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>,
qemu-block@nongnu.org, qemu-devel@nongnu.org,
Hanna Reitz <hreitz@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>, John Snow <jsnow@redhat.com>
Subject: Re: [RFC PATCH v2 0/8] Removal of AioContext lock, bs->parents and ->children: new rwlock
Date: Thu, 28 Apr 2022 11:34:14 +0100 [thread overview]
Message-ID: <Ymptphd9lpctkTj/@stefanha-x1.localdomain> (raw)
In-Reply-To: <20220426085114.199647-1-eesposit@redhat.com>
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On Tue, Apr 26, 2022 at 04:51:06AM -0400, Emanuele Giuseppe Esposito wrote:
> Next step is the most complex one: figure where to put the rdlocks.
I got a little lost at this step but will hopefully understand more when
reading the patches. Earlier it said there is a counter for readers, so
it seems trivial to make it a recursive lock. I don't understand why you
want to avoid a recursive locking - the complications you described stem
from the fact that you want to avoid recursive locks?
Secondly, can you describe the role of the lock? The text mentions the
old AioContext lock that is being replaced but doesn't define this new
lock in its own right. Is the idea to make ->parents and ->children list
accesses thread-safe and all loops "safe" so they don't break when a BDS
is removed?
Stefan
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next prev parent reply other threads:[~2022-04-28 11:13 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 8:51 [RFC PATCH v2 0/8] Removal of AioContext lock, bs->parents and ->children: new rwlock Emanuele Giuseppe Esposito
2022-04-26 8:51 ` [RFC PATCH v2 1/8] aio_wait_kick: add missing memory barrier Emanuele Giuseppe Esposito
2022-04-28 11:09 ` Stefan Hajnoczi
2022-04-29 8:06 ` Emanuele Giuseppe Esposito
2022-04-30 5:21 ` Stefan Hajnoczi
2022-04-29 8:12 ` Paolo Bonzini
2022-04-26 8:51 ` [RFC PATCH v2 2/8] coroutine-lock: release lock when restarting all coroutines Emanuele Giuseppe Esposito
2022-04-26 14:59 ` Paolo Bonzini
2022-04-28 11:21 ` Stefan Hajnoczi
2022-04-28 22:14 ` Paolo Bonzini
2022-04-29 9:35 ` Emanuele Giuseppe Esposito
2022-04-26 8:51 ` [RFC PATCH v2 3/8] block: introduce a lock to protect graph operations Emanuele Giuseppe Esposito
2022-04-26 15:00 ` Paolo Bonzini
2022-04-28 13:45 ` Stefan Hajnoczi
2022-04-29 8:37 ` Emanuele Giuseppe Esposito
2022-04-30 5:48 ` Stefan Hajnoczi
2022-05-02 7:54 ` Emanuele Giuseppe Esposito
2022-05-03 10:50 ` Stefan Hajnoczi
2022-04-26 8:51 ` [RFC PATCH v2 4/8] async: register/unregister aiocontext in graph lock list Emanuele Giuseppe Esposito
2022-04-28 13:46 ` Stefan Hajnoczi
2022-04-28 22:19 ` Paolo Bonzini
2022-04-29 8:37 ` Emanuele Giuseppe Esposito
2022-04-26 8:51 ` [RFC PATCH v2 5/8] block.c: wrlock in bdrv_replace_child_noperm Emanuele Giuseppe Esposito
2022-04-26 15:07 ` Paolo Bonzini
2022-04-28 13:55 ` Stefan Hajnoczi
2022-04-29 8:41 ` Emanuele Giuseppe Esposito
2022-04-26 8:51 ` [RFC PATCH v2 6/8] block: assert that graph read and writes are performed correctly Emanuele Giuseppe Esposito
2022-04-28 14:43 ` Stefan Hajnoczi
2022-04-26 8:51 ` [RFC PATCH v2 7/8] graph-lock: implement WITH_GRAPH_RDLOCK_GUARD and GRAPH_RDLOCK_GUARD macros Emanuele Giuseppe Esposito
2022-04-28 15:00 ` Stefan Hajnoczi
2022-04-26 8:51 ` [RFC PATCH v2 8/8] mirror: protect drains in coroutine with rdlock Emanuele Giuseppe Esposito
2022-04-27 6:55 ` [RFC PATCH v2 0/8] Removal of AioContext lock, bs->parents and ->children: new rwlock Emanuele Giuseppe Esposito
2022-04-28 10:45 ` Stefan Hajnoczi
2022-04-28 21:56 ` Emanuele Giuseppe Esposito
2022-04-30 5:17 ` Stefan Hajnoczi
2022-05-02 8:02 ` Emanuele Giuseppe Esposito
2022-05-02 13:15 ` Paolo Bonzini
2022-05-03 8:24 ` Kevin Wolf
2022-05-03 11:04 ` Stefan Hajnoczi
2022-04-28 10:34 ` Stefan Hajnoczi [this message]
2022-04-29 8:06 ` Emanuele Giuseppe Esposito
2022-05-04 13:39 ` Stefan Hajnoczi
2022-05-17 10:59 ` Stefan Hajnoczi
2022-05-18 12:28 ` Emanuele Giuseppe Esposito
2022-05-18 12:43 ` Paolo Bonzini
2022-05-18 14:57 ` Stefan Hajnoczi
2022-05-18 16:14 ` Kevin Wolf
2022-05-19 11:27 ` Stefan Hajnoczi
2022-05-19 12:52 ` Kevin Wolf
2022-05-22 15:06 ` Stefan Hajnoczi
2022-05-23 8:48 ` Emanuele Giuseppe Esposito
2022-05-23 13:15 ` Stefan Hajnoczi
2022-05-23 13:54 ` Emanuele Giuseppe Esposito
2022-05-23 13:02 ` Kevin Wolf
2022-05-23 15:13 ` Stefan Hajnoczi
2022-05-23 16:04 ` Kevin Wolf
2022-05-23 16:45 ` Stefan Hajnoczi
2022-05-24 7:55 ` Paolo Bonzini
2022-05-24 8:08 ` Stefan Hajnoczi
2022-05-24 9:17 ` Paolo Bonzini
2022-05-24 10:20 ` Stefan Hajnoczi
2022-05-24 17:25 ` Paolo Bonzini
2022-05-24 10:36 ` Kevin Wolf
2022-05-25 7:41 ` Paolo Bonzini
2022-05-18 14:27 ` Stefan Hajnoczi
2022-05-24 12:10 ` Kevin Wolf
2022-05-25 8:27 ` Emanuele Giuseppe Esposito
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