linux-kernel - Re: [PATCH 2/5] e1000e: fix pci device enable counter balance

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Message-ID: <CAErSpo7g7H8QM4Rgc05ORM1xHPxVf74KX2G61mvMtMF+N=qh5Q@mail.gmail.com>
Date:	Mon, 28 Jan 2013 17:31:44 -0700
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Konstantin Khlebnikov <khlebnikov@...nvz.org>
Cc:	linux-kernel@...r.kernel.org, e1000-devel@...ts.sourceforge.net,
	linux-pci@...r.kernel.org, Bruce Allan <bruce.w.allan@...el.com>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: [PATCH 2/5] e1000e: fix pci device enable counter balance

[+cc Rafael @sisk.pl]

On Mon, Jan 28, 2013 at 4:09 PM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> [+cc Rafael]
>
> On Fri, Jan 18, 2013 at 4:42 AM, Konstantin Khlebnikov
> <khlebnikov@...nvz.org> wrote:
>> __e1000_shutdown() calls pci_disable_device() at the end, thus __e1000_resume()
>> should call pci_enable_device_mem() to keep enable counter in balance.
>>
>> Bug was introduced in commit 23606cf5d1192c2b17912cb2ef6e62f9b11de133
>> ("e1000e / PCI / PM: Add basic runtime PM support (rev. 4)") in v2.6.35
>>
>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...nvz.org>
>> Cc: e1000-devel@...ts.sourceforge.net
>> Cc: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
>> Cc: Bruce Allan <bruce.w.allan@...el.com>
>> ---
>>  drivers/net/ethernet/intel/e1000e/netdev.c |    7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
>> index 2853c11..6bce796 100644
>> --- a/drivers/net/ethernet/intel/e1000e/netdev.c
>> +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
>> @@ -5598,6 +5598,13 @@ static int __e1000_resume(struct pci_dev *pdev)
>>         pci_restore_state(pdev);
>>         pci_save_state(pdev);
>>
>> +       err = pci_enable_device_mem(pdev);
>> +       if (err) {
>> +               dev_err(&pdev->dev,
>> +                       "Cannot re-enable PCI device after suspend.\n");
>> +               return err;
>> +       }
>
> Reviewed-by: Bjorn Helgaas <bhelgaas@...gle.com>
>
> Seems right to me, and the other users I looked at (igb, azx,
> virtio_pci) call pci_disable_device() in .suspend() and call
> pci_enable_device() in .resume() as you propose to do here.
>
> I assume the e1000 folks will handle this patch (and the previous one).
>
>> +
>>         e1000e_set_interrupt_capability(adapter);
>>         if (netif_running(netdev)) {
>>                 err = e1000_request_irq(adapter);
>>

I'm still missing something.  In your original report
(https://lkml.org/lkml/2013/1/1/25), you noticed that "enable_cnt ==
0" immediately after boot, after e1000e had claimed the device:

> Right after boot it looks like this:
>
> root@...g:/sys/bus/pci/devices# lspci
> ...
> 00:19.0 Ethernet controller: Intel Corporation 82579LM Gigabit Network Connection (rev 04)
> ...
> root@...g:/sys/bus/pci/devices# cat 0000\:00\:19.0/enable
> 0
> here must be '1', not '0'

But these patches only change the e1000e suspend/resume path.  How
could they change the enable_cnt before you've even done a suspend?

Bjorn
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