linux-kernel - Re: Linux 5.15-rc1

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Date:   Mon, 13 Sep 2021 15:09:42 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Dave Jones <davej@...emonkey.org.uk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
Subject: Re: Linux 5.15-rc1

On Mon, Sep 13, 2021 at 12:51:30PM -0700, Linus Torvalds wrote:
> On Mon, Sep 13, 2021 at 12:00 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
> >
> > With an older kernel you may experience the stall when accessing the vpd
> > attribute of this device in sysfs.
> 
> Honestly, that old behavior seems to be the *much* better behavior.
> 
> A synchronous stall at boot time is truly annoying, and a pain to deal
> with (and debug).
> 
> That pci_vpd_read() function is clearly NOT designed to deal with
> boot-time callers in the first place, so I think that commit is simply
> wrong.
> 
> And yes, I see that "128ms timeout". If it was _one_ timeout, that
> would be one thing,. But it looks like it's repeated over and over.
> 
> Not acceptable at boot time. Not at all.
> 
> Bjorn. Please revert. Or I can do it.

Sorry about this.

Dave said it wasn't a trivial revert, but I'll be happy to work with
Heiner and Dave to revert and test it.

I agree that we shouldn't read VPD at boot-time unless we actually
need the data then.

Bjorn