Re: [PATCH 1/3] cacheinfo: Check sib_leaf in cache_leaves_are_shared()

From: Conor Dooley <conor.dooley@microchip.com>
To: Pierre Gondois <pierre.gondois@arm.com>
Cc: <linux-kernel@vger.kernel.org>, Radu Rendec <rrendec@redhat.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Akihiko Odaki <akihiko.odaki@daynix.com>,
	Palmer Dabbelt <palmer@rivosinc.com>,
	Gavin Shan <gshan@redhat.com>,
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/3] cacheinfo: Check sib_leaf in cache_leaves_are_shared()
Date: Mon, 27 Mar 2023 15:04:15 +0100	[thread overview]
Message-ID: <267f5e37-2cfd-4833-a74c-bfc56fe3671c@spud> (raw)
In-Reply-To: <20230327115953.788244-2-pierre.gondois@arm.com>

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On Mon, Mar 27, 2023 at 01:59:49PM +0200, Pierre Gondois wrote:
> If 'this_leaf' is a L2 cache (or higher) and 'sib_leaf' is a L1 cache,
> the caches are detected as shared.
> Indeed, cache_leaves_are_shared() only checks the cache level of
> 'this_leaf' when 'sib_leaf''s cache level should also be checked.

nit: this commit message reads quite weirdly as there's a missing "do
foo" statement, followed by "also do bar".

> 
> Also update the comment: the function is called when populating
> 'shared_cpu_map'.
> 
> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
> ---
>  drivers/base/cacheinfo.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
> index f6573c335f4c..4ca117574af1 100644
> --- a/drivers/base/cacheinfo.c
> +++ b/drivers/base/cacheinfo.c
> @@ -38,11 +38,10 @@ static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf,
>  {
>  	/*
>  	 * For non DT/ACPI systems, assume unique level 1 caches,
> -	 * system-wide shared caches for all other levels. This will be used
> -	 * only if arch specific code has not populated shared_cpu_map
> +	 * system-wide shared caches for all other levels.
>  	 */
>  	if (!(IS_ENABLED(CONFIG_OF) || IS_ENABLED(CONFIG_ACPI)))
> -		return !(this_leaf->level == 1);
> +		return (this_leaf->level != 1) || (sib_leaf->level != 1);

So this is
Fixes: f16d1becf96f ("cacheinfo: Use cache identifiers to check if the caches are shared if available")
then?

Cheers,
Conor.

>  
>  	if ((sib_leaf->attributes & CACHE_ID) &&
>  	    (this_leaf->attributes & CACHE_ID))
> -- 
> 2.25.1
> 
> 

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