From: Boaz Harrosh <bharrosh@panasas.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>, <keyrings@linux-nfs.org>,
<linux-security-module@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
NFS list <linux-nfs@vger.kernel.org>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
"Bhamare, Sachin" <sbhamare@panasas.com>,
David Howells <dhowells@redhat.com>,
Eric Paris <eparis@redhat.com>,
"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
Kay Sievers <kay.sievers@vrfy.org>,
James Morris <jmorris@namei.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Greg Kroah-Hartman <gregkh@suse.de>
Subject: Re: [PATCHSET 0/4] kmod: Optional timeout on the wait in call_usermodehelper_exec
Date: Wed, 21 Mar 2012 17:18:01 -0700 [thread overview]
Message-ID: <4F6A6FB9.7010508@panasas.com> (raw)
In-Reply-To: <20120321153519.GB30250@kroah.com>
On 03/21/2012 08:35 AM, Greg KH wrote:
> On Tue, Mar 20, 2012 at 04:18:49PM -0700, Boaz Harrosh wrote:
>> Andrew Hi
>>
>> I'm picking on you because I don't have any one else to pick on.
>> The 3 first patches here, are just good for today. Please see if
>> you would like to take them? or tell me who should take them?
>>
>> The 4th patch is an RFC, which got me looking into this.
>>
>> My motivation is that I added yet another Kernel dependency on the
>> call_usermodehelper() function and am not completely happy with the
>> error case of having the user-mode program stuck forever. In such
>> case I would like the Kernel part to timeout and properly error recover
>> and clean up. So therefor the proposed 4th patch.
>
> What is this new use of call_usermodhelper that you are doing this work
> for? Ideally, you never want to make this call, as it's slow and messy,
> as you have found out. Is there an in-kernel user that you have
> recently added?
>
> thanks,
>
> greg k-h
I agree hence my comment in the 4th patch:
"In the blasphemous occasions that a the Kernel must call a user-mode program"
I have added a new caller, to the nfs/objectlayoutdriver.ko that uses this
facility for auto-login into osd-targets (iscsi-targets) when new are requested
by the filesystem. This auto-login facility is mandated by the pnfs-objects
standard because in a large cluster filesystems for which pnfs was invented, storage
devices break and changed everyday, and a manual login by every client is not
feasible.
You can see this patch as posted to the mailing list here:
http://article.gmane.org/gmane.linux.nfs/48024/match=login
[title: pnfs-obj: autologin: Add support for protocol autologin]
It works very well and was heavily tested, with all error scenarios, but
the theoretical possibility that the user-mode program can be stuck forever
bothers me and I would like to do something about it. With this patch the
Kernel can recover cleanly and continue. I have actually tested this part
and it works as expected.
Thanks
Boaz
next prev parent reply other threads:[~2012-03-22 0:19 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-20 23:18 [PATCHSET 0/4] kmod: Optional timeout on the wait in call_usermodehelper_exec Boaz Harrosh
2012-03-20 23:23 ` [PATCH 1/4] kmod: Un-export call_usermodehelper_freeinfo() Boaz Harrosh
2012-03-20 23:26 ` [PATCH 2/4] kmod: Convert two call sites to call_usermodehelper_fns() Boaz Harrosh
2012-03-22 3:00 ` James Morris
2012-03-20 23:28 ` [PATCH 3/4] kmod: Move call_usermodehelper_fns() to .c file and unexport it's helpers Boaz Harrosh
2012-03-20 23:32 ` [RFC 4/4] {RFC} kmod.c: Add new call_usermodehelper_timeout() API Boaz Harrosh
2012-03-22 2:44 ` Boaz Harrosh
2012-03-22 2:48 ` Boaz Harrosh
2012-03-22 2:52 ` Boaz Harrosh
2012-03-22 11:48 ` [RFC 4/4] {RFC} kmod.c: Add new call_usermodehelper_timeout()API Tetsuo Handa
2012-03-22 14:27 ` [RFC 4/4] {RFC} kmod.c: Add new call_usermodehelper_timeout() API Oleg Nesterov
2012-03-22 14:42 ` Oleg Nesterov
2012-03-22 19:08 ` Boaz Harrosh
2012-03-22 22:16 ` [RFC 4/4] {RFC} kmod.c: Add new call_usermodehelper_timeout()API Tetsuo Handa
2012-03-23 4:48 ` Boaz Harrosh
2012-03-23 5:23 ` Tetsuo Handa
2012-03-23 16:30 ` Oleg Nesterov
2012-03-23 13:34 ` [RFC 4/4] {RFC} kmod.c: Add new call_usermodehelper_timeout() API Oleg Nesterov
2012-03-21 15:35 ` [PATCHSET 0/4] kmod: Optional timeout on the wait in call_usermodehelper_exec Greg KH
2012-03-22 0:18 ` Boaz Harrosh [this message]
2012-03-22 0:31 ` Myklebust, Trond
2012-03-22 1:18 ` Boaz Harrosh
2012-03-27 1:57 ` [PATCHSET 0/6 version 2] " Boaz Harrosh
2012-03-27 2:00 ` [PATCH 1/6] kmod: Unexport call_usermodehelper_freeinfo() Boaz Harrosh
2012-03-27 2:02 ` [PATCH 2/6] kmod: Convert two call sites to call_usermodehelper_fns() Boaz Harrosh
2012-03-27 2:04 ` [PATCH 3/6] kmod: Move call_usermodehelper_fns() to .c file and unexport all it's helpers Boaz Harrosh
2012-03-27 2:06 ` [PATCH 4/6 OPTION-A] completion: Add new wait_for_completion_timeout_state Boaz Harrosh
2012-03-27 2:33 ` [PATCH 4/6 OPTION-A version 3] " Boaz Harrosh
2012-03-27 8:11 ` Peter Zijlstra
2012-03-28 18:19 ` Boaz Harrosh
2012-03-28 18:25 ` Peter Zijlstra
2012-03-28 17:38 ` Oleg Nesterov
2012-03-27 2:09 ` [PATCH 4/6 option-B] kmod: add new wait_for_completion_timeout_state() helper Boaz Harrosh
2012-03-27 2:13 ` [PATCH 5/6] kmod: Add new call_usermodehelper_timeout() API Boaz Harrosh
2012-03-27 15:43 ` Oleg Nesterov
2012-03-28 17:04 ` Oleg Nesterov
2012-03-27 2:15 ` [PATCH 6/6] kmod: optional: Convert the use of xchg to a kref Boaz Harrosh
2012-03-28 16:35 ` Oleg Nesterov
2012-03-27 21:07 ` [PATCHSET 0/6 version 2] kmod: Optional timeout on the wait in call_usermodehelper_exec Andrew Morton
2012-03-28 20:19 ` Oleg Nesterov
2012-03-28 21:42 ` Boaz Harrosh
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