linux-kernel - Re: [PATCH] arch/powerpc: Remove unnecessary endian conversion code in XICS

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Message-ID: <873517dm3h.fsf@mail.lhotse>
Date:   Sat, 29 Jul 2023 20:54:26 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Gautam Menghani <Gautam.Menghani@...ux.ibm.com>
Cc:     Gautam Menghani <gautam@...ux.ibm.com>, npiggin@...il.com,
        christophe.leroy@...roup.eu, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arch/powerpc: Remove unnecessary endian conversion code
 in XICS

Gautam Menghani <Gautam.Menghani@...ux.ibm.com> writes:
> On Thu, Jul 06, 2023 at 05:50:57PM +1000, Jordan Niethe wrote:
>> On 30/6/23 3:56 pm, Gautam Menghani wrote:
>> > Remove an unnecessary piece of code that does an endianness conversion but
>> > does not use the result. The following warning was reported by Clang's
>> > static analyzer:
>> > 
>> > arch/powerpc/sysdev/xics/ics-opal.c:114:2: warning: Value stored to
>> > 'server' is never read [deadcode.DeadStores]
>> >          server = be16_to_cpu(oserver);
>> > 
>> > As the result of endianness conversion is never used, delete the line
>> > and fix the warning.
>> > 
>> > Signed-off-by: Gautam Menghani <gautam@...ux.ibm.com>
>> 
>> 'server' was used as a parameter to opal_get_xive() in commit 5c7c1e9444d8
>> ("powerpc/powernv: Add OPAL ICS backend") when it was introduced. 'server'
>> was also used in an error message for the call to opal_get_xive().
>> 
>> 'server' was always later set by a call to ics_opal_mangle_server() before
>> being used.
>> 
>> Commit bf8e0f891a32 ("powerpc/powernv: Fix endian issues in OPAL ICS
>> backend") used a new variable 'oserver' as the parameter to opal_get_xive()
>> instead of 'server' for endian correctness. It also removed 'server' from
>> the error message for the call to opal_get_xive().
>> 
>> It was commit bf8e0f891a32 that added the unnecessary conversion and never
>> used the result.
>> 
>> Reviewed-by: Jordan Niethe <jniethe5@...il.com>
>> 
>
> Hello Michael, 
>
> Do you have any more questions on this patch or is it good to go?

I was expecting you'd send a v2 with the changelog updated to include
all the extra detail Jordan added. I think it should also be tagged as
Fixes: bf8e0f891a32.

cheers