From: Emanuele Giuseppe Esposito <eesposit@redhat.com>
To: qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
Emanuele Giuseppe Esposito <eesposit@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>, John Snow <jsnow@redhat.com>
Subject: [PATCH v3 5/5] co-shared-resource: protect with a mutex
Date: Mon, 14 Jun 2021 10:11:30 +0200 [thread overview]
Message-ID: <20210614081130.22134-6-eesposit@redhat.com> (raw)
In-Reply-To: <20210614081130.22134-1-eesposit@redhat.com>
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>
---
include/qemu/co-shared-resource.h | 4 +---
util/qemu-co-shared-resource.c | 24 +++++++++++++++++++-----
2 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/include/qemu/co-shared-resource.h b/include/qemu/co-shared-resource.h
index 4e4503004c..78ca5850f8 100644
--- a/include/qemu/co-shared-resource.h
+++ b/include/qemu/co-shared-resource.h
@@ -26,15 +26,13 @@
#ifndef QEMU_CO_SHARED_RESOURCE_H
#define QEMU_CO_SHARED_RESOURCE_H
-
+/* Accesses to co-shared-resource API are thread-safe */
typedef struct SharedResource SharedResource;
/*
* Create SharedResource structure
*
* @total: total amount of some resource to be shared between clients
- *
- * Note: this API is not thread-safe.
*/
SharedResource *shres_create(uint64_t total);
diff --git a/util/qemu-co-shared-resource.c b/util/qemu-co-shared-resource.c
index 1c83cd9d29..a66cc07e75 100644
--- a/util/qemu-co-shared-resource.c
+++ b/util/qemu-co-shared-resource.c
@@ -28,10 +28,13 @@
#include "qemu/co-shared-resource.h"
struct SharedResource {
- uint64_t total;
- uint64_t available;
+ 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)
@@ -40,6 +43,7 @@ SharedResource *shres_create(uint64_t total)
s->total = s->available = total;
qemu_co_queue_init(&s->queue);
+ qemu_mutex_init(&s->lock);
return s;
}
@@ -47,10 +51,12 @@ SharedResource *shres_create(uint64_t total)
void shres_destroy(SharedResource *s)
{
assert(s->available == s->total);
+ qemu_mutex_destroy(&s->lock);
g_free(s);
}
-bool co_try_get_from_shres(SharedResource *s, uint64_t n)
+/* Called with lock held. */
+static bool co_try_get_from_shres_locked(SharedResource *s, uint64_t n)
{
if (s->available >= n) {
s->available -= n;
@@ -60,16 +66,24 @@ bool co_try_get_from_shres(SharedResource *s, uint64_t n)
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);
- while (!co_try_get_from_shres(s, n)) {
- qemu_co_queue_wait(&s->queue, NULL);
+ 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);
--
2.31.1
next prev parent reply other threads:[~2021-06-14 8:16 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 8:11 [PATCH v3 0/5] block-copy: make helper APIs thread safe Emanuele Giuseppe Esposito
2021-06-14 8:11 ` [PATCH v3 1/5] ratelimit: treat zero speed as unlimited Emanuele Giuseppe Esposito
2021-06-14 8:11 ` [PATCH v3 2/5] block-copy: let ratelimit handle a speed of 0 Emanuele Giuseppe Esposito
2021-06-19 12:04 ` Vladimir Sementsov-Ogievskiy
2021-06-14 8:11 ` [PATCH v3 3/5] blockjob: " Emanuele Giuseppe Esposito
2021-06-14 8:11 ` [PATCH v3 4/5] progressmeter: protect with a mutex Emanuele Giuseppe Esposito
2021-06-19 12:02 ` Vladimir Sementsov-Ogievskiy
2021-06-14 8:11 ` Emanuele Giuseppe Esposito [this message]
2021-06-14 8:17 ` [PATCH v3 0/5] block-copy: make helper APIs thread safe Emanuele Giuseppe Esposito
2021-06-19 12:21 ` Vladimir Sementsov-Ogievskiy
2021-06-19 20:17 ` Vladimir Sementsov-Ogievskiy
2021-06-25 11:27 ` Vladimir Sementsov-Ogievskiy
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