linux-kernel - Re: [PATCH V3 13/15] parisc/kmap: Remove duplicate kmap code

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Message-ID: <20200507225039.GA1428632@iweiny-DESK2.sc.intel.com>
Date:   Thu, 7 May 2020 15:50:40 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        "David S. Miller" <davem@...emloft.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Chris Zankel <chris@...kel.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        Dan Williams <dan.j.williams@...el.com>,
        linux-snps-arc@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-csky@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, sparclinux@...r.kernel.org,
        linux-xtensa@...ux-xtensa.org, dri-devel@...ts.freedesktop.org,
        Christian Koenig <christian.koenig@....com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH V3 13/15] parisc/kmap: Remove duplicate kmap code

On Thu, May 07, 2020 at 01:52:58PM -0700, Andrew Morton wrote:
> On Thu,  7 May 2020 08:00:01 -0700 ira.weiny@...el.com wrote:
> 
> > parisc reimplements the kmap calls except to flush it's dcache.  This is
> > arguably an abuse of kmap but regardless it is messy and confusing.
> > 
> > Remove the duplicate code and have parisc define
> > ARCH_HAS_FLUSH_ON_KUNMAP for a kunmap_flush_on_unmap() architecture
> > specific call to flush the cache.
> 
> checkpatch says:
> 
> ERROR: #define of 'ARCH_HAS_FLUSH_ON_KUNMAP' is wrong - use Kconfig variables or standard guards instead
> #69: FILE: arch/parisc/include/asm/cacheflush.h:103:
> +#define ARCH_HAS_FLUSH_ON_KUNMAP
> 
> which is fair enough, I guess.  More conventional would be
> 
> arch/parisc/include/asm/cacheflush.h:
> 
> static inline void kunmap_flush_on_unmap(void *addr)
> {
> 	...
> }
> #define kunmap_flush_on_unmap kunmap_flush_on_unmap
> 
> 
> include/linux/highmem.h:
> 
> #ifndef kunmap_flush_on_unmap
> static inline void kunmap_flush_on_unmap(void *addr)
> {
> }
> #define kunmap_flush_on_unmap kunmap_flush_on_unmap
> #endif
> 
> 
> static inline void kunmap_atomic_high(void *addr)
> {
> 	/* Mostly nothing to do in the CONFIG_HIGHMEM=n case as kunmap_atomic()
> 	 * handles re-enabling faults + preemption */
> 	kunmap_flush_on_unmap(addr);
> }
> 
> 
> but I don't really think it's worth bothering changing it.	
> 
> (Ditto patch 3/15)

Yes I was following the pattern already there.

I'll fix up the last patch now.
Ira