mirror of
https://github.com/qemu/qemu.git
synced 2025-10-31 04:06:46 +00:00
55fa54a789
co-shared-resource is currently not thread-safe, as also reported in co-shared-resource.h. Add a QemuMutex because co_try_get_from_shres can also be invoked from non-coroutine context. Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Message-Id: <20210614081130.22134-6-eesposit@redhat.com> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
91 lines
2.6 KiB
C
91 lines
2.6 KiB
C
/*
|
|
* Helper functionality for distributing a fixed total amount of
|
|
* an abstract resource among multiple coroutines.
|
|
*
|
|
* Copyright (c) 2019 Virtuozzo International GmbH
|
|
*
|
|
* 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/osdep.h"
|
|
#include "qemu/coroutine.h"
|
|
#include "qemu/co-shared-resource.h"
|
|
|
|
struct SharedResource {
|
|
uint64_t total; /* Set in shres_create() and not changed anymore */
|
|
|
|
/* State fields protected by lock */
|
|
uint64_t available;
|
|
CoQueue queue;
|
|
|
|
QemuMutex lock;
|
|
};
|
|
|
|
SharedResource *shres_create(uint64_t total)
|
|
{
|
|
SharedResource *s = g_new0(SharedResource, 1);
|
|
|
|
s->total = s->available = total;
|
|
qemu_co_queue_init(&s->queue);
|
|
qemu_mutex_init(&s->lock);
|
|
|
|
return s;
|
|
}
|
|
|
|
void shres_destroy(SharedResource *s)
|
|
{
|
|
assert(s->available == s->total);
|
|
qemu_mutex_destroy(&s->lock);
|
|
g_free(s);
|
|
}
|
|
|
|
/* Called with lock held. */
|
|
static bool co_try_get_from_shres_locked(SharedResource *s, uint64_t n)
|
|
{
|
|
if (s->available >= n) {
|
|
s->available -= n;
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
bool co_try_get_from_shres(SharedResource *s, uint64_t n)
|
|
{
|
|
QEMU_LOCK_GUARD(&s->lock);
|
|
return co_try_get_from_shres_locked(s, n);
|
|
}
|
|
|
|
void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n)
|
|
{
|
|
assert(n <= s->total);
|
|
QEMU_LOCK_GUARD(&s->lock);
|
|
while (!co_try_get_from_shres_locked(s, n)) {
|
|
qemu_co_queue_wait(&s->queue, &s->lock);
|
|
}
|
|
}
|
|
|
|
void coroutine_fn co_put_to_shres(SharedResource *s, uint64_t n)
|
|
{
|
|
QEMU_LOCK_GUARD(&s->lock);
|
|
assert(s->total - s->available >= n);
|
|
s->available += n;
|
|
qemu_co_queue_restart_all(&s->queue);
|
|
}
|