Linux-PCI Archive on lore.kernel.org
 help / color / Atom feed
From: Sinan Kaya <okaya@kernel.org>
To: "Kuppuswamy,
	Sathyanarayanan"  <sathyanarayanan.kuppuswamy@linux.intel.com>,
	Bjorn Helgaas <helgaas@kernel.org>
Cc: bhelgaas@google.com, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, ashok.raj@intel.com,
	Jay Vosburgh <jay.vosburgh@canonical.com>
Subject: Re: [PATCH v3 1/1] PCI/ERR: Fix reset logic in pcie_do_recovery() call
Date: Mon, 28 Sep 2020 07:17:24 -0400
Message-ID: <a2bbdfed-fb17-51dc-8ae4-55d924c13211@kernel.org> (raw)
In-Reply-To: <3bc0fd23-8ddd-32c5-1dd9-4d5209ea68c3@linux.intel.com>

On 9/27/2020 10:43 PM, Kuppuswamy, Sathyanarayanan wrote:
> FATAL + no-hotplug - In this case, link will still be reseted. But
> currently driver state is not properly restored. So I attempted
> to restore it using pci_reset_bus().
> 
>          status = reset_link(dev);
> -        if (status != PCI_ERS_RESULT_RECOVERED) {
> +        if (status == PCI_ERS_RESULT_RECOVERED) {
> +            status = PCI_ERS_RESULT_NEED_RESET;
> 
> ...
> 
>      if (status == PCI_ERS_RESULT_NEED_RESET) {
>          /*
> -         * TODO: Should call platform-specific
> -         * functions to reset slot before calling
> -         * drivers' slot_reset callbacks?
> +         * TODO: Optimize the call to pci_reset_bus()
> +         *
> +         * There are two components to pci_reset_bus().
> +         *
> +         * 1. Do platform specific slot/bus reset.
> +         * 2. Save/Restore all devices in the bus.
> +         *
> +         * For hotplug capable devices and fatal errors,
> +         * device is already in reset state due to link
> +         * reset. So repeating platform specific slot/bus
> +         * reset via pci_reset_bus() call is redundant. So
> +         * can optimize this logic and conditionally call
> +         * pci_reset_bus().
>           */
> +        pci_reset_bus(dev);

I think we have to go to remove/rescan for this case as you also
mentioned above. There is no state to save. All BAR assignments
are gone. Entire device programming is also lost.

I don't think pci_reset_bus() can recover from this situation safely.
It will make things worse by saving/restoring the hardware default
state.

This should remove/rescan logic should be inside DPC's slot_reset()
function BTW. Not here.

  parent reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <3cad1a07-509b-ef51-f635-71def2ff8293@linux.intel.com>
2020-09-22 23:33 ` Bjorn Helgaas
2020-09-22 23:44   ` Kuppuswamy, Sathyanarayanan
2020-09-24  1:15     ` Sinan Kaya
2020-09-24  2:04       ` Kuppuswamy, Sathyanarayanan
2020-09-24  2:16         ` Sinan Kaya
2020-09-24  2:51           ` Kuppuswamy, Sathyanarayanan
2020-09-24  3:13             ` Sinan Kaya
2020-09-24  4:06               ` Kuppuswamy, Sathyanarayanan
2020-09-24 20:52                 ` Sinan Kaya
2020-09-25  5:11                   ` Kuppuswamy, Sathyanarayanan
2020-09-25 16:55                     ` Sinan Kaya
2020-09-25 17:11                       ` Kuppuswamy, Sathyanarayanan
2020-09-25 17:47                         ` Sinan Kaya
2020-09-25 18:16                           ` Kuppuswamy, Sathyanarayanan
2020-09-25 18:30                             ` Sinan Kaya
2020-09-28  2:43                               ` Kuppuswamy, Sathyanarayanan
2020-09-28  8:41                                 ` Ethan Zhao
2020-09-28 11:17                                 ` Sinan Kaya [this message]
2020-09-28 12:16                                   ` Sinan Kaya
2020-09-28 17:15                                   ` Kuppuswamy, Sathyanarayanan
2020-09-28 18:02                                     ` Sinan Kaya
2020-09-28 18:25                                       ` Sinan Kaya
2020-09-28 18:32                                         ` Kuppuswamy, Sathyanarayanan
2020-10-12  5:13                                           ` Kuppuswamy, Sathyanarayanan
2020-10-12 14:51                                             ` Sinan Kaya
2020-09-28 12:11                                 ` Sinan Kaya
2020-09-25 23:50                             ` Sinan Kaya
2020-07-24 19:07 sathyanarayanan.kuppuswamy
2020-09-01  5:41 ` Kuppuswamy, Sathyanarayanan
2020-09-22 18:52 ` Bjorn Helgaas

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=a2bbdfed-fb17-51dc-8ae4-55d924c13211@kernel.org \
    --to=okaya@kernel.org \
    --cc=ashok.raj@intel.com \
    --cc=bhelgaas@google.com \
    --cc=helgaas@kernel.org \
    --cc=jay.vosburgh@canonical.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=sathyanarayanan.kuppuswamy@linux.intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PCI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pci/0 linux-pci/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pci linux-pci/ https://lore.kernel.org/linux-pci \
		linux-pci@vger.kernel.org
	public-inbox-index linux-pci

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pci


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git