diff options
| author |   Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com> | 2023-10-10 11:40:56 +0000 |
|---|---|---|
| committer | Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com> | 2023-10-10 11:40:56 +0000 |
| commit | e02cda008591317b1625707ff8e115a4841aa889 (patch) | |
| tree | aee302e3cf8b59ec2d32ec481be3d1afddfc8968 /util/qemu-co-shared-resource.c | |
| parent | cc668e6b7e0ffd8c9d130513d12053cf5eda1d3b (diff) | |
Introduce Virtio-loopback epsilon release:
Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.
Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9
Diffstat (limited to 'util/qemu-co-shared-resource.c')
| -rw-r--r-- | util/qemu-co-shared-resource.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/util/qemu-co-shared-resource.c b/util/qemu-co-shared-resource.c new file mode 100644 index 000000000..a66cc07e7 --- /dev/null +++ b/util/qemu-co-shared-resource.c @@ -0,0 +1,90 @@ +/* + * 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); +} |