From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: Emanuele Giuseppe Esposito <eesposit@redhat.com>, qemu-block@nongnu.org
Cc: John Snow <jsnow@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Kevin Wolf <kwolf@redhat.com>, Max Reitz <mreitz@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
qemu-devel@nongnu.org
Subject: Re: [PATCH 5/6] co-shared-resource: protect with a mutex
Date: Mon, 10 May 2021 14:40:21 +0300 [thread overview]
Message-ID: <57fd4d5f-4645-905f-998c-a120c042fdc7@virtuozzo.com> (raw)
In-Reply-To: <20210510085941.22769-6-eesposit@redhat.com>
10.05.2021 11:59, Emanuele Giuseppe Esposito wrote:
> 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.
But it doesn't. It's called only from co_get_from_shres(). So, better make it a static function first.
>
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> ---
> util/qemu-co-shared-resource.c | 26 ++++++++++++++++++++++----
> 1 file changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/util/qemu-co-shared-resource.c b/util/qemu-co-shared-resource.c
> index 1c83cd9d29..c455d02a1e 100644
> --- a/util/qemu-co-shared-resource.c
> +++ b/util/qemu-co-shared-resource.c
> @@ -32,6 +32,7 @@ struct SharedResource {
> uint64_t available;
>
> CoQueue queue;
> + QemuMutex lock;
> };
>
> SharedResource *shres_create(uint64_t total)
> @@ -40,17 +41,23 @@ SharedResource *shres_create(uint64_t total)
>
> 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);
> + WITH_QEMU_LOCK_GUARD(&s->lock) {
> + assert(s->available == s->total);
> + }
shres_destroy can't be thread-safe anyway, as it does qemu_mutex_destroy() and g_free. So, let's don't try to make part of shres_destroy() "thread safe".
> +
> + qemu_mutex_destroy(&s->lock);
> g_free(s);
> }
>
> -bool co_try_get_from_shres(SharedResource *s, uint64_t n)
> +/* Called with lock held */
it should be called _locked() than.
> +static bool co_try_get_from_shres_unlocked(SharedResource *s, uint64_t n)> {
> if (s->available >= n) {
> s->available -= n;
> @@ -60,16 +67,27 @@ bool co_try_get_from_shres(SharedResource *s, uint64_t n)
> return false;
> }
>
> +bool co_try_get_from_shres(SharedResource *s, uint64_t n)
> +{
> + bool res;
> + QEMU_LOCK_GUARD(&s->lock);
> + res = co_try_get_from_shres_unlocked(s, n);
> +
> + return res;
> +}
> +
> void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n)
> {
> + QEMU_LOCK_GUARD(&s->lock);
> assert(n <= s->total);
> - while (!co_try_get_from_shres(s, n)) {
> - qemu_co_queue_wait(&s->queue, NULL);
> + while (!co_try_get_from_shres_unlocked(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);
>
--
Best regards,
Vladimir
next prev parent reply other threads:[~2021-05-10 11:42 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-10 8:59 [PATCH 0/6] block-copy: make helper APIs thread safe Emanuele Giuseppe Esposito
2021-05-10 8:59 ` [PATCH 1/6] ratelimit: treat zero speed as unlimited Emanuele Giuseppe Esposito
2021-05-10 11:00 ` Vladimir Sementsov-Ogievskiy
2021-05-10 8:59 ` [PATCH 2/6] block-copy: let ratelimit handle a speed of 0 Emanuele Giuseppe Esposito
2021-05-10 11:06 ` Vladimir Sementsov-Ogievskiy
2021-05-10 8:59 ` [PATCH 3/6] blockjob: " Emanuele Giuseppe Esposito
2021-05-10 11:17 ` Vladimir Sementsov-Ogievskiy
2021-05-10 8:59 ` [PATCH 4/6] progressmeter: protect with a mutex Emanuele Giuseppe Esposito
2021-05-10 11:28 ` Vladimir Sementsov-Ogievskiy
2021-05-10 16:52 ` Emanuele Giuseppe Esposito
2021-05-10 17:17 ` Vladimir Sementsov-Ogievskiy
2021-05-10 17:57 ` Emanuele Giuseppe Esposito
2021-05-11 12:28 ` Paolo Bonzini
2021-05-12 7:09 ` Vladimir Sementsov-Ogievskiy
2021-05-12 15:53 ` Stefan Hajnoczi
2021-05-10 8:59 ` [PATCH 5/6] co-shared-resource: " Emanuele Giuseppe Esposito
2021-05-10 11:40 ` Vladimir Sementsov-Ogievskiy [this message]
2021-05-11 8:34 ` Paolo Bonzini
2021-05-12 15:44 ` Stefan Hajnoczi
2021-05-12 18:30 ` Paolo Bonzini
2021-05-14 14:10 ` Emanuele Giuseppe Esposito
2021-05-14 14:26 ` Vladimir Sementsov-Ogievskiy via
2021-05-14 14:32 ` Emanuele Giuseppe Esposito
2021-05-14 15:30 ` Vladimir Sementsov-Ogievskiy via
2021-05-14 17:28 ` Emanuele Giuseppe Esposito
2021-05-14 21:15 ` Vladimir Sementsov-Ogievskiy via
2021-05-14 21:53 ` Emanuele Giuseppe Esposito
2021-05-15 7:11 ` Vladimir Sementsov-Ogievskiy via
2021-05-14 17:55 ` Paolo Bonzini
2021-05-10 8:59 ` [PATCH 6/6] aiopool: " Emanuele Giuseppe Esposito
2021-05-10 11:56 ` Vladimir Sementsov-Ogievskiy
2021-05-11 8:34 ` Paolo Bonzini
2021-05-12 15:19 ` Stefan Hajnoczi
2021-05-10 10:55 ` [PATCH 0/6] block-copy: make helper APIs thread safe Vladimir Sementsov-Ogievskiy
2021-05-12 14:24 ` Stefan Hajnoczi
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