LKML Archive on
help / color / mirror / Atom feed
From: "linux-os \(Dick Johnson\)" <>
To: "Randy Dunlap" <>
Cc: "Pavel Machek" <>, "Andrew Morton" <>,
	"Ingo Molnar" <>, <>,
Subject: Re: [patch] fix emergency reboot: call reboot notifier list if possible
Date: Wed, 24 Jan 2007 12:49:32 -0500	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, 24 Jan 2007, Randy Dunlap wrote:

> On Tue, 23 Jan 2007 19:57:12 +0000 Pavel Machek wrote:
>> Hi!
>>>>> On Wed, Jan 17, 2007 at 10:13:19AM +0100, Ingo Molnar wrote:
>>>>>> we dont call the reboot notifiers during emergency reboot mainly because
>>>>>> it could be called from atomic context and reboot notifiers are a
>>>>>> blocking notifier list. But actually the kernel is often perfectly
>>>>>> reschedulable in this stage, so we could as well process the
>>>>>> reboot_notifier_list.
>>>>> My experience has been that when there has been the need to use this
>>>>> facility, the kernel hasn't been reschedulable. [...]
>>>> this decision is totally automatic - so if your situation happens and
>>>> the kernel isnt reschedulable, then the notifier chain wont be called
>>>> and nothing changes from your perspective. Hm, perhaps this should be
>>>> dependent on CONFIG_PREEMPT, to make sure preempt_count() is reliable?
>>>> but from my perspective this patch fixes a real regression.
>>>> updated patch attached below.
>>> Making it dependent upon CONFIG_PREEMPT seems a bit sucky.  Perhaps pass in
>>> some "you were called from /proc/sysrq-trigger" notification?
>> What about adding 'B' with 'reboot with notifications' meaning?
> if I am reading 'B' vs. 'b' correctly:
> sysrq key codes are currently all lower case only.
> Of course, that could be changed to support upper case.
> That would require sysrq help messages in a different format
> (currently the keycode for the action is Capitalized, e.g.,
> b => reBoot).  And I suspect that it would allow some users to
> enter b vs. B or B vs. b etc. unintentionally.
> In any case, the sysrq_key_table could easily fill up soon,
> so we may be force to support UpperCase codes.
> ---
> ~Randy

The you can take the lower scan-code and AND it with 95 (decimal)
before the test. That will allow all A-z codes to work (not numbers,
though). They get compared with the upper-case.

Dick Johnson
Penguin : Linux version on an i686 machine (5592.59 BogoMips).
New book:

The information transmitted in this message is confidential and may be privileged.  Any review, retransmission, dissemination, or other use of this information by persons or entities other than the intended recipient is prohibited.  If you are not the intended recipient, please notify Analogic Corporation immediately - by replying to this message or by sending an email to - and destroy all copies of this information, including any attachments, without reading or disclosing them.

Thank you.

  reply	other threads:[~2007-01-24 17:49 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-17  9:13 Ingo Molnar
2007-01-17  9:22 ` Russell King
2007-01-17  9:39   ` Ingo Molnar
2007-01-17 10:03     ` Andrew Morton
2007-01-17 10:25       ` Ingo Molnar
2007-01-23 19:57       ` Pavel Machek
2007-01-24 16:30         ` Randy Dunlap
2007-01-24 17:49           ` linux-os (Dick Johnson) [this message]
2007-01-17  9:51 ` [patch] KVM: do VMXOFF upon reboot Ingo Molnar
2007-01-17 10:02   ` Ingo Molnar
2007-01-21 10:17     ` Avi Kivity

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:

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

  git send-email \ \ \ \ \ \ \ \ \
    --subject='Re: [patch] fix emergency reboot: call reboot notifier list if possible' \

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

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).