All of lore.kernel.org
 help / color / mirror / Atom feed
From: Keith Busch <keith.busch@intel.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
	Linux PCI <linux-pci@vger.kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Sinan Kaya <okaya@kernel.org>, Thomas Tai <thomas.tai@oracle.com>,
	poza@codeaurora.org, Lukas Wunner <lukas@wunner.de>,
	Christoph Hellwig <hch@lst.de>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 00/12] error handling and pciehp maintenance
Date: Tue, 6 Nov 2018 09:47:52 -0700	[thread overview]
Message-ID: <20181106164751.GA6217@localhost.localdomain> (raw)
In-Reply-To: <20181106163400.GA21193@e107981-ln.cambridge.arm.com>

On Tue, Nov 06, 2018 at 04:34:08PM +0000, Lorenzo Pieralisi wrote:
> The question is whether we really need to dynamically patch the kernel
> with ftrace to achieve what that patch does.
> 
> Furthermore, it would also be good to report what bugs we are actually
> fixing, from what you are writing falling back to the current method if
> !DYNAMIC_FTRACE_WITH_REGS is broken in many ways and I would start with
> fixing the current behaviour with something that does not depend on arch
> features that may not even be implemented.

There are two problems with the current method:

  1. It may dereference pci_dev after it was freed
  2. The pci_dev's children inherit its fake pci_bus's ops on
     enumeration

Both result in kernel panic.

The dynamic kernel patch just seemed like a cool way to inject errors
without messing with the driver's structures. But if there's a more
elegant way to do it, I'm all for it.

WARNING: multiple messages have this Message-ID (diff)
From: keith.busch@intel.com (Keith Busch)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 00/12] error handling and pciehp maintenance
Date: Tue, 6 Nov 2018 09:47:52 -0700	[thread overview]
Message-ID: <20181106164751.GA6217@localhost.localdomain> (raw)
In-Reply-To: <20181106163400.GA21193@e107981-ln.cambridge.arm.com>

On Tue, Nov 06, 2018 at 04:34:08PM +0000, Lorenzo Pieralisi wrote:
> The question is whether we really need to dynamically patch the kernel
> with ftrace to achieve what that patch does.
> 
> Furthermore, it would also be good to report what bugs we are actually
> fixing, from what you are writing falling back to the current method if
> !DYNAMIC_FTRACE_WITH_REGS is broken in many ways and I would start with
> fixing the current behaviour with something that does not depend on arch
> features that may not even be implemented.

There are two problems with the current method:

  1. It may dereference pci_dev after it was freed
  2. The pci_dev's children inherit its fake pci_bus's ops on
     enumeration

Both result in kernel panic.

The dynamic kernel patch just seemed like a cool way to inject errors
without messing with the driver's structures. But if there's a more
elegant way to do it, I'm all for it.

  reply	other threads:[~2018-11-06 16:50 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-18 23:58 [PATCH 00/12] error handling and pciehp maintenance Keith Busch
2018-09-18 23:58 ` [PATCH 01/12] PCI: Set PCI bus accessors to noinline Keith Busch
2018-09-18 23:58 ` [PATCH 02/12] PCI/AER: Covertly inject errors Keith Busch
2018-09-18 23:58 ` [PATCH 03/12] PCI/AER: Reuse existing service device lookup Keith Busch
2018-09-18 23:58 ` [PATCH 04/12] PCI/AER: Abstract AER interrupt handling Keith Busch
2018-09-18 23:58 ` [PATCH 05/12] PCI/AER: Remove dead code Keith Busch
2018-09-18 23:58 ` [PATCH 06/12] PCI/AER: Remove error source from aer struct Keith Busch
2018-09-18 23:58 ` [PATCH 07/12] PCI/AER: Use kfifo for tracking events Keith Busch
2018-09-18 23:58 ` [PATCH 08/12] PCI/AER: Use kfifo helper inserting locked elements Keith Busch
2018-09-18 23:58 ` [PATCH 09/12] PCI/AER: Don't read upstream ports below fatal errors Keith Busch
2018-09-18 23:58 ` [PATCH 10/12] PCI/AER: Use threaded IRQ for bottom half Keith Busch
2018-09-18 23:58 ` [PATCH 11/12] PCI/AER: Use managed resource allocations Keith Busch
2018-09-19 16:29   ` Sinan Kaya
2018-09-19 17:25     ` Keith Busch
2018-09-19 17:36       ` Sinan Kaya
2018-09-25  1:13   ` Benjamin Herrenschmidt
2018-09-25 14:17     ` Keith Busch
2018-09-18 23:58 ` [PATCH 12/12] PCI/pciehp: Use device managed allocations Keith Busch
2018-09-19 15:11   ` Sinan Kaya
2018-09-19 16:17     ` Keith Busch
2018-09-22 18:10   ` Lukas Wunner
2018-09-24 23:43     ` Bjorn Helgaas
2018-09-25  7:13       ` Lukas Wunner
2018-10-04 21:40 ` [PATCH 00/12] error handling and pciehp maintenance Bjorn Helgaas
2018-10-04 22:11   ` Keith Busch
2018-10-05 17:31     ` Bjorn Helgaas
2018-10-05 17:31       ` Bjorn Helgaas
2018-10-08 16:18       ` Keith Busch
2018-10-08 16:18         ` Keith Busch
2018-10-08 17:23         ` Bjorn Helgaas
2018-10-08 17:23           ` Bjorn Helgaas
2018-11-06 16:34         ` Lorenzo Pieralisi
2018-11-06 16:34           ` Lorenzo Pieralisi
2018-11-06 16:47           ` Keith Busch [this message]
2018-11-06 16:47             ` Keith Busch
2018-11-06 17:21             ` Lorenzo Pieralisi
2018-11-06 17:21               ` Lorenzo Pieralisi
2018-11-06 17:26               ` Keith Busch
2018-11-06 17:26                 ` Keith Busch
2018-10-09 16:03       ` Will Deacon
2018-10-09 16:03         ` Will Deacon

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=20181106164751.GA6217@localhost.localdomain \
    --to=keith.busch@intel.com \
    --cc=benh@kernel.crashing.org \
    --cc=bhelgaas@google.com \
    --cc=catalin.marinas@arm.com \
    --cc=hch@lst.de \
    --cc=helgaas@kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=lorenzo.pieralisi@arm.com \
    --cc=lukas@wunner.de \
    --cc=mika.westerberg@linux.intel.com \
    --cc=okaya@kernel.org \
    --cc=poza@codeaurora.org \
    --cc=thomas.tai@oracle.com \
    --cc=will.deacon@arm.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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.