linux-kernel - Re: [PATCH] powerpc: Use common error handling code in setup_new

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Message-ID: <87bmfofh8y.fsf@concordia.ellerman.id.au>
Date:   Fri, 16 Mar 2018 21:26:53 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
Cc:     SF Markus Elfring <elfring@...rs.sourceforge.net>,
        linuxppc-dev@...ts.ozlabs.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Borislav Petkov <bp@...e.de>,
        Brijesh Singh <brijesh.singh@....com>,
        Josh Sklar <sklar@...ux.vnet.ibm.com>,
        Kees Cook <keescook@...omium.org>,
        Paul Mackerras <paulus@...ba.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] powerpc: Use common error handling code in setup_new_fdt()

Dan Carpenter <dan.carpenter@...cle.com> writes:
> On Wed, Mar 14, 2018 at 06:22:07PM -0300, Thiago Jung Bauermann wrote:
>> SF Markus Elfring <elfring@...rs.sourceforge.net> writes:
>> > From: Markus Elfring <elfring@...rs.sourceforge.net>
>> > Date: Sun, 11 Mar 2018 09:03:42 +0100
>> >
>> > Add a jump target so that a bit of exception handling can be better reused
>> > at the end of this function.
>> >
>> > This issue was detected by using the Coccinelle software.
>> >
>> > Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
>> > ---
>> >  arch/powerpc/kernel/machine_kexec_file_64.c | 28 ++++++++++++----------------
>> >  1 file changed, 12 insertions(+), 16 deletions(-)
>> 
>> I liked it. Thanks!
>> 
>> Reviewed-by: Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
>
> You know that compilers already re-use string constants so this doesn't
> actually save memory?

Sure, but it's still clearer to only have the string appear once in the
code.

> Also we should be preserving the error codes
> instead of always returning -EINVAL.

The error codes come from libfdt code, so they don't necessarily make
sense in the kernel. eg. FDT_ERR_NOSPACE == 3 == ESRCH.

Perhaps we should be trying harder to convert them, but that's a
criticism of the original code not this patch.

cheers