From: Stefan Hajnoczi <stefanha@redhat.com>
To: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Cc: "Kevin Wolf" <kwolf@redhat.com>, "Fam Zheng" <fam@euphon.net>,
"Vladimir Sementsov-Ogievskiy" <vsementsov@virtuozzo.com>,
"Daniel P. Berrangé" <berrange@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
qemu-block@nongnu.org, "Juan Quintela" <quintela@redhat.com>,
"John Snow" <jsnow@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
qemu-devel@nongnu.org, "Hanna Reitz" <hreitz@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Eric Blake" <eblake@redhat.com>
Subject: Re: [RFC PATCH 3/4] include/sysemu/block-backend: split header into I/O and graph API
Date: Mon, 13 Sep 2021 14:41:09 +0100 [thread overview]
Message-ID: <YT9U9cD+KrbDP30B@stefanha-x1.localdomain> (raw)
In-Reply-To: <20210908131021.774533-4-eesposit@redhat.com>
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On Wed, Sep 08, 2021 at 09:10:20AM -0400, Emanuele Giuseppe Esposito wrote:
> +/*
> + * Graph API. These functions run under the BQL lock.
> + *
> + * If a function modifies the graph, it uses drain and/or
> + * aio_context_acquire/release to be sure it has unique access.
> + *
> + * All functions in this header must use this assertion:
> + * g_assert(qemu_in_main_thread());
> + * to be sure they belong here.
> + */
It's important to note that not all of these functions are necessarily
limited to running under the BQL, but they would require additional
auditing and may small thread-safety changes to move them into the I/O
API. Often it's not worth doing that work since the APIs are only used
with the BQL held at the moment, so they have been placed in the graph
API (for now).
Stefan
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next prev parent reply other threads:[~2021-09-13 13:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-08 13:10 [RFC PATCH 0/4] block layer: split block APIs in graph and I/O Emanuele Giuseppe Esposito
2021-09-08 13:10 ` [RFC PATCH 1/4] main-loop.h: introduce qemu_in_main_thread() Emanuele Giuseppe Esposito
2021-09-13 13:15 ` Stefan Hajnoczi
2021-09-08 13:10 ` [RFC PATCH 2/4] migration: block-dirty-bitmap: add missing qemu_mutex_lock_iothread Emanuele Giuseppe Esposito
2021-09-13 13:19 ` Stefan Hajnoczi
2021-09-08 13:10 ` [RFC PATCH 3/4] include/sysemu/block-backend: split header into I/O and graph API Emanuele Giuseppe Esposito
2021-09-13 13:27 ` Stefan Hajnoczi
2021-09-15 12:14 ` Paolo Bonzini
2021-09-15 14:38 ` Stefan Hajnoczi
2021-09-13 13:41 ` Stefan Hajnoczi [this message]
2021-09-08 13:10 ` [RFC PATCH 4/4] block/block-backend.c: assertions for block-backend Emanuele Giuseppe Esposito
2021-09-13 13:38 ` Stefan Hajnoczi
2021-09-13 13:10 ` [RFC PATCH 0/4] block layer: split block APIs in graph and I/O Stefan Hajnoczi
2021-09-15 12:11 ` Paolo Bonzini
2021-09-15 14:43 ` Stefan Hajnoczi
2021-09-16 14:03 ` Emanuele Giuseppe Esposito
2021-09-16 19:49 ` Paolo Bonzini
2021-09-13 13:39 ` Stefan Hajnoczi
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