linux-kernel - Re: [PATCH v2] arch/cacheflush: Introduce flush_all

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Date:   Sat, 20 Aug 2022 08:10:48 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     Ira Weiny <ira.weiny@...el.com>
Cc:     linux-arch@...r.kernel.org, dan.j.williams@...el.com,
        peterz@...radead.org, mark.rutland@....com, dave.jiang@...el.com,
        Jonathan.Cameron@...wei.com, a.manzanares@...sung.com,
        bwidawsk@...nel.org, alison.schofield@...el.com,
        linux-cxl@...r.kernel.org, nvdimm@...ts.linux.dev, x86@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] arch/cacheflush: Introduce flush_all_caches()

On Fri, 19 Aug 2022, Ira Weiny wrote:

>Did you mean "must"?

Yep.

>> + * such as those which caches are in a consistent state. The
>> + * caller can verify the situation early on.
>> + */
>> +#ifndef flush_all_caches
>> +# define flush_all_caches_capable() false
>> +static inline void flush_all_caches(void)
>> +{
>> +	WARN_ON_ONCE("cache invalidation required\n");
>> +}
>
>With the addition of flush_all_caches_capable() will flush_all_caches() ever be
>called?

No, it should not. Hence you get a splat if you call it bogusly.