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Re: [Qemu-block] [Qemu-devel] [PATCH] throttle: Assert that bkt->max is
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From: |
Alberto Garcia |
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Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH] throttle: Assert that bkt->max is valid in throttle_compute_wait() |
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Date: |
Thu, 14 Sep 2017 11:00:19 +0200 |
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User-agent: |
Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Wed 13 Sep 2017 06:31:58 PM CEST, Philippe Mathieu-Daudé wrote:
>> If bkt->max == 0 and bkt->burst_length > 1 then we could have a
>> division by 0 in throttle_do_compute_wait(). That configuration is
>> however not permitted and is already detected by throttle_is_valid(),
>> but let's assert it in throttle_compute_wait() to make it explicit.
>
> This is correct but I'm not sure this is enough, as
> throttle_compute_wait() is exported/public, however it seems testing
> is the only reason to export it.
You're right but in general I don't think the throttling code is
guaranteed to behave correctly if the configuration hasn't been checked
with throttle_is_valid() first.
> Also I spent 10min looking at it thinking about how bkt->max is used,
> before to realize there should be a simpler way to write this (KISS).
I'm sure there is :) if you have suggestions I'll be glad to hear them.
Berto