linux-kernel - Re: Subject : [ PATCH ] pci-reset-error_state-to-pci_channel_io_normal-at-report_slot

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Message-ID: <CAErSpo7TvCfQLkMD+zL1W6dNEqMpHYbLtAAHqXf==zbxhE2tcQ@mail.gmail.com>
Date:	Mon, 20 May 2013 11:21:17 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	"Zhang, LongX" <longx.zhang@...el.com>,
	"linasvepstas@...il.com" <linasvepstas@...il.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"yanmin_zhang@...ux.intel.com" <yanmin_zhang@...ux.intel.com>,
	"Joseph.Liu@...lex.Com" <Joseph.Liu@...lex.com>
Subject: Re: Subject : [ PATCH ] pci-reset-error_state-to-pci_channel_io_normal-at-report_slot_reset

On Fri, May 17, 2013 at 5:56 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> On Friday, May 17, 2013 05:43:33 PM Bjorn Helgaas wrote:
>> On Fri, Apr 26, 2013 at 12:28 AM, Zhang, LongX <longx.zhang@...el.com> wrote:

>> > +       /* restore cfg space for possible link reset at upstream */
>> > +       dev->state_saved = true;
>>
>> "dev->state_saved == true" means that the dev->saved_config_space
>> contains valid data.  Why do we know that's the case here?  I see that
>> pcie_portdrv_probe() calls pci_save_state() when we first claim the
>> port, and I guess we're assuming the state saved then is still valid.
>> But why do we need to actually set dev->state_saved here?  Shouldn't
>> it be already set to true anyway?
>
> This is a dirty trick to make pci_restore_state(dev) always work here
> (because it checks dev->state_saved and does nothing if it isn't set).
> I suppose.

Yes, I did investigate enough to see that this is a dirty trick.  My
question is how we know it's safe to do this dirty trick.

>> > +       pci_restore_state(dev);
>> > +       pcie_portdrv_restore_config(dev);
>> > +       pci_enable_pcie_error_reporting(dev);
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