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

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Message-ID: <2w3cvyef33vgcg3aurb4n6q7go2p63cofz3a4pbdat53fqldee@jwzcj5dssgvh>
Date:   Mon, 31 Jul 2023 17:30:00 +0530
From:   Gautam Menghani <Gautam.Menghani@...ux.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>
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

On Sat, Jul 29, 2023 at 08:54:26PM +1000, Michael Ellerman wrote:
> 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

Thanks for the response. I've sent a v2 here - 
lore.kernel.org/linuxppc-dev/20230731115543.36991-1-gautam@...ux.ibm.com/T/#u

Thanks,
Gautam