_coroutine_yield();
assert(qemu_in_coroutine());
}
bool qemu_co_queue_next(CoQueue *queue)
{
struct unlock_bh *unlock_bh;
Coroutine *next;
next = QTAILQ_FIRST(&queue->entries);
if (next) {
QTAILQ_REMOVE(&queue->entries, next, co_queue_next);
QTAILQ_INSERT_TAIL(&unlock_bh_queue, next, co_queue_next);
trace_qemu_co_queue_next(next);
unlock_bh = qemu_malloc(sizeof(*unlock_bh));
unlock_bh->bh = qemu_bh_new(qemu_co_queue_next_bh, unlock_bh);
qemu_bh_schedule(unlock_bh->bh);
}
return (next != NULL);
}
bool qemu_co_queue_empty(CoQueue *queue)
{
return (QTAILQ_FIRST(&queue->entries) == NULL);
}
void qemu_co_mutex_init(CoMutex *mutex)
{
memset(mutex, 0, sizeof(*mutex));
qemu_co_queue_init(&mutex->queue);
}
void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex)
{
Coroutine *self = qemu_coroutine_self();
trace_qemu_co_mutex_lock_entry(mutex, self);
while (mutex->locked) {
qemu_co_queue_wait(&mutex->queue);
}
mutex->locked = true;
trace_qemu_co_mutex_lock_return(mutex, self);
}
void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex)
{
Coroutine *self = qemu_coroutine_self();
trace_qemu_co_mutex_unlock_entry(mutex, self);
assert(mutex->locked == true);
assert(qemu_in_coroutine());
mutex->locked = false;
qemu_co_queue_next(&mutex->queue);
trace_qemu_co_mutex_unlock_return(mutex, self);
}

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@ -5,6 +5,7 @@
*
* Authors:
* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
* Kevin Wolf <kwolf@redhat.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
@ -15,6 +16,7 @@
#define QEMU_COROUTINE_H
#include <stdbool.h>
#include "qemu-queue.h"
/**
* Coroutines are a mechanism for stack switching and can be used for
@ -92,4 +94,66 @@ Coroutine *coroutine_fn qemu_coroutine_self(void);
*/
bool qemu_in_coroutine(void);
/**
* CoQueues are a mechanism to queue coroutines in order to continue executing
* them later. They provide the fundamental primitives on which coroutine locks
* are built.
*/
typedef struct CoQueue {
QTAILQ_HEAD(, Coroutine) entries;
} CoQueue;
/**
* Initialise a CoQueue. This must be called before any other operation is used
* on the CoQueue.
*/
void qemu_co_queue_init(CoQueue *queue);
/**
* Adds the current coroutine to the CoQueue and transfers control to the
* caller of the coroutine.
*/
void coroutine_fn qemu_co_queue_wait(CoQueue *queue);
/**
* Restarts the next coroutine in the CoQueue and removes it from the queue.
*
* Returns true if a coroutine was restarted, false if the queue is empty.
*/
bool qemu_co_queue_next(CoQueue *queue);
/**
* Checks if the CoQueue is empty.
*/
bool qemu_co_queue_empty(CoQueue *queue);
/**
* Provides a mutex that can be used to synchronise coroutines
*/
typedef struct CoMutex {
bool locked;
CoQueue queue;
} CoMutex;
/**
* Initialises a CoMutex. This must be called before any other operation is used
* on the CoMutex.
*/
void qemu_co_mutex_init(CoMutex *mutex);
/**
* Locks the mutex. If the lock cannot be taken immediately, control is
* transferred to the caller of the current coroutine.
*/
void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex);
/**
* Unlocks the mutex and schedules the next coroutine that was waiting for this
* lock to be run.
*/
void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex);
#endif /* QEMU_COROUTINE_H */

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@ -433,3 +433,11 @@ disable xen_platform_log(char *s) "xen platform: %s"
disable qemu_coroutine_enter(void *from, void *to, void *opaque) "from %p to %p opaque %p"
disable qemu_coroutine_yield(void *from, void *to) "from %p to %p"
disable qemu_coroutine_terminate(void *co) "self %p"
# qemu-coroutine-lock.c
disable qemu_co_queue_next_bh(void) ""
disable qemu_co_queue_next(void *next) "next %p"
disable qemu_co_mutex_lock_entry(void *mutex, void *self) "mutex %p self %p"
disable qemu_co_mutex_lock_return(void *mutex, void *self) "mutex %p self %p"
disable qemu_co_mutex_unlock_entry(void *mutex, void *self) "mutex %p self %p"
disable qemu_co_mutex_unlock_return(void *mutex, void *self) "mutex %p self %p"