From: Seiji Aguchi <seiji.aguchi@hds.com>
To: "Luck, Tony" <tony.luck@intel.com>, Don Zickus <dzickus@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Matthew Garrett <mjg@redhat.com>, Vivek Goyal <vgoyal@redhat.com>,
"Chen, Gong" <gong.chen@intel.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"Brown, Len" <len.brown@intel.com>,
"'ying.huang@intel.com'" <'ying.huang@intel.com'>,
"'ak@linux.intel.com'" <'ak@linux.intel.com'>,
"'hughd@chromium.org'" <'hughd@chromium.org'>,
"'mingo@elte.hu'" <'mingo@elte.hu'>,
"jmorris@namei.org" <jmorris@namei.org>,
"a.p.zijlstra@chello.nl" <a.p.zijlstra@chello.nl>,
"namhyung@gmail.com" <namhyung@gmail.com>,
"dle-develop@lists.sourceforge.net"
<dle-develop@lists.sourceforge.net>,
Satoru Moriya <satoru.moriya@hds.com>
Subject: RE: [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop()
Date: Thu, 5 Jan 2012 15:10:25 -0500 [thread overview]
Message-ID: <5C4C569E8A4B9B42A84A977CF070A35B2C5827B01D@USINDEVS01.corp.hds.com> (raw)
In-Reply-To: <3908561D78D1C84285E8C5FCA982C28FBB21@ORSMSX104.amr.corp.intel.com>
>Aren't you worried about the comment about smp_send_stop() not
>being hardened to work in a panic situation?
> /*
> * Note smp_send_stop is the usual smp shutdown function, which
> * unfortunately means it may not be hardened to work in a panic
This comment is wrong because Don improved smp_send_stop() by switching REBOOT_VECTOR to NMI.
And his patch has already merged to linux-next tree.
http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git;a=commitdiff;h=3603a2512f9e69dc87914ba922eb4a0812b21cd6
So, current smp_send_stop() is hardened to work in a panic situation.
I will remove this wrong comment.
Seiji
>-----Original Message-----
>From: Luck, Tony [mailto:tony.luck@intel.com]
>Sent: Thursday, January 05, 2012 2:07 PM
>To: Seiji Aguchi; Don Zickus
>Cc: linux-kernel@vger.kernel.org; Matthew Garrett; Vivek Goyal; Chen, Gong; akpm@linux-foundation.org; Brown, Len;
>'ying.huang@intel.com'; 'ak@linux.intel.com'; 'hughd@chromium.org'; 'mingo@elte.hu'; jmorris@namei.org;
>a.p.zijlstra@chello.nl; namhyung@gmail.com; dle-develop@lists.sourceforge.net; Satoru Moriya
>Subject: RE: [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop()
>
>- kmsg_dump(KMSG_DUMP_PANIC);
>-
> /*
> * Note smp_send_stop is the usual smp shutdown function, which
> * unfortunately means it may not be hardened to work in a panic
>@@ -117,6 +115,8 @@ void panic(const char *fmt, ...)
> */
> smp_send_stop();
>
>+ kmsg_dump(KMSG_DUMP_PANIC);
>+
>
>Aren't you worried about the comment about smp_send_stop() not
>being hardened to work in a panic situation?
>
>If it does work - we are clearly much better off moving the
>kmsg_dump() call down like this. It makes life much simpler
>and cleaner to work with just one running cpu.
>
>But if something goes wrong - we might not see the dump at all!
>
>How do we compare these cases and decide that it is better to
>trust that smp_send_stop() will return?
>
>-Tony
next prev parent reply other threads:[~2012-01-05 20:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-05 17:35 [RFC][PATCH v4 -next 0/4] Make pstore/kmsg_dump run after stopping other cpus in panic path Seiji Aguchi
2012-01-05 17:36 ` [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop() Seiji Aguchi
2012-01-05 19:06 ` Luck, Tony
2012-01-05 20:10 ` Seiji Aguchi [this message]
2012-01-05 21:01 ` Don Zickus
2012-01-09 17:59 ` Seiji Aguchi
2012-01-10 3:06 ` Chen Gong
2012-01-10 20:29 ` Seiji Aguchi
2012-01-11 7:28 ` Chen Gong
2012-01-11 17:25 ` Don Zickus
2012-01-11 22:22 ` Luck, Tony
2012-01-13 22:50 ` Seiji Aguchi
[not found] ` <32727E9A83EE9A42A1F0906295A3A77B2C78F49973@USINDEVS01.corp.hds.com>
2012-01-19 20:58 ` Seiji Aguchi
2012-01-20 17:56 ` Luck, Tony
2012-02-03 17:18 ` Don Zickus
2012-02-03 22:32 ` Luck, Tony
2012-02-03 22:57 ` Don Zickus
2012-02-08 20:19 ` Don Zickus
2012-02-08 21:28 ` Luck, Tony
2012-02-08 22:48 ` Don Zickus
2012-02-08 22:56 ` Seiji Aguchi
2012-01-05 17:38 ` [RFC][PATCH v4 -next 2/4] Skip spin_locks in panic case and Add WARN_ON() Seiji Aguchi
2012-01-05 17:39 ` [RFC][PATCH v4 -next 3/4]Skip subsequent kmsg_dump() function calls in panic path Seiji Aguchi
2012-01-05 17:41 ` [RFC][PATCH v4 -next 4/4] Skip spin_lock of efi_pstore_write() in panic case Seiji Aguchi
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