Re: [PATCH(s)][RFC] variable size and signedness issues in ldt.c -potential problem?

[Jesper Juhl]

On Mon, 12 Jan 2004, Andrew Morton wrote:

> Jesper Juhl <juhl-lkml@xxxxxx> wrote:
> >
> >
> > >
> > > -static int read_ldt(void __user * ptr, unsigned long bytecount)
> > > +static int read_ldt(void __user *ptr, unsigned long bytecount)
> > >  {
> > >  	int err, i;
> > >  	unsigned long size;
> > > +	unsigned long bytes;
> > >  	struct mm_struct * mm = current->mm;
> > >
> > >  	if (!mm->context.size)
> > > @@ -144,7 +145,7 @@ static int read_ldt(void __user * ptr, u
> > >  	__flush_tlb_global();
> > >
> > >  	for (i = 0; i < size; i += PAGE_SIZE) {
> > > -		int nr = i / PAGE_SIZE, bytes;
> > > +		int nr = i / PAGE_SIZE;
> > >  		char *kaddr = kmap(mm->context.ldt_pages[nr]);
> > >
> > >  		bytes = size - i;
> > >
>
> There is no additional overhead with the original code and it has the
> advantage that the scope of `bytes' covers the minimum amount of code.  I
> see no need to change this.
>
> Well.  There is a little bit of overhead of the code does:
>
> foo()
> {
> 	...
> 	{
> 		int i;
> 		...
> 	}
> 	...
> 	{
> 		int i;
> 		...
> 	}
> 	...
> }
>
> because the compiler (some versions, at least) will use eight bytes of
> stack rather than four.  But this is rarely a problem.
>

Ok, I'll let it go :-)


> > After creating the initial cleanup patch I've noticed several more
> > instances of this 'bad style'. If there's any interrest in cleaning them
> > up I'll be happy to create a patch.  Is this wanted?
>
> I'd say that this and the whitespace adjustments are far too trivial to be
> raising patches at this time.
>
You are right, it /is/ trivial - I'll leave it alone for now.  Maybe later
create a patch that does a more thorough cleanup and send it to the
trivial patch monkey.


-- Jesper Juhl

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