On Wed, 2010-10-06 at 10:22 -0400, Nicolas Pitre wrote:
> On Wed, 6 Oct 2010, Daniel Walker wrote:
>
> > On Tue, 2010-10-05 at 22:55 -0400, Nicolas Pitre wrote:
> > > On Tue, 5 Oct 2010, Daniel Walker wrote:
> > >
> > > > +#if !defined(CONFIG_CPU_V7)
> > > > +static inline char
> > > > +__dcc_getchar(void)
> > > > +{
> > > > + char __c;
> > > > +
> > > > + asm("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg"
> > > > + : "=r" (__c) : : "cc");
> > > > +
> > > > + return __c;
> > > > +}
> > > > +#else
> > > > +static inline char
> > > > +__dcc_getchar(void)
> > > > +{
> > > > + char __c;
> > > > +
> > > > + asm(
> > > > + "get_wait: mrc p14, 0, pc, c0, c1, 0 \n\
> > > > + bne get_wait
> > > > \n\
> > > > + mrc p14, 0, %0, c0, c5, 0 @ read comms
> > > > data reg"
> > > > + : "=r" (__c) : : "cc");
> > > > +
> > > > + return __c;
> > > > +}
> > > > +#endif
> > > > +
> > > > +#if !defined(CONFIG_CPU_V7)
> > > > +static inline void
> > > > +__dcc_putchar(char c)
> > > > +{
> > > > + asm("mcr p14, 0, %0, c0, c5, 0 @ write a char"
> > > > + : /* no output register */
> > > > + : "r" (c) : "cc");
> > > > +}
> > > > +#else
> > > > +static inline void
> > > > +__dcc_putchar(char c)
> > > > +{
> > > > + asm(
> > > > + "put_wait: mrc p14, 0, pc, c0, c1, 0 \n\
> > > > + bcs put_wait \n\
> > > > + mcr p14, 0, %0, c0, c5, 0 "
> > > > + : : "r" (c) : "cc");
> > > > +}
> > > > +#endif
> > >
> > > Please move the #ifdef conditionals inside the respective functions so
> > > to have only one function pair with the various alternatives embedded
> > > into them.
> >
> > My typical clean up policy is do to the inverse of what your suggesting.
> > Mainly because that's the method that I see used extensive in generic
> > parts of the kernel.
>
> Do you have an example? I don't see such thing in generic code, unless
> two versions of the same function are totally different. In this case
> you have only the inner inline asm code that is different.
These may not be the best examples but in include/linux/workqueue.h line
150, work_static() for instance if fully inside an ifdef. There is one
other function example in that file, an one macro version. Also some in
include/linux/ftrace.h , but in that case either the functions do
something or nothing. ftrace.h is a little bit confsued, it has example
of it your way and my way.
It doesn't appear to be a constant .. I see it your way and my way.
> > From my perspective there are pluses an minuses to both. Your method
> > reduces lines, and duplication. My method makes the code easier to read.
>
> I disagree. In reviewing your patch I had to go back and forth between
> the different versions just to figure out what was actually different to
> justify this #ifdef in the first place. If the #ifdef..#endif was
> surrounding only the different inline asm statements then the difference
> would have been more obvious.
You would have had to go back and forth either way , wouldn't you? In
this case the functions are actually totally different.
Daniel
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