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From: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
To: Avi Kivity <avi@redhat.com>
Cc: Takuya Yoshikawa <takuya.yoshikawa@gmail.com>,
	mtosatti@redhat.com, kvm@vger.kernel.org,
	kvm-ia64@vger.kernel.org
Subject: Re: [PATCH 2/3] KVM: Centralize slots_lock aquisition during KVM_CREATE_IRQCHIP
Date: Thu, 16 Dec 2010 18:47:34 +0900	[thread overview]
Message-ID: <4D09E036.2090705@oss.ntt.co.jp> (raw)
In-Reply-To: <4D09DD3F.5070408@redhat.com>

(2010/12/16 18:34), Avi Kivity wrote:
>>> Maybe we ought to move slots_lock acquisition to kvm_io_bus_register() and friends.
>>>
>>
>>
>> So it will move the lock acquisition to the opposite ( callee ) side than mine.
>> At first, I tried to do that, but there are so many ...
>>
>> Anyway, your suggestion seems to be the best way if possible.
>>
>>
>> One question: how about kvm_io_bus_[read|write] ?
>>
>> These are called from the emulator but I could not find where slots_lock
>> are held though I can see the comments
>>
>> "kvm_io_bus_[read|write] - called under kvm->slots_lock"
>>
>
> They're under srcu now, the comments are outdated.
>
> We used to have slots_lock be a rwsem, taken for read or write as necessary. Now we use srcu for read, and the slots_lock mutex + synchronize_srcu for write.
>

Ah, would you mind updating the comments?
  - or just removing outdated ones?


I will reread these locking based on your answer!


Thanks,
   Takuya

  reply	other threads:[~2010-12-16  9:44 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-15 16:39 [PATCH-v2 0/3] KVM: Take missing slots_lock for kvm_io_bus_unregister_dev() Takuya Yoshikawa
2010-12-15 16:41 ` [PATCH 1/3] " Takuya Yoshikawa
2010-12-16  9:12   ` Avi Kivity
2010-12-15 16:43 ` [PATCH 2/3] KVM: Centralize slots_lock aquisition during KVM_CREATE_IRQCHIP Takuya Yoshikawa
2010-12-16  9:11   ` Avi Kivity
2010-12-16  9:29     ` Takuya Yoshikawa
2010-12-16  9:34       ` Avi Kivity
2010-12-16  9:47         ` Takuya Yoshikawa [this message]
2010-12-16  9:55           ` Avi Kivity
2010-12-16 12:51             ` Takuya Yoshikawa
2010-12-15 16:45 ` [PATCH 3/3] KVM: Centralize irq_lock " Takuya Yoshikawa

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