From: John Snow <jsnow@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Lieven <pl@kamp.de>, qemu block <qemu-block@nongnu.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [Qemu-block] Limiting coroutine stack usage
Date: Thu, 22 Feb 2018 12:06:44 -0500 [thread overview]
Message-ID: <c374c10a-a46c-1870-8f2c-47a2841b8a44@redhat.com> (raw)
In-Reply-To: <20180222105755.GB4147@localhost.localdomain>
On 02/22/2018 05:57 AM, Kevin Wolf wrote:
> Am 20.02.2018 um 22:54 hat Paolo Bonzini geschrieben:
>> On 20/02/2018 18:04, Peter Lieven wrote:
>>> Hi,
>>>
>>> I remember we discussed a long time ago to limit the stack usage of all
>>> functions that are executed in a coroutine
>>> context to a very low value to be able to safely limit the coroutine
>>> stack size as well.
>>
>> IIRC the only issue was that hw/ide/atapi.c has mutual recursion between
>> ide_atapi_cmd_reply_end -> ide_transfer_start -> ahci_start_transfer ->
>> ide_atapi_cmd_reply_end.
>>
>> But perhaps it's not an issue, somebody needs to audit the code.
>
> I think John intended to get rid of the recursion sometime, but I doubt
> he has had the time so far.
>
It hasn't been a priority for me.
Paolo tried to fix ATAPI by adding a BH callback, but that added the
possibility of a migration halfway through a data transfer IIRC.
If anyone wants to tackle it, I'll dig up Paolo's patches.
--js
next prev parent reply other threads:[~2018-02-22 17:07 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-20 17:04 [Qemu-devel] Limiting coroutine stack usage Peter Lieven
2018-02-20 21:54 ` [Qemu-devel] [Qemu-block] " Paolo Bonzini
2018-02-22 10:57 ` Kevin Wolf
2018-02-22 11:01 ` Peter Lieven
2018-02-22 11:32 ` Kevin Wolf
2018-02-22 11:40 ` Daniel P. Berrangé
2018-02-22 11:51 ` Peter Lieven
2018-02-22 12:00 ` Daniel P. Berrangé
2018-02-22 12:02 ` Peter Lieven
2018-02-22 12:03 ` Daniel P. Berrangé
2018-02-22 12:06 ` Peter Lieven
2018-02-22 12:16 ` Daniel P. Berrangé
2018-02-22 12:19 ` Kevin Wolf
2018-02-22 11:42 ` Peter Lieven
2018-02-22 17:06 ` John Snow [this message]
2018-02-23 11:17 ` Paolo Bonzini
2018-03-06 11:51 ` Stefan Hajnoczi
2018-03-07 20:36 ` Peter Lieven
2018-03-08 17:27 ` Stefan Hajnoczi
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