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From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Luis Chamberlain <mcgrof@kernel.org>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Christoph Hellwig <hch@infradead.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	ast@kernel.org, axboe@kernel.dk, bfields@fieldses.org,
	bridge@lists.linux-foundation.org, chainsaw@gentoo.org,
	christian.brauner@ubuntu.com, chuck.lever@oracle.com,
	davem@davemloft.net, dhowells@redhat.com,
	gregkh@linuxfoundation.org, jarkko.sakkinen@linux.intel.com,
	jmorris@namei.org, josh@joshtriplett.org, keescook@chromium.org,
	keyrings@vger.kernel.org, kuba@kernel.org,
	lars.ellenberg@linbit.com, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	nikolay@cumulusnetworks.com, philipp.reisner@linbit.com,
	ravenexp@gmail.com, roopa@cumulusnetworks.com, serge@hallyn.com,
	slyfox@gentoo.org, viro@zeniv.linux.org.uk,
	yangtiezhu@loongson.cn, netdev@vger.kernel.org,
	markward@linux.ibm.com, linux-s390 <linux-s390@vger.kernel.org>
Subject: Re: linux-next: umh: fix processed error when UMH_WAIT_PROC is used seems to break linux bridge on s390x (bisected)
Date: Wed, 1 Jul 2020 17:48:48 +0200	[thread overview]
Message-ID: <f9f0f868-e511-990a-2a74-1806ac0cb7ac@de.ibm.com> (raw)
In-Reply-To: <20200701153859.GT4332@42.do-not-panic.com>



On 01.07.20 17:38, Luis Chamberlain wrote:
> On Wed, Jul 01, 2020 at 11:08:57PM +0900, Tetsuo Handa wrote:
>> On 2020/07/01 22:53, Luis Chamberlain wrote:
>>>> Well, it is not br_stp_call_user() but br_stp_start() which is expecting
>>>> to set sub_info->retval for both KWIFEXITED() case and KWIFSIGNALED() case.
>>>> That is, sub_info->retval needs to carry raw value (i.e. without "umh: fix
>>>> processed error when UMH_WAIT_PROC is used" will be the correct behavior).
>>>
>>> br_stp_start() doesn't check for the raw value, it just checks for err
>>> or !err. So the patch, "umh: fix processed error when UMH_WAIT_PROC is
>>> used" propagates the correct error now.
>>
>> No. If "/sbin/bridge-stp virbr0 start" terminated due to e.g. SIGSEGV
>> (for example, by inserting "kill -SEGV $$" into right after "#!/bin/sh" line),
>> br_stp_start() needs to select BR_KERNEL_STP path. We can't assume that
>> /sbin/bridge-stp is always terminated by exit() syscall (and hence we can't
>> ignore KWIFSIGNALED() case in call_usermodehelper_exec_sync()).
> 
> Ah, well that would be a different fix required, becuase again,
> br_stp_start() does not untangle the correct error today really.
> I also I think it would be odd odd that SIGSEGV or another signal 
> is what was terminating Christian's bridge stp call, but let's
> find out!
> 
> Note we pass 0 to the options to wait so the mistake here could indeed
> be that we did not need KWIFSIGNALED(). I was afraid of this prospect...
> as it other implications.
> 
> It means we either *open code* all callers, or we handle this in a
> unified way on the umh. And if we do handle this in a unified way, it
> then begs the question as to *what* do we pass for the signals case and
> continued case. Below we just pass the signal, and treat continued as
> OK, but treating continued as OK would also be a *new* change as well.
> 
> For instance (this goes just boot tested, but Christian if you can
> try this as well that would be appreciated):


Does not help, the bridge stays in DOWN state. 

  reply	other threads:[~2020-07-01 15:49 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-10 15:49 [PATCH 0/5] kmod/umh: a few fixes Luis R. Rodriguez
2020-06-10 15:49 ` [PATCH 1/5] selftests: kmod: Use variable NAME in kmod_test_0001() Luis R. Rodriguez
2020-06-10 15:49 ` [PATCH 2/5] kmod: Remove redundant "be an" in the comment Luis R. Rodriguez
2020-06-10 15:49 ` [PATCH 3/5] test_kmod: Avoid potential double free in trigger_config_run_type() Luis R. Rodriguez
2020-06-10 15:49 ` [PATCH 4/5] umh: fix processed error when UMH_WAIT_PROC is used Luis R. Rodriguez
2020-06-23 14:11   ` linux-next: umh: fix processed error when UMH_WAIT_PROC is used seems to break linux bridge on s390x (bisected) Christian Borntraeger
2020-06-23 14:23     ` Christian Borntraeger
2020-06-24 11:11       ` Christian Borntraeger
2020-06-24 12:05         ` Luis Chamberlain
2020-06-24 13:17           ` Luis Chamberlain
2020-06-24 16:13             ` Luis Chamberlain
2020-06-24 14:43         ` Christoph Hellwig
2020-06-24 15:54           ` Christian Borntraeger
2020-06-24 16:09             ` Luis Chamberlain
2020-06-24 17:58               ` Christian Borntraeger
2020-06-24 18:09                 ` Christian Borntraeger
2020-06-24 18:32                   ` Christian Borntraeger
2020-06-24 18:37                     ` Christian Borntraeger
2020-06-25 13:26                       ` Christian Borntraeger
2020-06-26  2:54                       ` Luis Chamberlain
2020-06-26  5:22                         ` Christian Borntraeger
2020-06-26  9:00                           ` Christoph Hellwig
2020-06-26 11:40                             ` Luis Chamberlain
2020-06-26 11:50                               ` Luis Chamberlain
2020-06-30 17:57                         ` Luis Chamberlain
2020-07-01 10:08                           ` Christian Borntraeger
2020-07-01 13:24                             ` Tetsuo Handa
2020-07-01 13:53                               ` Luis Chamberlain
2020-07-01 14:08                                 ` Tetsuo Handa
2020-07-01 15:38                                   ` Luis Chamberlain
2020-07-01 15:48                                     ` Christian Borntraeger [this message]
2020-07-01 15:58                                       ` Luis Chamberlain
2020-07-01 16:01                                         ` Christian Borntraeger
2020-07-02  4:26                                     ` Tetsuo Handa
2020-07-02 19:46                                       ` Luis Chamberlain
2020-07-03  0:52                                         ` Tetsuo Handa
2020-07-03 13:28                                           ` Luis Chamberlain
2020-07-01 15:26                                 ` Christian Borntraeger
2020-07-01 13:46                             ` Luis Chamberlain
2020-06-10 15:49 ` [PATCH 5/5] selftests: simplify kmod failure value Luis R. Rodriguez
2020-06-18  0:43 ` [PATCH 0/5] kmod/umh: a few fixes Andrew Morton
2020-06-19 20:46   ` Luis Chamberlain
2020-06-19 21:07     ` Luis Chamberlain

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