Re: [PATCH v2 22/25] powerpc32: move xxxxx_dcache_range() functions inline

[Christophe Leroy]

Le 29/09/2015 02:29, Scott Wood a écrit :
> On Tue, Sep 22, 2015 at 06:51:13PM +0200, Christophe Leroy wrote:
> > flush/clean/invalidate _dcache_range() functions are all very
> > similar and are quite short. They are mainly used in __dma_sync()
> > perf_event locate them in the top 3 consumming functions during
> > heavy ethernet activity
> >
> > They are good candidate for inlining, as __dma_sync() does
> > almost nothing but calling them
> >
> > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> > ---
> > New in v2
> >
> >   arch/powerpc/include/asm/cacheflush.h | 55 +++++++++++++++++++++++++++--
> >   arch/powerpc/kernel/misc_32.S         | 65 -----------------------------------
> >   arch/powerpc/kernel/ppc_ksyms.c       |  2 ++
> >   3 files changed, 54 insertions(+), 68 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/cacheflush.h b/arch/powerpc/include/asm/cacheflush.h
> > index 6229e6b..6169604 100644
> > --- a/arch/powerpc/include/asm/cacheflush.h
> > +++ b/arch/powerpc/include/asm/cacheflush.h
> > @@ -47,12 +47,61 @@ static inline void __flush_dcache_icache_phys(unsigned long physaddr)
> >   }
> >   #endif
> >   
> > -extern void flush_dcache_range(unsigned long start, unsigned long stop);
> >   #ifdef CONFIG_PPC32
> > -extern void clean_dcache_range(unsigned long start, unsigned long stop);
> > -extern void invalidate_dcache_range(unsigned long start, unsigned long stop);
> > +/*
> > + * Write any modified data cache blocks out to memory and invalidate them.
> > + * Does not invalidate the corresponding instruction cache blocks.
> > + */
> > +static inline void flush_dcache_range(unsigned long start, unsigned long stop)
> > +{
> > +	void *addr = (void *)(start & ~(L1_CACHE_BYTES - 1));
> > +	unsigned int size = stop - (unsigned long)addr + (L1_CACHE_BYTES - 1);
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < size >> L1_CACHE_SHIFT; i++, addr += L1_CACHE_BYTES)
> > +		dcbf(addr);
> > +	if (i)
> > +		mb();	/* sync */
> > +}
> I know this is 32-bit-specific code, but it's still bad practice to use
> "unsigned int" for addresses or sizes thereof.
Ok, I can fix size, but what about start and stop ? If I change that, it 
means I also have to fix all caller. Do you expect me to do that ?

And it is very unlykely, but what if for some reason someone wants to 
invalidate the entire user address space which is 3Gbytes size ? A 
signed size would be negative here.

Christophe
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