[Cbe-oss-dev] [PATCH 4/6] spufs: extension of spu_create to support affinity definition

[Arnd Bergmann]

On Monday 12 February 2007 21:07, Benjamin Herrenschmidt wrote:
> 
> > >  {
> > >     int ret;
> > > +   struct spu_gang *gang = NULL;
> > > +   struct spu_context *neighbor = NULL;
> > >  
> > >     ret = -EPERM;
> > >     if ((flags & SPU_CREATE_NOSCHED) &&
> > 
> > style: don't initialize local variables in their definition.
> 
> Why ? I do that all the time 

gcc won't be able to warn about uninitialized use if you do it.
There are exceptions, e.g. when a variable is basically the object
pointer, as in

int callback(void *data)
{
	struct foo *foo = data;
	...
}

I do it as well.

But especially variables initialized to NULL or 0 smell wrong.

If you have

int foo(void)
{
	int bar = 0;
	int ret;

	ret = something();
	/*
	 * lots of code here ...
	 */
	if (!ret)
		bar = get_bar();

	return bar;
}

it can easily happen that you add a user of bar before the
initialization, therefore better write it as

int foo(void)
{
	int bar;
	int ret;

	ret = something();
	/*
	 * lots of code here ...
	 */
	bar = 0;
	if (!ret)
		bar = get_bar();

	return bar;
}

or

int foo(void)
{
	int bar;
	int ret;

	ret = something();
	/*
	 * lots of code here ...
	 */
	if (!ret)
		bar = get_bar();
	else
		bar = 0;

	return bar;
}

	Arnd <><