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

[christophe leroy]

Le 08/10/2015 21:12, Scott Wood a Ãcrit :
> On Wed, 2015-10-07 at 14:49 +0200, Christophe Leroy wrote:
> > Le 29/09/2015 02:29, Scott Wood a Ãcrit :
> > > 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 ?
> start and stop are already unsigned long.
>
> > 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.
> Why would size be signed?

Oops, indeed I misunderstood your comment, thought you said:
* size has to be signed int instead of unsigned int
* addresses have to be void *

I understand now that size and addresses should be unsigned long instead

Christophe


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