linux-kernel - Re: [PATCH] soc: fsl: guts: us devm_kstrdup

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Message-ID: <20181222075944.GA26155@osadl.at>
Date:   Sat, 22 Dec 2018 08:59:44 +0100
From:   Nicholas Mc Guire <der.herr@...r.at>
To:     Scott Wood <oss@...error.net>
Cc:     Nicholas Mc Guire <hofrat@...dl.org>, Li Yang <leoyang.li@....com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] soc: fsl: guts: us devm_kstrdup_const() for RO data

On Fri, Dec 21, 2018 at 08:29:56PM -0600, Scott Wood wrote:
> On Fri, 2018-12-07 at 09:22 +0100, Nicholas Mc Guire wrote:
> > devm_kstrdup() may return NULL if internal allocation failed, but
> > as  machine  is from the device tree, and thus RO, devm_kstrdup_const()
> > can be used here, which will only copy the reference.
> 
> Is it really going to only copy the reference?  That would require that
> is_kernel_rodata(machine) be true, which it shouldn't be since it's not part
> of the kernel image.
>
I had tried to figure out what is RO and what not but was not 
able to determine that - from the discussion it seemed that the
assumption of RO is correct though I did not ask if it would
satisfy is_kernel_rodata() so that explains the incorrect assertion.
see https://lkml.org/lkml/2018/12/6/42
So then the only option is to check the return and cleanup
on allocation failure as the orriginal patch proposed.

thanks for clearifying this !
hofrat