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From: Jiang Liu <email@example.com>
To: "Rafael J. Wysocki" <firstname.lastname@example.org>
Cc: "Luck, Tony" <email@example.com>,
Alex Williamson <firstname.lastname@example.org>,
Bjorn Helgaas <email@example.com>,
"firstname.lastname@example.org" <email@example.com>, "Zheng, Lv" <firstname.lastname@example.org>,
Subject: Re: [PATCH] x86/PCI: Fully disable devices before releasing IRQ resource
Date: Fri, 13 Mar 2015 09:49:06 +0800 [thread overview]
Message-ID: <email@example.com> (raw)
On 2015/3/13 0:08, Rafael J. Wysocki wrote:
> On Thursday, March 12, 2015 09:41:21 AM Jiang Liu wrote:
>> On 2015/3/12 9:17, Rafael J. Wysocki wrote:
>>> On Wednesday, March 11, 2015 10:04:42 PM Luck, Tony wrote:
>>>>>> Unfortunately there's a long standing comment in pci_device_remove():
>>>>>> * We would love to complain here if pci_dev->is_enabled is set, that
>>>>>> * the driver should have called pci_disable_device(), but the
>>>>>> * unfortunate fact is there are too many odd BIOS and bridge setups
>>>>>> * that don't like drivers doing that all of the time.
>>>>>> * Oh well, we can dream of sane hardware when we sleep, no matter how
>>>>>> * horrible the crap we have to deal with is when we are awake...
>>>>>> So, unless we can somehow ignore that comment, I suspect forcing the
>>>>>> device to be disabled on driver remove, whether done from pci-core or
>>>>>> from x86/pci, is going to cause all sorts of breakage. Are the
>>>>>> expectations set by b4b55cda5874 really valid? It seems like something
>>>>>> needs to be done to allow the IRQ to be automatically re-established on
>>>>>> x86 regardless of the driver doing the right thing when releasing the
>>>>>> device. We're still looking at a regression for v4.0 as a result of
>>>>> In which case we probably should revert commit b4b55cda5874 for the time being.
>>>>> At least I'd be very nervous about any ad-hoc fixes at this stage of the cycle.
>>>> The comment goes back to the dawn of "git" time ... not sure how much further
>>>> Is this actually still an issue on modern systems? Maybe we need a black list
>>>> or white list to separate the good from bad systems?
>>> The answer to that is "We don't know" and in my not so humble opinion it is too
>>> risky to try to find out at the end of the cycle.
>> Hi Rafael and Alex,
>> How about a patch which:
>> 1) gives a warning if PCI device is still enabled when unloading driver
> That may become sort of noisy. I really would prefer to introduce things like
> that by the beginning of the cycle, not by the end of it.
Will try this on next merging window.
>> 2) release PCI interrupt only if PCI device is disabled.
>> By this way, we could support IOAPIC hot-removal on latest platforms and
>> avoid regressions on old platforms.
> Well, please submit a patch for discussion.
> I would like to know Bjorn's opinion about that too at least.
Still testing the patch, will send it out soon.
next prev parent reply other threads:[~2015-03-13 1:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-05 21:06 Alex Williamson
2015-03-06 1:49 ` Jiang Liu
2015-03-06 3:51 ` Alex Williamson
2015-03-11 16:47 ` Alex Williamson
2015-03-11 22:04 ` Rafael J. Wysocki
2015-03-11 22:04 ` Luck, Tony
2015-03-12 1:17 ` Rafael J. Wysocki
2015-03-12 1:41 ` Jiang Liu
2015-03-12 16:08 ` Rafael J. Wysocki
2015-03-13 1:49 ` Jiang Liu [this message]
2015-03-13 2:06 ` [Bugfix] x86/PCI: Release PCI IRQ resource only if PCI device is disabled when unbinding Jiang Liu
2015-03-13 21:45 ` Rafael J. Wysocki
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