linux-kernel - Re: [PATCH -next] cacheinfo: Correctly handle new acpi_get_cache

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Message-ID: <20230124135045.ntl2nhf2oehdc7mu@bogus>
Date:   Tue, 24 Jan 2023 13:50:45 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Conor Dooley <conor.dooley@...rochip.com>
Cc:     Pierre Gondois <pierre.gondois@....com>,
        linux-kernel@...r.kernel.org, Dan Carpenter <error27@...il.com>,
        Sudeep Holla <sudeep.holla@....com>,
        kernel test robot <lkp@...el.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Gavin Shan <gshan@...hat.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH -next] cacheinfo: Correctly handle new
 acpi_get_cache_info() prototype

On Tue, Jan 24, 2023 at 01:31:06PM +0000, Conor Dooley wrote:
> Hey!
> 
> On Tue, Jan 24, 2023 at 01:34:46PM +0100, Pierre Gondois wrote:
> > commit bd500361a937 ("ACPI: PPTT: Update acpi_find_last_cache_level()
> > to acpi_get_cache_info()")
> > updates the function acpi_get_cache_info().
> > 
> > If CONFIG_ACPI_PPTT is not defined, acpi_get_cache_info() doesn't
> > update its *levels and *split_levels parameters and returns 0.
> > This can lead to a faulty behaviour.
> > 
> > Make acpi_get_cache_info() return an error code if CONFIG_ACPI_PPTT
> > is not defined. Initialize levels and split_levels before passing
> > their address to acpi_get_cache_info().
> > 
> > Also, in init_cache_level():
> 
> Hmm...
> 
> > - commit e75d18cecbb3 ("arm64: cacheinfo: Fix incorrect
> >   assignment of signed error value to unsigned fw_level")
> >   checks the fw_level value in init_cache_level() in case
> >   the value is negative. Remove this check as the error code
> >   is not returned through fw_level anymore.
> > - if no PPTT is present or CONFIG_ACPI_PPTT is not defined,
> >   it is still possible to use the cache information from clidr_el1.
> >   Instead of aborting if acpi_get_cache_info() returns an error
> >   code, just continue.
> 
> To be honest, these feel like entirely separate things that should be
> in different patches. You've got:
> - Dan's smatch fixes
> - a redundant check being removed
> - a behaviour change for if acpi_get_cache_info() returns an error
>

I am not too fussy about it, but for sure it would be cleaner for sure.

> > Reported-by: Dan Carpenter <error27@...il.com>
> > Reported-by: kernel test robot <lkp@...el.com>
>
> How about Link: to the LKP/Dan's report?
> Link: https://lore.kernel.org/all/Y86iruJPuwNN7rZw@kili/
>
> I did a quick check but didn't don't see the LKP report...
>

Yes, LKP dropped all the cc when reported, even I saw after merging the
changes. I think this is the one:

https://lore.kernel.org/all/202301052307.JYt1GWaJ-lkp@intel.com/

> Also a Fixes: tag too, no?
>

+1, if you split make sure you tag fixes to the right one(mainly one
that changes return from acpi_get_cache_info())

> Thanks,
> Conor.



-- 
Regards,
Sudeep