Re: [PATCH 1/2] Massive code cleanup of sys_msync()

Peter Zijlstra
2008-01-15T19:29:24Z

On Tue, 2008-01-15 at 22:26 +0300, Anton Salikhmetov wrote:
> 2008/1/15, Randy Dunlap <randy.dunlap@oracle.com>:
> > On Tue, 15 Jan 2008 22:02:54 +0300 Anton Salikhmetov wrote:
> >
> > > 2008/1/15, Christoph Hellwig <hch@infradead.org>:
> > > > On Tue, Jan 15, 2008 at 07:02:44PM +0300, Anton Salikhmetov wrote:
> >
> > > > > @@ -33,71 +34,65 @@ asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
> > > > > unsigned long end;
> > > > > struct mm_struct *mm = current->mm;
> > > > > struct vm_area_struct *vma;
> > > > > - int unmapped_error = 0;
> > > > > - int error = -EINVAL;
> > > > > + int error = 0, unmapped_error = 0;
> > > > >
> > > > > if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
> > > > > - goto out;
> > > > > + return -EINVAL;
> > > > > if (start & ~PAGE_MASK)
> > > > > - goto out;
> > > > > + return -EINVAL;
> > > >
> > > > The goto out for a simple return style is used quite commonly in kernel
> > > > code to have a single return statement which makes code maintaince, e.g.
> > > > adding locks or allocations simpler. Not sure that getting rid of it
> > > > makes a lot of sense.
> > >
> > > Sorry, I can't agree. That's what is written in the CodingStyle document:
> > >
> > > The goto statement comes in handy when a function exits from multiple
> > > locations and some common work such as cleanup has to be done.
> >
> > CodingStyle does not try to cover Everything. Nor do we want it to.
> >
> > At any rate, there is a desire for functions to have a single point
> > of return, regardless of the amount of cleanup to be done, so I agree
> > with Christoph's comments.
>
> Should I replace "return -EINVAL;" statement with the following?
>
> {
> error = -EINVAL;
> goto out;
> }

Notice that error is already -EINVAL, so a simple goto should suffice.