From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Xu <peterx@redhat.com>
Cc: "Chuang Xu" <xuchuangxclwt@bytedance.com>,
qemu-devel <qemu-devel@nongnu.org>,
"David Gilbert" <dgilbert@redhat.com>,
"Quintela, Juan" <quintela@redhat.com>,
"David Hildenbrand" <david@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@linaro.org>,
zhouyibo@bytedance.com
Subject: Re: [RFC v4 2/3] memory: add depth assert in address_space_to_flatview
Date: Wed, 28 Dec 2022 09:27:50 +0100 [thread overview]
Message-ID: <CABgObfa=i=9CZRFyX_EXBOSW===iDhcZoDO8Ju64F-tHUAXdRA@mail.gmail.com> (raw)
In-Reply-To: <Y6XPRD4fSucgWZfT@x1n>
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Il ven 23 dic 2022, 16:54 Peter Xu <peterx@redhat.com> ha scritto:
> > This is not valid because the transaction could happen in *another*
> thread.
> > In that case memory_region_transaction_depth() will be > 0, but RCU is
> > needed.
>
> Do you mean the code is wrong, or the comment? Note that the code has
> checked rcu_read_locked() where introduced in patch 1, but maybe something
> else was missed?
>
The assertion is wrong. It will succeed even if RCU is unlocked in this
thread but a transaction is in progress in another thread.
Perhaps you can check (memory_region_transaction_depth() > 0 &&
!qemu_mutex_iothread_locked()) || rcu_read_locked() instead?
Paolo
Thanks,
>
> --
> Peter Xu
>
>
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next prev parent reply other threads:[~2022-12-28 8:28 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-23 14:23 [RFC v4 0/3] migration: reduce time of loading non-iterable vmstate Chuang Xu
2022-12-23 14:23 ` [RFC v4 1/3] rcu: introduce rcu_read_locked() Chuang Xu
2023-01-04 14:20 ` Alex Bennée
2023-01-05 8:17 ` Chuang Xu
2022-12-23 14:23 ` [RFC v4 2/3] memory: add depth assert in address_space_to_flatview Chuang Xu
2022-12-23 15:37 ` Peter Xu
2022-12-23 15:47 ` Paolo Bonzini
2022-12-23 15:54 ` Peter Xu
2022-12-28 8:27 ` Paolo Bonzini [this message]
2023-01-03 17:43 ` Peter Xu
2023-01-10 8:09 ` Chuang Xu
2023-01-10 14:45 ` Peter Xu
2023-01-12 7:59 ` Chuang Xu
2023-01-12 15:13 ` Peter Xu
2023-01-13 19:29 ` Chuang Xu
2022-12-28 10:50 ` Philippe Mathieu-Daudé
2023-01-04 7:39 ` [External] " Chuang Xu
2022-12-23 14:23 ` [RFC v4 3/3] migration: reduce time of loading non-iterable vmstate Chuang Xu
2022-12-23 16:06 ` David Hildenbrand
2023-01-04 7:31 ` Chuang Xu
2022-12-23 15:50 ` [RFC v4 0/3] " Peter Xu
2022-12-23 19:11 ` Chuang Xu
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