Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 22 Aug 2022 06:37:36 -0700
From:   Davidlohr Bueso <dave@stgolabs.net>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     linux-arch@vger.kernel.org, dan.j.williams@intel.com,
        peterz@infradead.org, mark.rutland@arm.com, dave.jiang@intel.com,
        Jonathan.Cameron@huawei.com, a.manzanares@samsung.com,
        bwidawsk@kernel.org, alison.schofield@intel.com,
        ira.weiny@intel.com, linux-cxl@vger.kernel.org,
        nvdimm@lists.linux.dev, x86@kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] arch/cacheflush: Introduce flush_all_caches()
Message-ID: <20220822133736.roxmpj6sfo6gsij2@offworld>
References: <20220819171024.1766857-1-dave@stgolabs.net>
 <YwMkUMiKf3ZyMDDF@infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Disposition: inline
In-Reply-To: <YwMkUMiKf3ZyMDDF@infradead.org>
User-Agent: NeoMutt/20220429
Precedence: bulk

On Sun, 21 Aug 2022, Christoph Hellwig wrote:

>On Fri, Aug 19, 2022 at 10:10:24AM -0700, Davidlohr Bueso wrote:
>> index b192d917a6d0..ac4d4fd4e508 100644
>> --- a/arch/x86/include/asm/cacheflush.h
>> +++ b/arch/x86/include/asm/cacheflush.h
>> @@ -10,4 +10,8 @@
>>
>>  void clflush_cache_range(void *addr, unsigned int size);
>>
>> +/* see comments in the stub version */
>> +#define flush_all_caches() \
>> +	do { wbinvd_on_all_cpus(); } while(0)
>
>Yikes.  This is just a horrible, horrible name and placement for a bad
>hack that should have no generic relevance.

Why does this have no generic relevance? There's already been discussions
on how much wbinv is hated[0].

>Please fix up the naming to make it clear that this function is for a
>very specific nvdimm use case, and move it to a nvdimm-specific header
>file.

Do you have any suggestions for a name? And, as the changelog describes,
this is not nvdimm specific anymore, and the whole point of all this is
volatile memory components for cxl, hence nvdimm namespace is bogus.

[0] https://lore.kernel.org/all/Yvtc2u1J%2Fqip8za9@worktop.programming.kicks-ass.net/

Thanks,
Davidlohr