linux-kernel - Re: [PATCH] PCI: Do not enable INTx in pci_reenable

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Date:	Mon, 17 Mar 2014 10:23:48 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Chris Cheng <chris.cheng@...ustcorp.com>,
	Jamie Chen <jamie.chen@...el.com>,
	Andreas Noever <andreas.noever@...il.com>
Subject: Re: [PATCH] PCI: Do not enable INTx in pci_reenable_device()

On Fri, Mar 14, 2014 at 6:30 PM, Yinghai Lu <yinghai@...nel.org> wrote:
> On Tue, Mar 11, 2014 at 10:48 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
>> Andreas reported that after 1f42db786b14 ("PCI: Enable INTx if BIOS left
>> them disabled"), pciehp surprise removal stopped working.
>>
>> This happens because pci_reenable_device() on the hotplug bridge (used in
>> the pciehp_configure_device() path) clears the Interrupt Disable bit, which
>> apparently breaks the bridge's MSI hotplug event reporting.
>>
>> Previously we cleared the Interrupt Disable bit in do_pci_enable_device(),
>> which is used by both pci_enable_device() and pci_reenable_device().  But
>> we use pci_reenable_device() after the driver may have enabled MSI or
>> MSI-X, and we *set* Interrupt Disable as part of enabling MSI/MSI-X.
>>
>> This patch clears Interrupt Disable only when MSI/MSI-X has not been
>> enabled.
>>
>> Fixes: 1f42db786b14 PCI: Enable INTx if BIOS left them disabled
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=71691
>> Reported-and-tested-by: Andreas Noever <andreas.noever@...il.com>
>> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
>> CC: stable@...r.kernel.org
>> CC: Sarah Sharp <sarah.a.sharp@...ux.intel.com>
>> ---
>>  drivers/pci/pci.c |    3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index 8dc3e701ec57..79fc89c6c3f3 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -1192,6 +1192,9 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars)
>>                 return err;
>>         pci_fixup_device(pci_fixup_enable, dev);
>>
>> +       if (dev->msi_enabled || dev->msix_enabled)
>> +               return 0;
>> +
>>         pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
>>         if (pin) {
>>                 pci_read_config_word(dev, PCI_COMMAND, &cmd);
>
> looks ugly.
>
> We really should move out those irq handling out of pci_enable_device.

OK, I'll watch for your patch.

Bjorn
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