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From: Ethan Zhao <xerces.zhao@gmail.com>
To: Lukas Wunner <lukas@wunner.de>
Cc: Ethan Zhao <haifeng.zhao@intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>, Oliver <oohall@gmail.com>,
	ruscur@russell.cc,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Stuart Hayes <stuart.w.hayes@gmail.com>,
	Alexandru Gagniuc <mr.nuke.me@gmail.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	linux-pci <linux-pci@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"Raj, Ashok" <ashok.raj@linux.intel.com>,
	Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@intel.com>
Subject: Re: [PATCH v7 3/5] PCI: pciehp: check and wait port status out of DPC before handling DLLSC and PDC
Date: Wed, 7 Oct 2020 15:48:17 +0800	[thread overview]
Message-ID: <CAKF3qh1coHqCHqpa_f8Mh4Ere+_xE2qACoNSyo2wYiOboYiNjQ@mail.gmail.com> (raw)
In-Reply-To: <20201004191329.GA27962@wunner.de>

Lukas,

On Mon, Oct 5, 2020 at 3:13 AM Lukas Wunner <lukas@wunner.de> wrote:
>
> On Sat, Oct 03, 2020 at 03:55:12AM -0400, Ethan Zhao wrote:
> > When root port has DPC capability and it is enabled, then triggered by
> > errors, DPC DLLSC and PDC etc interrupts will be sent to DPC driver, pciehp
> > drivers almost at the same time.
>
> Do the DLLSC and PDC events occur as a result of handling the error
> or do they occur independently?
They could happen independently if links were recovered then the card
was removed.
They could happen as a result of handling the errors the same time.

So don't assume DLLSC and PDC all occur at the same time.

>
> If the latter, I don't see how we can tell whether the card in the
> slot is still the same.
If PDC happens, the card in the slot might not be the same.  so
hot-removal /hot -plugin handling follows the PDC event.
>
> If the former, holding the hotplug slot's reset_lock and doing something
> along the lines of pciehp_reset_slot() (or calling it directly) might
> solve the race.

DPC reset is done by hardware, only AER calls pciehp_reset_slot() as recovery
handling initiated by software.

Thanks,
Ethan
>
> Thanks,
>
> Lukas

  reply	other threads:[~2020-10-07  7:48 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-03  7:55 [PATCH v7 0/5] Fix DPC hotplug race and enhance error handling Ethan Zhao
2020-10-03  7:55 ` [PATCH v7 1/5] PCI/ERR: get device before call device driver to avoid NULL pointer dereference Ethan Zhao
2020-10-03  7:55 ` [PATCH v7 2/5] PCI/DPC: define a function to check and wait till port finish DPC handling Ethan Zhao
2020-10-03  7:55 ` [PATCH v7 3/5] PCI: pciehp: check and wait port status out of DPC before handling DLLSC and PDC Ethan Zhao
2020-10-04 19:13   ` Lukas Wunner
2020-10-07  7:48     ` Ethan Zhao [this message]
2020-10-03  7:55 ` [PATCH v7 4/5] PCI: only return true when dev io state is really changed Ethan Zhao
2020-10-03 16:44   ` Bjorn Helgaas
2020-10-07  7:50     ` Ethan Zhao
2020-10-03  7:55 ` [PATCH v7 5/5] PCI/ERR: don't mix io state not changed and no driver together Ethan Zhao
2020-10-04  4:57 ` [PATCH v7 0/5] Fix DPC hotplug race and enhance error handling Raj, Ashok
2020-10-07  7:33   ` Ethan Zhao

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