From: Greg KH <gregkh@linuxfoundation.org>
To: Khalid Aziz <khalid.aziz@oracle.com>
Cc: cl91tp@gmail.com, gnomes@lxorguk.ukuu.org.uk,
indou.takao@jp.fujitsu.com, mjg59@srcf.ucam.org,
linux-pci@vger.kernel.org, kexec@lists.infradead.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
f.otti@gmx.at, khlebnikov@openvz.org,
"Eric W. Biederman" <ebiederm@xmission.com>,
jility09@gmail.com, bhelgaas@google.com, tianyu.lan@intel.com
Subject: Re: [PATCH] PCI: Clear Bus Master bit only on kexec reboot
Date: Wed, 27 Nov 2013 13:22:27 -0800 [thread overview]
Message-ID: <20131127212227.GA31237@kroah.com> (raw)
In-Reply-To: <52964F2C.1020803@oracle.com>
On Wed, Nov 27, 2013 at 12:59:40PM -0700, Khalid Aziz wrote:
> On 11/27/2013 12:38 PM, ebiederm@xmission.com wrote:
> >Khalid Aziz <khalid.aziz@oracle.com> writes:
> >
> >>Add a flag to tell the PCI subsystem that kernel is shutting down
> >>in prepapration to kexec a kernel. Add code in PCI subsystem to use
> >>this flag to clear Bus Master bit on PCI devices only in case of
> >>kexec reboot. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=63861
> >>and avoids any other issues caused by clearing Bus Master bit on PCI
> >>devices in normal shutdown path. This patch is based on discussion at
> >>http://marc.info/?l=linux-pci&m=138425645204355&w=2
> >
> >Scratches head.
> >
> >Given that most devices already call pci_disable_device which clears the
> >bus master bit how does this change anything meaningful?
> >
> >Is is the problem here that most drivers are lazy and have a noop
> >shutdown method?
>
> Yes, that is exactly the problem.
Then fix the drivers please. It's not as if you don't have access to
the source for them all...
greg k-h
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WARNING: multiple messages have this Message-ID (diff)
From: Greg KH <gregkh@linuxfoundation.org>
To: Khalid Aziz <khalid.aziz@oracle.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
bhelgaas@google.com, cl91tp@gmail.com, tianyu.lan@intel.com,
khlebnikov@openvz.org, gnomes@lxorguk.ukuu.org.uk,
indou.takao@jp.fujitsu.com, jility09@gmail.com, f.otti@gmx.at,
mjg59@srcf.ucam.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org, kexec@lists.infradead.org,
stable@vger.kernel.org
Subject: Re: [PATCH] PCI: Clear Bus Master bit only on kexec reboot
Date: Wed, 27 Nov 2013 13:22:27 -0800 [thread overview]
Message-ID: <20131127212227.GA31237@kroah.com> (raw)
In-Reply-To: <52964F2C.1020803@oracle.com>
On Wed, Nov 27, 2013 at 12:59:40PM -0700, Khalid Aziz wrote:
> On 11/27/2013 12:38 PM, ebiederm@xmission.com wrote:
> >Khalid Aziz <khalid.aziz@oracle.com> writes:
> >
> >>Add a flag to tell the PCI subsystem that kernel is shutting down
> >>in prepapration to kexec a kernel. Add code in PCI subsystem to use
> >>this flag to clear Bus Master bit on PCI devices only in case of
> >>kexec reboot. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=63861
> >>and avoids any other issues caused by clearing Bus Master bit on PCI
> >>devices in normal shutdown path. This patch is based on discussion at
> >>http://marc.info/?l=linux-pci&m=138425645204355&w=2
> >
> >Scratches head.
> >
> >Given that most devices already call pci_disable_device which clears the
> >bus master bit how does this change anything meaningful?
> >
> >Is is the problem here that most drivers are lazy and have a noop
> >shutdown method?
>
> Yes, that is exactly the problem.
Then fix the drivers please. It's not as if you don't have access to
the source for them all...
greg k-h
next prev parent reply other threads:[~2013-11-27 21:22 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-27 19:18 [PATCH] PCI: Clear Bus Master bit only on kexec reboot Khalid Aziz
2013-11-27 19:18 ` Khalid Aziz
2013-11-27 19:24 ` Matthew Garrett
2013-11-27 19:24 ` Matthew Garrett
2013-11-27 19:48 ` Khalid Aziz
2013-11-27 19:48 ` Khalid Aziz
2013-11-27 19:53 ` Matthew Garrett
2013-11-27 19:53 ` Matthew Garrett
2013-11-27 19:38 ` Eric W. Biederman
2013-11-27 19:38 ` Eric W. Biederman
2013-11-27 19:59 ` Khalid Aziz
2013-11-27 19:59 ` Khalid Aziz
2013-11-27 21:22 ` Greg KH [this message]
2013-11-27 21:22 ` Greg KH
2013-11-27 21:53 ` Matthew Garrett
2013-11-27 21:53 ` Matthew Garrett
2013-11-27 22:01 ` Greg KH
2013-11-27 22:01 ` Greg KH
2013-11-27 22:07 ` Matthew Garrett
2013-11-27 22:07 ` Matthew Garrett
2013-11-27 22:18 ` Khalid Aziz
2013-11-27 22:18 ` Khalid Aziz
2013-11-28 14:15 ` One Thousand Gnomes
2013-11-28 14:15 ` One Thousand Gnomes
2013-11-27 19:39 ` Greg KH
2013-11-27 19:39 ` Greg KH
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