All of lore.kernel.org
 help / color / mirror / Atom feed
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>,
	kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [Q] Why does kexec use device_shutdown rather than ubind them
Date: Fri, 17 Jan 2014 16:59:13 +1100	[thread overview]
Message-ID: <1389938353.7406.22.camel@pasglop> (raw)
In-Reply-To: <871u07fbvl.fsf@xmission.com>

On Thu, 2014-01-16 at 20:52 -0800, Eric W. Biederman wrote:
> 
> I think we have largely survied until now because kdump is so popular
> and kdump winds up having to reinitialize devices from any random
> state.

kdump also doesn't care too much if the device is still DMA'ing to the
old kernel memory :-)

> But like I said I am all for reducing the burden on device driver
> developers.

Right. I'm experimenting with a variant of device_shutdown() that tries
remove() first and if it doesn't exist and shutdown() does, call that
(is that ever the case ?). I'm keeping this kexec-specific for now.

I'll try to hammer that on some of our machines see if it breaks
anything, I think it's a much better approach for kexec.

As for actual machine shutdown, we *might* have some corner cases where
shutdown is actually different from remove for good reasons, so that
will have to be investigated a bit more in depth.

I'll post my results when I have them.

Cheers,
Ben.



_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Matthew Garrett <matthew.garrett@nebula.com>,
	Vivek Goyal <vgoyal@redhat.com>,
	kexec@lists.infradead.org
Subject: Re: [Q] Why does kexec use device_shutdown rather than ubind them
Date: Fri, 17 Jan 2014 16:59:13 +1100	[thread overview]
Message-ID: <1389938353.7406.22.camel@pasglop> (raw)
In-Reply-To: <871u07fbvl.fsf@xmission.com>

On Thu, 2014-01-16 at 20:52 -0800, Eric W. Biederman wrote:
> 
> I think we have largely survied until now because kdump is so popular
> and kdump winds up having to reinitialize devices from any random
> state.

kdump also doesn't care too much if the device is still DMA'ing to the
old kernel memory :-)

> But like I said I am all for reducing the burden on device driver
> developers.

Right. I'm experimenting with a variant of device_shutdown() that tries
remove() first and if it doesn't exist and shutdown() does, call that
(is that ever the case ?). I'm keeping this kexec-specific for now.

I'll try to hammer that on some of our machines see if it breaks
anything, I think it's a much better approach for kexec.

As for actual machine shutdown, we *might* have some corner cases where
shutdown is actually different from remove for good reasons, so that
will have to be investigated a bit more in depth.

I'll post my results when I have them.

Cheers,
Ben.



  reply	other threads:[~2014-01-17  5:59 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-17  3:39 [Q] Why does kexec use device_shutdown rather than ubind them Benjamin Herrenschmidt
2014-01-17  3:39 ` Benjamin Herrenschmidt
2014-01-17  4:52 ` Eric W. Biederman
2014-01-17  4:52   ` Eric W. Biederman
2014-01-17  5:59   ` Benjamin Herrenschmidt [this message]
2014-01-17  5:59     ` Benjamin Herrenschmidt
2014-01-17 14:13     ` Vivek Goyal
2014-01-17 14:13       ` Vivek Goyal
2014-01-17 15:57       ` Sumner, William
2014-01-17 15:57         ` Sumner, William
2014-01-17 15:57         ` Sumner, William
2014-01-17 21:00       ` Benjamin Herrenschmidt
2014-01-17 21:00         ` Benjamin Herrenschmidt

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=1389938353.7406.22.camel@pasglop \
    --to=benh@kernel.crashing.org \
    --cc=akpm@linux-foundation.org \
    --cc=ebiederm@xmission.com \
    --cc=kexec@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=matthew.garrett@nebula.com \
    --cc=torvalds@linux-foundation.org \
    --cc=vgoyal@redhat.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.