linux-kernel - [PATCH 0/1] params: don't ignore the rest of cmdline if parse

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Date:	Tue, 25 Aug 2015 17:18:26 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH 0/1] params: don't ignore the rest of cmdline if
	parse_one() fails

On 08/25, Rusty Russell wrote:
>
> Oleg Nesterov <oleg@...hat.com> writes:
> > On 08/24, Oleg Nesterov wrote:
> >>
> >> I booted the kernel with the additional patch below, and nothing bad has
> >> happened,
> >
> > Until I tried reboot it once with "locktorture.verbose=true" paramater.
> > It didn't boot.
> >
> > This is because parse_args() just aborts after it hits the error, so other
> > arguments at the same initcall level are simply ignored.
> >
> > Fixed by the patch below, but I simply can't believe nobody hit this (imo)
> > bug before.
> >
> > Why does parse_args() do this?? I simply can't understand why parse_args()
> > adds more random and hard-to-understand problems if one of the args ("=true"
> > in this particular case) is wrong.
> >
> > Yes, the patch below is probably oversimplified / incomplete but imho the
> > current behaviour is confusing. At least I was greatly confused ;) At least
> > (I think) it makes sense to let the user know that the rest of command line
> > was probably ignored.
>
> This is nice, but please save and return the error properly; modules need
> this too.

OK, thanks, please see the patch.

> I think nobody hit this before because they notice that they screwed up
> the commandline and it didn't boot.

Yes, I didn't know parse_args() works this way. Besides, I didn't notice
the "invalid for parameter" error message on the serial console, so I
thought that the kernel panic was somehow caused by the patch I tried
to test.

Oleg.

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